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In This Post we are  providing  CHAPTER 8 WEATHER INSTRUMENT, MAP AND CHARTS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON WEATHER INSTRUMENT, MAP AND CHARTS

Question 1.
How is weather forecasting useful for different groups?
Answer:
Weather forecasting is very important for all groups:

• Weather forecasts help in taking safety measures in advance in case of the likelihood of bad weather.
• It reduces the likely loss from natural calamities. Had tsunami been predicted in advance, the loss that happened could be minimized to a great extent.
• Predicting weather a few days in advance may prove very useful to farmers and to the crew of ships, pilots, fishermen, defence personnel, etc.

Question 2.
Explain in short about Wind Vane.
Answer:
Purpose: Wind vane is a device used to measure the direction of the wind. Structure: The wind vane is a light-weight revolving plate with an arrowhead on one end and two metal plates attached to the other end at the same angle. This revolving plate is mounted on a rod in such a manner that it is free to rotate on a horizontal plane. It responds even to a slight blow of wind.
Important Aspect: The arrow always points towards the direction from which the wind blows.

Question 3.
Explain in short about Anemometer.
Answer:

An anemometer is an instrument that measures wind speed and wind pressure. Anemometers are important tools for meteorologists, who study weather patterns. They are also important to the work of physicists, who study the way air moves. The most common type of anemometer has three or four cups attached to horizontal arms. The arms are attached to a vertical rod. As the wind blows, the cups rotate, making the rod spin. The stronger the wind blows, the faster the rod spins. The anemometer counts the number of rotations, or turns, which is used to calculate wind speed. Because wind speeds are not consistent—there are gusts and lulls-wind speed is usually averaged over a short period of time.

A similar type of anemometer counts the revolutions made by windmill-style blades. The rod of windmill anemometers rotates horizontally. Other anemometers calculate wind speed in different ways. A hot-wire anemometer takes advantage of the fact that air cools a heated object when it flows over it.

Question 4.
How do Weather observatories work in India?
Answer:
Each day weather maps are prepared for that day by the Meteorological Department from the data obtained from observations made at various weather stations across the world. In India, weather-related information is collected and published under the auspices of the Indian Meteorological Department, New Delhi, which is also responsible for weather forecasting.

The Indian Meteorological Department (IMD) was established in 1875, with its headquarters at Calcutta. The IMD headquarters are presently located at New Delhi.

Question 5.
Write a short note on Stevenson Screen.
Answer:
The Stevenson screen is designed to protect thermometers from precipitation and direct sunlight while allowing air to circulate freely around them. Formation: It is made from wood with louvered sides to allow free and even flow of air. It is painted white to reflect radiation. It stands on four legs and is about 3 feet 6 inches above the level of the ground. The legs must be sufficiently rigid and be buried sufficiently in the ground to prevent shaking.

The front panel is hinged at the bottom to form a door, which allows for maintenance and reading of the thermometers. The door of Stevenson screen is always towards the north in the northern hemisphere and towards the south in the southern hemisphere because direct sunrays also affect mercury.

Objective: The purpose of the Stevenson screen is to create a uniform temperature enclosure that closely represents the same temperature as the air outside.

Question 6.
What is aneroid barometer? How does it work?
Answer:
Aneroid barometer gets its name from the Greek word, aneros in which ‘a’ means ‘not’, ‘neros’ means ‘moisture’, hence aneroid means without liquid. It is a compact and portable instrument. It consists of a corrugated metal box made up of a thin alloy, sealed completely and made airtight after partial exhaustion of air.

It has a thin flexible lid, which is sensitive to changes of pressure. As the pressure increases, the lid is pressed inward, and this, in turn, moves a system of levers connected to a pointer, which moves clockwise over the graduated dial and gives higher reading. When the pressure decreases, the lid is pushed outward and the pointer moves counter clockwise, indicating lower pressure. Barograph works on the principle of aneroid barometer.

There are a number of vacuum boxes placed one above the other so that the displacement is large. A system of levers magnifies this movement which is recorded by a pen on a paper attached to a rotating drum. The readings of a barograph are not always accurate, and therefore, they are standardised by comparing them with a mercury barometer reading.

Question 7.
Differentiate between:

(i) Wet bulb and dry bulb,
Answer:
The dry bulb and wet bulb thermometers are two identical thermometers fixed to a wooden frame. But they are different in following way:

Dry Bulb Thermometer	Wet Bulb Thermometer
It is used to measure lowest humidity	It is used to measure highest humidity.
The bulb of the dry bulb thermometer is kept uncovered and is exposed to the air	The bulb of the wet bulb thermometer is wrapped up with a piece of wet muslin, which is kept continuously moist by dipping a strand of it into a small vessel of distilled water.
Its temperature remains high.	The evaporation from the wet bulb lowers its temperature.

(ii) Aneroid Barometer and Mercury Barometer.
Answer:

Aneroid Barometer	Mercury Barometer
Aneroid barometer gets its name from the Greek word, aneros in which ‘a’ means ‘not’, ‘neros’ means ‘moisture’, hence aneroid means without liquid. It is a compact and portable instrument.	Mercury barometer is an accurate instrument and is used as a standard. In it the atmospheric pressure of any place is balanced against the weight of a column of mercury in an inverted glass tube.
It is filled with alcohol	It is filled with mercury
It is used to measure lowest temperature.	It is used to measure highest temperature.

(iii) Centigrade and the Fahrenheit.
Answer:
Both are units of measuring temperature but they have some differences.

Centigrade	Fahrenheit
On the Centigrade thermometer, the temperature of melting ice is marked 0°C and that of boiling water as 100°C, and the interval between the two is divided into 100 equal parts.	On the Fahrenheit thermometer, the freezing and boiling points of water are graduated as 32°F and 212°F respectively.
Centigrade = (Fahrenheit -32)	Fahrenheit= Centigrade ×\frac { 9 }{ 5 } +32

Question 6.
How is information about weather and related facts collected organized and dispensed in India?
Answer:

In India, weather-related information is collected and published under the auspices of the Indian Meteorological Department, New Delhi, which is also responsible for weather forecasting.

A typical surface observatory has instruments for measuring and recording weather elements like temperature (maximum and minimum), air pressure, humidity, clouds, wind and rainfall. Specialised observatories also record elements like radiation, ozone atmospheric trace gases, pollution and atmospheric electricity. These observations are taken all over the globe at fixed times of the day as decided by the WMO and the use of instruments are made conforming to international standards, thus making observations globally compatible. In India, meteorological observations are normally classified into five categories depending upon their instruments and the number of daily observations taken. The highest category is Class-I.

Typical instrumental facility available in a Class-I observatory consists of the following:

• Maximum and minimum thermometers
• Anemometer and wind vane
• Dry and Wet bulb thermometer
• Rain gauge
• Barometer

Observations are taken in these observatories normally at 00,03,06,09, 12,15,18,21 hours (Greenwich Mean Time) around the globe. However, for logistic reasons, some of the observatories take limited number of daily observations upper air observation during daytime only.

Weather satellites make comprehensive and large-scale observations of different meteorological elements at the ground level as well in the upper layers of the atmosphere. The geo-stationary satellites provide space-based observations about weather conditions. The Indian National Satellite (INSAT) provides valuable observations of temperature, cloud cover, wind and associated weather phenomena.

Question 7.
Explain the working of a barometer.
Answer:
The instrument used to measure atmospheric pressure is called a barometer. The unit of measurement is in the millibar. The most commonly used barometers are the mercury barometer, aneroid barometer and barographs. All the three work differently. Their working is explained below briefly:

1. Mercury barometer: It is an accurate instrument and is used as a standard. In it the atmospheric pressure of any place is balanced against the weight of a column of mercury in an inverted glass tube.

2.Aneroid barometer: It is a compact and portable instrument. It consists of a corrugated metal box made up of a thin alloy, sealed completely and made airtight after partial exhaustion of air. It has a thin flexible lid, which is sensitive to changes of pressure. As the pressure increases, the lid is pressed inward, and this, in turn, moves a system of levers connected to a pointer, which moves clockwise over the graduated dial and gives higher reading. When the pressure decreases, the lid is pushed outward and the pointer moves counter clockwise, indicating lower pressure.

3. Barograph: It works on the principle of aneroid barometer. There are a number of vacuum boxes placed one above the other so that the displacement is large. A system of levers magnifies this movement which is recorded by a pen on a paper attached to a rotating drum. The readings of a barograph are not
always accurate, and therefore, they are standardised by comparing them with a mercury barometer reading.

Question 8.
Write short notes on the following:
(i) Safe place for a thermometer
(ii) Indian Daily Weather report
Answer:
(i) Safe place for thermometer: It is not safe to keep a thermometer in sunlight. We should also not keep it in airtight surroundings. The Stevenson screen is designed to protect thermometers from precipitation and direct sunlight while allowing air to circulate freely around them. It is made from wood with louvered sides to allow free and even flow of air. It is painted white to reflect radiation. The purpose of the Stevenson screen is to create a uniform temperature enclosure that closely represents the same temperature as the air outside.

It stands on four legs and is about 3 feet 6 inches above the level of the ground. The legs must be sufficiently rigid and be buried sufficiently in the ground to prevent shaking. The front panel is hinged at the bottom to form a door, which allows for maintenance and reading of the thermometers. The door of Stevenson screen is always towards the north in the northern hemisphere and towards the south in the southern hemisphere because direct sunrays also affect mercury.

(ii) Indian Daily Weather Report: IMD became a member of the World Meteorological Organization after independence on 27 April 1949. The agency has gained in prominence due to the significance of the monsoon rains on Indian agriculture. It plays a vital role in preparing the annual monsoon forecast, as well as in tracking the progress of the monsoon across India every season.

IMD undertakes observations, communications, forecasting and weather services. In collaboration with the Indian Space Research Organisation, the IMD also uses the IRS series and the Indian National Satellite System (INSAT) for weather monitoring of the Indian subcontinent. IMD was the first weather bureau of a developing country to develop and maintain its own satellite system. IMD is one of the 6 worldwide Regional Specialized Meteorological Centers of the Tropical Cyclone Programme of the World Weather Watch of the World Meteorological Organization. It is regional nodal agency for forecasting, naming and disseminating warnings about tropical cyclone in the Indian Ocean north of the Equator.

Question 9.
Explain the history of weather forecasting in India.
Answer:
In 1686, Edmond Halley published his treatise on the Indian summer monsoon, which he attributed to a seasonal reversal of winds due to the differential heating of the Asian land mass and the Indian Ocean. The first meteorological observatories were established in India by the British East India Company. These included the Calcutta Observatory in 1785, the Madras Observatory in 1796 and the Colaba Observatory in 1826. Several other observatories were established in India during the first half of the 19th century by various provincial governments.

After a tropical cyclone hit Calcutta in 1864, and the subsequent famines in 1866 and 1871 due to the failure of the monsoons, it was decided to organise the collection and analysis of meteorological observations under one roof.
As a result, the Indian Meteorology Department was established in 1875. Henry Francis Blanford was appointed the first Meteorological Reporter of the IMD. In May 1889,Sir John Eliot was appointed the first Director General of Observatories in the erstwhile capital, Calcutta. The IMD headquarters were later shifted to Shimla in 1905, then to Pune in 1928 and finally to New Delhi in 1944.

Question 10.
Explain the instruments used to measure atmospheric pressure.
Answer:
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. A simple barometer consists of a long glass tube (closed at one end, open at the other) filled with mercury and turned upside down into a container of mercury. The barometer works by balancing the mercury in the glass tube against the outside air pressure, just like a set of scales. As air pressure increases—that is, as the air becomes heavier—it pushes more of the mercury up into the tube. As air pressure decreases, more of the mercury drains from the tube. So the level of mercury in the tube provides a precise measure of air pressure.

Mercury barometer is . an accurate instrument and is used as a standard. In it the atmospheric pressure of any place is balanced against the weight of a column of mercury in an inverted glass tube. Aneroid barometer is a compact and portable instrument. It consists of a corrugated metal box made up of a thin alloy, sealed completely and made airtight after partial exhaustion of air. It has a thin flexible lid, which is sensitive to changes of pressure. As the pressure increases, the lid is pressed inward, and this, in turn, moves a system of levers connected to a pointer, which moves clockwise over the graduated dial and gives higher reading.

When the pressure decreases, the lid is pushed outward and the pointer moves counterclockwise, indicating lower pressure. Barograph works on the principle of aneroid barometer. There are a number of vacuum boxes placed one above the other so that the displacement is large. A system of levers magnifies this movement which is recorded by a pen on a paper attached to a rotating drum. The readings of a barograph are not always accurate, and therefore, they are standardised by comparing them with a mercury barometer reading.

In This Post we are  providing  CHAPTER 6 INTRODUCTION TO AERIAL PHOTOGRAPHS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON INTRODUCTION TO AERIAL PHOTOGRAPHS

Question 1.
Compute the scale of an aerial photograph when the flying height of the aircraft is 7500 m and the focal length of the camera is 15 cm.
Answer:
Focal Length (f) : Flying Height (H) = Photo distance (Dp) : Ground distance (Dg)
Sp = f: H
Or Sp = 15 cm : 7,500 x 100 cm
Or Sp = 1 : 750,000/15
Therefore, Sp = 1 : 50,000

Question 2.
Differentiate between:
(i) Aerial photograph and map.
(it) Aerial photographs and satellite images.
(iii) High oblique photograph and low oblique photograph.
(iv) Vertical photograph and high oblique photograph.
(v) Vertical photograph and low oblique photograph.
Answer:
(i)

Basis	Aerial Photograph	Map
Projection	It is a central Projection.	It is an orthogonal Projection.
Accuracy	An aerial photograph is geometrically incorrect. The distortion in the geometry is minimum at the centre and increases towards the edges of the photographs.	A map is geometrically correct representation of the part of the earth projected.
Scale	The scale of the photograph is not uniform.	The scale of the map is uniform throughout the map extent.
Impact of enlargement or reduction	Enlargement/reduction does not change the contents of the photographs and can easily be carried out.	Enlargement/reduction of the maps involves redrawing it afresh.
Utility	Aerial photography holds good for inaccessible and inhospitable areas.	The mapping of inaccessible and inhospitable areas is very difficult and sometimes it becomes impossible.

(ii)

Basis	Aerial Photographs	Satellite Images
Meaning	These are taken from an aeroplane or helicopter.	These are taken from man-made satellite launched in space.
Accuracy	These are less accurate as compared to satellite images.	These are more accurate as compared to aerial images.
Suitability	These are suitable for taking photographs of the earth.	These are used for taking photographs of other planets and celestial bodies.
Utility	Aerial photography holds good for inaccessible and inhospitable areas of the earth	It is useful in knowing climatic condition and weather forecast.
Disastermanagement	It is more useful in disaster management for providing relief.	It is more useful in disaster management by predicting weather and taking preventive actions.

(iii)

Basis	High Oblique Photograph	Low Oblique Photograph
Optical Axis	Deviation is more than 300 degree from the vertical axis.	Deviation is more than 30 degree from the vertical axis.
Coverage	It covers largest area.	It covers larger area.
Difference in comparison to map	It is greatest with high oblique photographs.	It is greater with low oblique photographs.
Utility	It is useful in illustrative comparison.	It is useful in recoqnaissance survey.

(iv)

Basis	Vertical Photograph	High Oblique Photograph
Optical Axis	Tilt< 3 degree i.e. exactly or nearly coincides with the vertical axis.	Deviation is more than 300 degree from the vertical axis.
Horizon	Horizon does not appear	Horizon does appear
Coverage	It covers small area.	It covers largest area.
Scale	Scale is uniform if the terrain is flat.	Scale keeps decreasing from foreground to background.
Difference in comparison to map	It is least with vertical photographs.	It is greatest with high oblique photographs.
Utility	It is useful in topographical and thematic mapping.	It is useful in illustrative comparison.

(v)

Basis	Vertical Photograph	Low Oblique Photograph
Optical Axis	Tilt< 3 degree i.e. exactly or nearly coincides with the vertical axis.	Deviation is more than 30 degree from the vertical axis.
Horizon	Horizon does not appear	Horizon does appear
Coverage	It covers small area.	It covers comparatively larger area.
Scale	Scale is uniform if the terrain is flat.	Scale keeps decreasing from foreground to background.
Difference in comparison to map	It is least with vertical photographs.	It is relatively greater with low oblique photographs.
Utility	It is useful in topographical and thematic mapping.	It is useful in reconnaissance survey.

Question 3.
Explain about different types of aerial photographs on the basis of position of camera axis.
Answer:
Types of Aerial Photographs Based on
the Position of the Cameral Axis:
1. Vertical Photographs: While taking aerial photographs, two distinct axes are formed from the camera lens centre, one towards the ground plane and the other towards the photo plane. The perpendicular dropped from the camera lens centre to the ground plane is termed as the vertical axis, whereas the plumb line drawn from the lens centre to the photo plane is known as the photographic/optical axis. When the photo plane is kept parallel to the ground plane, the two axes also coincide with each other. The photograph so obtained is known as vertical aerial photograph

2. Low Oblique: An aerial photograph
taken with an intentional deviation of 15° to 30° in the camera axis from the vertical axis is referred to as the low oblique photograph. This kind of photograph is often used in reconnaissance surveys. It is shown with the help of following figure.

3. High Oblique: The high oblique are photographs obtained when the camera axis is intentionally inclined about 60° from the vertical axis. Such photography is useful in illustrative surveys. It is shown with the help of following figure.

Question 4.
How can we classify aerial photographs on the basis of scale?
Answer:
There are three types of Aerial Photographs Based on Scale.

1. Large Scale Photographs: When the scale of an aerial photograph is 1:15,000 and larger, the photography is classified as large-scale photograph. It is shown with the help of following figure.
   
2. Medium Scale Photographs: The aerial photographs with a scale ranging between 1 : 15,000 and 1 : 30,000 are usually treated as medium scale photographs as shown in the figure given below:
   
3. Small Scale Photographs: The
   photographs with the scale being smaller than 1 : 30,000, are referred to as small scale photographs as shown in the figure.
   

Question 5.
Explain in detail about aerial photographs and satellite images.
Answer:
These days, it has become very easy to draw’ maps and interpret them through aerial photographs and satellite images. It requires a special type of training to understand and interpret aerial photographs. Many countries are making use of aerial photographs not only for defence purposes but also for planning land use, development of cities and towns, development of multipurpose projects etc.

Satellite images are used to predict climatic conditions. It becomes easy to predict weather by using satellite images, wre can find mineral availability, land use plan by making use of satellite images.

Question 6.
Explain different types of projection.
Answer:
There are three types of projection:
1. Parallel Projection: In this projection, the projecting rays are parallel but not necessarily perpendicular. The triangle ABC is projected on LL1 as triangle abc.

2. Orthogonal Projection: This is a special case of parallel projections. Maps are orthogonal projections of the ground. The advantage of this projection is that the distances, angles or areas on the plane are independent of the elevation differences of the objects. In the figure given below an orthogonal projection is where the projecting rays are perpendicular to the line LL1

3. Central Projection: Figure given below shows an example of Central Projection. In this figure the projecting rays Aa, Bb and Cc pass through a common point O, which is called the perspective Centre. The image projected by a lens is treated like a central projection. An aerial photograph, as discussed earlier is a central projection. In an absolutely vertical flat terrain the aerial photograph will be geometrically the same as the corresponding map of the area. However, because of the tilt of the photograph and relief variations of the ground photographed, an aerial photograph differs geometrically from the map of the corresponding area.

Class 11 Practical Work in Geography Chapter 6 Viva Questions

Question 7.
Name three agencies eligible to take aerial photographs in India.
Answer:
In India three flying agencies are officially permitted to carry out aerial photography. They are:

1. Indian Air Force,
2. Air Survey Company, Kolkata and
3. National Remote Sensing Agency, Hyderabad.

These are identified on the aerial photographs as A, B and C respectively.

Question 8.
How can aerial photograph be used to derive the photo scale formula?
Answer:
Aerial photograph may be used to derive the photo-scale formula in the following way:
Focal Length (f): Flying Height (H) = Photo distance (Dp): Ground distance (Dg).

Question 9.
How can scale of aerial photographs be obtained by establishing relationship between Photo Distance and Ground Distance?
Answer:
If additional information like ground distances of two identifiable points in an aerial photograph is available, the corresponding ground distances is expressed by Dg and for which the distances on an aerial photograph is expressed as Dp. Both are measured. In such cases, the scale of an aerial photograph will be measured as a ratio of the two, i.e. Dp/ Dg.

Question 10.
Explain how can scale of aerial photograph be measured by establishing relationship between Photo Distance and Map Distance?
Answer:
The distances between different points on the ground are not always known. However, if a reliable map is available for the area shown on an aerial photograph, it can be used to determine the photo scale. In other words, the distances between two points identifiable both on a map and the aerial photograph enable us to compute the scale of the aerial photograph (Sp).

The relationship between the two distances may be expressed as under: (Photo scale: Map scale) = (Photo distance : Map distance) We can derive Photo scale (Sp) = Photo distance (Dp): Map distance (Dm) x Map scale factor (msf).

In This Post we are  providing  CHAPTER 2 MAP SCALE NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON MAP SCALE

Question 1.
What are advantages of representative fraction?
Answer:
Representative fraction can be used in all countries whether we are acquainted with their unit system or not. Therefore, it is also called universal method of scale.

Question 2.
Explain about the importance of scale.
Answer:
A map scale provides the relationship between the map and the whole or a part of the earth’s surface shown on it. We can also express this relationship as a ratio of distances between two points on the map and the corresponding distance between the same two points on the ground.

Question 3.
What is the unit in representative fraction?
Answer:
There is no unit in representative fraction. It is only the ratio of distance on map and distance on ground.

Question 4.
What is the utility of scale in a map?
Answer:
A map scale provides the relationship between the map and the whole or a part of the earth’s surface shown on it. We can also express this relationship as a ratio of distances between two points on the map and the corresponding distance between the same two points on the ground.

1. Scale of a map determines whether it can reflect minor details on it. For example to locate Palam Vihar in Gurgaon if we locate it on world map, it will be of no use. It is better to use a map of Gurgaon to locate Palam Vihar on it.
2. On the basis of scale, maps are classified into small-scale maps and large-scale maps.

Question 5.
What factors must be kept in mind while selecting scale?
Answer:
We must consider following aspects while selecting scale:

• Purpose of map: If map is being drawn to study the minor details then we should make use of large scale maps and if it is to show physical features or large areas, we can use small scale maps as well. For example scale of a map of a house will be larger than map of a country.
• Space Available: Scale is also affected by availability of space for drawing maps.

Question 3.
Answer:

Basis	Representative Fraction	Graphical Scale
Meaning	It is a method of scale of a map or plan expressed as a fraction showing the ratio between a unit distance on the map or plan, and the distance measured in the same units on the ground.	It shows map distances and the corresponding ground distances using a line bar with primary and secondary divisions marked on it.
Impact	It gets affected by changing the size of maps.	It is not affected by changing the size of maps proportionally.
Unit	It has no unit.	It has a unit.

Question 6.
What are limitations of representative fraction?
Answer:
There are many limitations of representative fraction method. These are as follows:

• This method is only a fraction. It does not make use of any measurement system. Therefore it cannot be used to measure the direct distance between two places.
• Whenever maps are changed using computers, these fractions get changed.
• It is not easy to understand method for a layman.

Question 7.
In a scale statement it is mentioned that 1 inch represents four miles. Express it in representative fraction.
Answer:
1 inch on map represents 4 miles on ground.
Or 1 inch = 4 x 63360 ( 1 mile = 63360 inches)
1 inch = 2,53,440 inches.
Therefore 1 inch on map represents a distance of 2,53,440 inches on ground. In other words, 1 unit on map represents 2,53,440 units on ground.

Therefore Representative fraction

Question 8.
Convert Representative fraction 1:2,53,440 into a statement of scale (metric system).
Answer:
The given representative fraction can be converted into statement of scale in following steps:
1: 2,53,440 means that 1 unit on map represents 2,53,440 units on the ground. In other words, 1 cm will represent 2,53,440/1,00,000 km (because 1 km = 1,00,000 cm)
Therefore, 1 cm = 2.5344 km In statement of scale form we can say that 1 cm represents 2.5344 km.

Question 9.
Construct a graphical scale for representative fraction 1:50,000 in which distance is given in furlongs and miles.
Answer:
For graphical scale, to know the length of the line we need to make following calculations. 1:50,000 means 1 unit on map represents 50,000 units on ground.
In this way, 1 inch = 50,000 inches
6 inches = 50,000 x 6/63360
6 inches = 4.73 miles
Since 4.73 miles is not an integer, therefore we take 5 a
s an integer on number line. Now we need to make following calculations to present number line as 5 miles.
Since 6 inches = 4.73 miles
Therefore 5 miles = 6 x 5/4.73
5 miles will be represented by 6.34 inches.
We can make the graph by following steps:
First of all draw a 6.34 inches line and divide it in 5 important parts. Except one part from the left, let us give all parts a distance of 1.268 inch. Now divide the first part in 4 equal parts and each part will be equal to 0.32 inch.

Question 10.
Construct a graphical scale for scale 1 inch = 1 mile and which can be read in furlongs and miles.
Answer:
For graphical scale, to know the length of the line we need to make following calculations.
1 inch = 1 mile
Since 1 inch = 1 mile and therefore, 6 inches = 6 miles We can make the graph by following steps:
First of all draw a 6 inches line and divide it in 6 important parts. Except one part from the left, let us give all parts a distance of one 1 inch. Now divide the first part in 4 equal parts and each part will be equal to 0.25 inch.

In This Post we are  providing  CHAPTER 3 LATITUDE, LONGITUDE AND TIME NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON LATITUDE, LONGITUDE AND TIME

Question 1.
How can we determine latitude of a place?
Answer:
Latitude of a place may be determined with the help of the altitude of the sun or the Pole Star.

Question 2.
What is 1ST?
Answer:
The Indian Standard Time is calculated from 82°30’E meridian passing through Mirzapur. 1ST is plus 5.30 hours from the GMT ((82°30’ x 4) (330 minutes = 5 hours 30 minutes).

Question 3.
Which countries have more than one time zone?
Answer:
The countries with large east-west span may choose more than one standard meridian to get more than one time zone such as Russia, Canada and the United States of America.

Question 4.
When it is 12:00 noon in Greenwich then what will be the time at Thimbu, capital of Bhutan which is located at 90° east?
Answer:

At one degree time changes by 4 minutes Difference between Greenwich and Thimbu is equal to 90°
Therefore time difference = 90 x 4
= 360 minutes = 6 hours (360/60)

Question 5.
When it is 12:00 noon in Greenwich then what will be the time at New Orleans which is located at 90° west?
Answer:
At one degree time changes by 4 minutes Difference between Greenwich and New Orleans is equal to 90°
Therefore time difference = 90 x 4
= 360 minutes = 6 hours (360/60)
Since it is towards, west, time will decrease by 4 minutes on each longitude. Therefore, it will be 6 am in the morning.

Question 6.
When it is 12:00 noon in Greenwich then what will be the time at New York which is located at 74° west?
Answer:
At one degree time changes by 4 minutes Difference between Greenwich and New York is equal to 74°
Therefore time difference
= 74 x 4
= 296 minutes
= 4 hours 56 minutes (296/60)
Since it is towards, west, time will decrease by 4 minutes on each longitude.
Therefore, it will be 7:04 am in the morning.

Question 7.
What is International Date Line? What
is its importance?
Answer:
The world is divided into 24 time zones, there has to be a place where there is a difference in days, somewhere the day truly “starts” on the planet. The 180° line of longitude is approximately where the International Date Line passes. The time at this longitude is exactly 12 hours from the 0° longitude, irrespective of one travels westward or eastward from the Prime Meridian. Time decreases east of the Prime Meridian and increases to its west. Hence, for a person moving east of the Prime Meridian, the time would be 12 hours less than the time at 0° longitude. For another person moving westward, the time would be 12 hours more than the Prime Meridian. For example, a person moving eastward on Tuesday will count the day as Wednesday once [ the International Date Line is crossed.
Similarly, another person starting his journey on the same day, but moving westward will count the day as Monday after crossing the line.

Question 8.
Explain the relationship between r longitude and time,
Answer:
The earth rotates from west to east over its axis. It makes the sun rise in the east and set in the west. The rotation of
the earth over its axis takes 24 hours to complete one circle or 360° of longitudes. As 180° of longitudes fall both east and west of the Prime Meridian, the sun, thus takes 12 hours’ time to traverse the eastern and western hemispheres. In other words, the sun traverses 15° of longitudes per hour or one degree of longitude in every four minutes of time. The time decreases when we move from west to east and increases with our westward movement. The rate of the time at which the sun traverses over certain degrees of longitudes is used to determine the local time of an area with respect to the time at the Prime Meridian (0°Longitude). For example when it is 2 pm in Greenwich, it will be 3 pm in 15° east. (15×4 = 60 minutes = 1 hour).

Question 9.
Explain the process or drawing latitudes.
Answer:
Process of drawing latitudes:

• Draw a circle.
• Divide it into two equal halves by drawing a horizontal line in the centre. This represents the equator.
• Place a protractor on this circle in a way that 0° and 180° line on the protractor coincide with the equator on the paper.
• Now to draw 20°S, mark two points at an angle of 20° from the equator, east and west in the lower half of the circle.
• The arms of the angle cut the circle at two points. Join these two points by a line parallel to the equator. It will be 20°S.
  

Question 10.
Explain the process of drawing longitudes Ans. Process of drawing longitudes:
Answer:

• Draw a circle whose centre represents the North Pole. The circumference will represent the equator.
• Draw a vertical line through the centre of the circle, i.e. crossing the North Pole. This represents the 0° and 180° meridians, which meet at the North Pole as shown in figure given below:
  
• To draw a longitude, imagine that you are on the North Pole, i.e. at the centre of the circle as shown in Figure given above.
• Observe now that the relative directions of east and west would reverse in this case and east would be towards your left while west would be towards your right.
• Now, draw 45° E and W as shown in Figure given below:
  
• For this, place your protractor along the vertical line, coinciding with the 0° and 180° meridians and then measure 45° on both the sides, which will denote 45° . E meridian and 45° W meridian on your left and right, respectively.
• The diagram will represent the appearance of the earth if we look at it from directly above the North Pole.

In This Post we are  providing  CHAPTER 4 MAP PROJECTIONS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON MAP PROJECTIONS

Question 1.
How are conical projections drawn?
Answer:
A Conical projection is drawn by wrapping a cone round the globe and the shadow of graticule network is projected
on it. When the cone is cut open, a projection is obtained on a flat sheet. A conical projection is one, which is drawn by projecting the image of the ‘ graticule of a globe on a developable cone, which touches the globe along a parallel of latitude called the standard parallel. As the cone touches the globe located along AB, the position of this parallel on the globe coinciding with that on the cone is taken as the standard parallel. The length of other parallels on either side of this parallel are distorted.

Question 2.
What is map projection?
Answer:
It is the system of transformation of the spherical surface onto a plane | surface. It is carried out by an orderly
and systematic representation of the parallels of latitude and the meridians of longitude of the spherical earth or part of it on a plane surface on a conveniently chosen scale. In map projection we try to represent a good model of any part of the earth in its true shape and dimension. But distortion in some form or the other is inevitable.

To avoid this distortion, various methods have been devised and many types of projections are drawn. Due to this reason, map projection is also defined as the study of different methods which have been tried for transferring the lines of graticule from the globe to a flat sheet of paper.

Question 3.
What are the qualities and limitations of a globe?
Answer:
Qualities of globe can be expressed as follows:

• A globe is the best model of the earth. Due to this property of the globe, the shape and sizes of the continents and oceans are accurately shown on it.
• It shows the directions and distances very accurately.
• The globe is divided into various segments by the lines of latitude and longitude.

Limitations:

• It is expensive.
• It can neither be carried everywhere easily nor can a minor detail be shown on it.
• Besides, on the globe the meridians are semi-circles and the parallels are circles. When they are transferred on a plane surface, they become intersecting straight lines or curved lines.

Question 4.
Classify the projections on the basis of method of construction.
Answer:
On the basis of method of construction, projections are generally classified into perspective, non-perspective and conventional or mathematical.

• Perspective projections: These can be drawn taking the help of a source of light by projecting the image of a network of parallels and meridians of a globe on developable surface.
• Non-perspective projections: These are developed without the help of a source of light or casting shadow on surfaces, which can be flattened.
• Mathematical or conventional projections: These are those, which are derived by mathematical computation and formulae and have little relations with the projected image.

Question 5.
Classify projections on the basis of global properties.
Answer:
On the basis of global properties, projections are classified into:

• Equal Area Projection
• Orthomorphic Projection,
• Azimuthal Projection and
• Equidistant Projections.
  • Equal Area Projection: It is also called homolographic projection. It is that projection in which areas of various parts of the earth are represented correctly.
  • Orthomorphic or True-Shape projection: It is one in which shapes of various areas are portrayed correctly. The shape is generally maintained at the cost of the correctness of area.
  • Azimuthal or True-Bearing projection: It is one on which the direction of all points from the centre is correctly represented.
  • Equidistant or True Scale projection: It is that where the distance or scale is correctly maintained.
• However, there is no such projection, which maintains the scale correctly throughout. It can be maintained correctly only along some selected parallels and meridians as per the requirement.

Question 6.
Write a short note on developable surface and zenithal projections.
Answer:
A developable surface is one, which can be flattened, and on which, a network of latitude and longitude can be projected. A cylinder, a cone and a plane have the property of developable surface. On the basis of nature of developable surface, the projections are classified as cylindrical, conical and zenithal projections.

1. Cylindrical Projections: These are made through the use of cylindrical developable surface. A paper-made cylinder covers the globe, and the parallels and meridians are projected on it.

2. Zenithal projection: It is directly obtained on a plane surface when plane touches the globe at a point and the graticule is projected on it. Generally, the plane is so placed on the globe that it touches the globe at one of the poles. These projections are further subdivided into normal, oblique or polar as per the position of the plane touching the globe.

• Normal Projection: If the developable surface touches the globe at the equator, it is called equatorial or normal projection.
• Oblique Projection: If it is tangential to a point between the pole and the equator, it is called the oblique projection;
• Polar Projection: If it is tangential to the pole, it is called the polar projection.

Question 7.
Explain the qualities of Mercator projection.
Answer:
Mercator’s Projection is very useful for navigational purposes. A Dutch cartographer Mercator Gerardus Karmer developed this projection in 1569. The projection is based on mathematical formulae.
Properties:

• It is an orthomorphic projection in which the correct shape is maintained.
• The distance between parallels increases towards the pole.
• Like cylindrical projection, the parallels and meridians intersect each other at right angle. It has the characteristics of showing correct directions.
• A straight line joining any two points on this projection gives a constant bearing, which is called a Laxodrome or Rhumb line.
• All parallels and meridians are straight lines and they intersect each other at right angles.
• All parallels have the same length which is equal to the length of equator.
• All meridians have the same length and equal spacing. But they are longer than the corresponding meridian on the globe.
• Spacing between parallels increases towards the pole.
• Scale along the equator is correct as it is equal to the length of the equator on the globe; but other parallels are longer than the corresponding parallel on the globe; hence the scale is not correct along them.
• Shape of the area is maintained, but at the higher latitudes distortion takes place.
• The shape of small countries near the equator is truly preserved while it increases towards poles.
• It is an azimuthal projection.
• This is an orthomorphic projection as scale along the meridian is equal to the scale along the parallel.

Question 6.
Explain properties, limitations and uses of cylindrical equal area projection.
Answer:
The cylindrical equal area projection is also known as the Lambert’s projection. It has been derived by projecting the surface of the globe with parallel rays on a cylinder touching it at the equator. Both the parallels and meridians are projected as straight lines intersecting one another at right angles. The pole is shown with a parallel equal to the equator; hence, the shape of the area gets highly distorted at the higher latitude.

Properties

• All parallels and meridians are straight lines intersecting each other at right angle.
• Polar parallel is also equal to the equator.
• Scale is true only along the equator.

Limitations

• Distortion increases as we move towards the pole.
• The projection is non-orthomorphic.
• Equality of area is maintained at the cost of distortion in shape.

Uses

• The projection is most suitable for the area lying between 45° N and S latitudes.
• It is suitable to show the distribution of tropical crops like rice, tea, coffee, rubber and sugarcane.

Question 7.
Explain properties of Conical Projection with one Standard Parallel.
Answer:
A conical projection is one, which is drawn by projecting the image of the graticule of a globe on a developable cone, which touches the globe along a parallel of latitude called the standard parallel. As the cone touches the globe located along AB, the position of this parallel on the globe coinciding with that on the cone is taken as the standard parallel.

Properties

• All the parallels are arcs of concentric circle and are equally spaced.
• All meridians are straight lines merging at the pole. The meridians intersect the parallels at right angles.
• The scale along all meridians is true.
• An arc of a circle represents the pole.
• The scale is true along the standard parallel but exaggerated away from the standard parallel.
• Meridians become closer to each other towards the pole.
• This projection is neither equal area nor orthomorphic.

Question 8.
Explain the limitations and uses of Conical Projection with one Standard Parallel.
Answer:
Limitations

• It is not suitable for a world map due to extreme distortions in the hemisphere opposite the one in which the standard parallel is selected.
• Even within the hemisphere, it is not suitable for representing larger areas as the distortion along the pole and near the equator is larger.

Uses

• This projection is commonly used for showing areas of mid-latitudes with limited latitudinal and larger longitudinal extent.
• A long narrow strip of land running parallel to the standard parallel and having east-west stretch is correctly shown on this projection.
• Direction along standard parallel is used to show railways, roads, narrow river valleys and international boundaries.
• This projection is suitable for showing the Canadian Pacific Railways, Trans- Siberian Railways, international boundaries between USA and Canada and the Narmada Valley.

Question 9.
Prepare graticule for a Cylindrical Equal Area Projection for the world when R.F. is 1: 300,000,000 and the interval is 15° apart.
Answer:
Construction

• Draw a circle of 2.1 cm radius;
• Mark the angles of 15°, 30°, 45°, 60°, 75° and 90° for both, northern and southern hemispheres;
• Draw a line of 13.2 cm and divide it into 24 equal parts at a distance of 0.55cm apart.
• This line represents the equator;
• Draw a line perpendicular to the equator at the point where 0° is meeting the circumference of the circle;
• Extend all the parallels equal to the length of the equator from the perpendicular line; and Complete the projection as shown in figure given below:
  

Question 10.
Draw a Mercator Projection for the world map when the R.F. is 1:250,000,000 and the interval between the latitude and longitude is 15°.
Answer:
Calculation: Radius of the reduced earth R is “1 is 1: 250,000,000 Length of the equator 2πR or

1 × 227 × 2=6.28 inches

Construction

• Draw a line of 6.28″ inches representing the equator as Equation.
• Divide it into 24 equal parts. Determine the length of each division using the following formula: Length of the equator multiplied by interval divided by 360°.
• Calculate the distance for latitude with the help of the table given below:
  Latitude Distance 15° 0.25 x 1 = 0.25″ inch 30° and so on, Complete the projection as shown in Figure given below:
  

In This Post we are  providing  CHAPTER 5 TROPGRAPHICAL MAPS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON TROPGRAPHICAL MAPS

Question 1.
What are the features of contours?
Answer:
Some basic features of contour lines are:

• A contour line is drawn to show places of equal heights.
• Contour lines and their shapes represent the height and slope or gradient of the landform.
• Space between contour lines represents slope. Closely spaced contours represent steep slopes while widely spaced contours represent gentle slope.
• When two or more contour lines merge with each other, they represent features of vertical slopes such as cliffs or waterfalls.
• Two contours of different elevation usually do not cross each other.

Question 2.
Explain how do we interpret a topographical sheet?
Answer:
It is essential to have knowledge of map language and sense of direction are essential in reading and interpreting topo-sheets. We must first look for the northline and the scale of the map and orient ourselves accordingly. We must have a thorough knowledge of the legends / key given in the map depicting various features. All topo-sheets contain a table showing conventional signs and symbols used in the map. We must be acquainted with conventional symbols, signs and colours.

Question 3.
Under which heads is a topographical sheet interpreted? Explain each in short.
Answer:
A topographic sheet is usually interpreted under the following way:

• Marginal Information: It includes the topographical sheet number, its location, grid references, its extent in degrees and minutes, scale, the districts covered, etc.
• Relief of the Area: The general topography of the area is studied to identify different landforms along with peaks, ridges, spur and the general direction of the slope.
• Drainage of the Area: We also need to interpret the important rivers and their tributaries and the type and extent of valleys formed by them, the types of drainage pattern, i.e. dendritic, radial, ring, trellis, internal, etc.
• Land Use: It includes the use of land under different categories like Natural vegetation and forest which part of the area is forested, whether it is dense forest or thin, and the categories of the forest found there like Reserved, Protected, Classified / Unclassified.
• Transport and Communication: The means of transportation include national or state highways, districts roads, cart tracks, camel tracks, footpaths, railways, waterways, major communication lines, post offices, etc. topographical sheet presents each of these.
• Settlement: Settlements are studied under rural settlements and urban settlements.
• Occupation: The general occupation of the people of the area may be identified with the help of land use and the type of settlement.

Question 4.
What factors determine the site of settlements?
Answer:
Various factors determine the site of settlements like

• Source of water
• Provision of food
• Nature of relief
• Nature and character of occupation
• Defence.

Question 5.
Write a short note on map interpretation.
Answer:
Map interpretation involves the study of factors that explain the causal relationship among several features shown on the map. For example, the distribution of natural vegetation and cultivated land can be better understood against the background of landform and drainage. Likewise, the distribution of settlements can be examined in association with the levels of transport network system and the nature of topography.

Question 6.
Explain the steps involved in drawing, a Cross-section from their contours in different topographical landforms.
Answer:
The following steps may be followed to draw cross-sections of various relief features from their contours:

• Draw a straight line cutting across the contours on the map and mark it as XY.
• Take a strip of white paper or graph and place its edge along the XY line.
• Mark the position and value of every contour that cuts the line XY.
• Choose a suitable vertical scale, e.g. V2 cm =100 metres, to draw horizontal lines parallel to each other and equal to the length of XY. The number of such lines should be equal or more than the total contour lines.
• Label the appropriate values corresponding to the contour values along the vertical of the cross-section. The numbering may be started with the lowest value represented by the contours.
• Place the edge of the marked paper along the horizontal line at the bottom line of the cross-section in such a way that XY of the paper corresponds to the XY of the map and mark the contour points.
• Draw perpendiculars from XY line, intersecting contour lines, to the corresponding line at the cross-section base.
• Smoothly join all the points marked on different lines at the cross-section base.

Question 7 .
Under which heads are topographical maps explained?
Answer:
A topographic sheet is usually interpreted in the following way:

• Marginal Information: It includes the topographical sheet number, its location, grid references, its extent in degrees and minutes, scale, the districts covered, etc.
• Relief of the Area: The general topography of the area is studied to identify different landforms along with peaks, ridges, spur and the general direction of the slope. These features are studied under the following heads:
  • Hill: With concave, convex, steep or gentle slope and shape.
  • Plateau: Whether it is broad, narrow, flat, undulating or dissected.
  • Plain: Its types, i.e. alluvial, glacial, karst, poastal, marshy, etc.
  • Mountain: General elevation, peak, passes, etc.
• Drainage of the Area: We also need to interpret the important rivers and their tributaries and the type and extent of valleys formed by them, the types of drainage pattern, i.e. dendritic, radial, ring, trellis, internal, etc.
• Land Use: It includes the use of land under different categories like Natural vegetation and forest, which part of the area is forested, whether it is dense forest or thin, and the categories of forest found there like Reserved, Protected, Classified / Unclassified.
• Transport and Communication: The means of transportation include national or state highways, district roads, cart tracks, camel tracks, footpaths, railways, waterways, major communication lines, post offices, etc. topographical sheet presents each of these.
• Settlement: Settlements are studied under the following heads:
  • Rural Settlements: The types and patterns of rural settlements, i.e. compact, semi-compact, dispersed, linear, etc.
  • Urban Settlements: Type of urban settlements and their functions, i.e. capital cities, administrative towns, religious towns, port towns, hill stations, etc.
• Occupation: The general occupation of the people of the area may be identified with the help of land use and the type of settlement. For example, in rural areas the main occupation of majority of the people is agriculture; in tribal regions, lumbering and primitive agriculture dominates and in coastal areas, fishing is practised. Similarly, in cities and towns, services and business appear to be the major occupations of the people.

Question 8.
Explain about identification of cultural features from topographical sheets
Answer:
Settlements, buildings, roads and railways are important cultural features shown on topographical sheets through conventional signs, symbols and colours. The location and pattern of distribution of different features help in understanding the area shown on the map.
Types of Settlements: Four types of rural settlements may be identified on the map:

1. Compact
2. Scattered
3. Linear
4. Circular

Urban centres are distinguished as:

• Cross-road town
• Nodal point
• Market centre
• Hill station
• Coastal resort centre
• Port
• Manufacturing centre with suburban villages or satellite towns
• Capital town
• Religious centre

Site of settlements:
It should be closely examined with reference to the contour and drainage map. Density of settlement is directly related to food supply. Sometimes, village settlements form alignments, i.e. they are spread along a river valley, road, embankment, coastline – these are called linear settlements. In the case of an urban settlement, a cross-road town assumes a fan-shaped pattern, the houses being arranged along the roadside and the crossing being at the heart of the town and the main market place. In a nodal town, the roads radiate in all directions.

Transport and Communication Pattern:
Relief, population, size and resource development pattern of an area directly influence the means of transport and communication and their density. These are depicted through conventional signs and symbols. Means of transport and communication provide useful information about the area shown on the map.

Question 9.
Name some of the methods used to depict relief features of the earth. Which of these are most common?
Answer:
A number of methods have been used to show the relief features of the Earth’s surface on maps, over the years. These methods include hachure, hill shading,’ layer tints, benchmarks and spot heights and contours. However, contours and spot heights are predominantly used to depict the relief of an area on all topographical maps.

Question 10.
Name the slope if contours show following features:

• Contours in this type of slope are widely spaced in the lower parts and are closely spaced in the upper parts.
• The contours are widely spaced in the upper parts and are closely spaced in the lower parts.
• The contours representing this type of slope are far apart.
• The contours are closely spaced Answer:
  • Concave Slope
  • Convex Slope
  • Gentle Slope
  • Steep Slope.

In This Post we are  providing  CHAPTER 1 INTRODUCTION TO MAPS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON INTRODUCTION TO MAPS

Question 1.
What are the basic limitations of maps?
Answer:
Map is two dimensional. It is impossible to present the accurate shape of the earth with the help of map. Moreover, it can’t be accurate in terms of area, volume and distance. Above all, we cannot show the entire earth on a map without disturbing its shape.

Question 2.
When was oldest map drawn?
Answer:
The oldest map was found in Mesopotamia drawn on a clay tablet that belongs to 2,500 B.C.

Question 3.
Why are maps considered an important tool for geography?
Answer:
Geographers need maps for following purposes:

• To get information about resources, their development and planning for their utilization;
• To study changes that are taking place on the earth;
• To understand various physical factors;
• To understand the inter-relationship between physical and human resources;
• To make a comparative analysis and
• To present facts in a way that has a memorizing effect.

Question 4.
How is area of map measured using a planimeter?
Answer:
The area calculation is also carried out using Polar Planimeter. In this instrument, a measure is made of the movement of a rod whose locus is constrained by having one end fixed to a radial arc. The area to be measured is traced along its perimeter in a clockwise direction with an index mark, starting from one convenient point to which the index of the tracing arm must exactly return. Reading on the dial, before and after the tracing of area’s perimeter, will give a value in instrumental units. These readings are multiplied by the same constant for the particular instrument to convert into areas in square inches or centimetres.

Question 5.
How is direction of map measured?
Answer:
Direction is defined as an imaginary straight line on the map showing the angular position to a common base direction. The line pointing to the north is zero direction or the base direction line. A map always shows the north direction. All other directions are determined in to this relation. The north direction enables the map- user to locate different features with respect to each other. The four commonly known directions are North, South, East and West. These are also called the cardinal points. In between the cardinal points, one may have several intermediate directions.

Question 6.
How is distance between maps measured by geographer, planner and other resource researcher?
Answer:
The linear features shown on the maps fall into two broad categories, i. e. straight lines and erratic or zigzag lines. The measurement of straight line features like roads, railway lines and canals is simple. It can be taken directly with a pair of dividers or a scale placed on the map surface. However, distances are required, more often, along erratic paths, i.e. the coastlines, rivers and streams. The distances along all such features can be measured by placing a thread at the starting point and carrying it along the line up to the end point. The thread is then stretched and measured to determine the distance. It can also be measured by using a simple instrument called Rotameter. The wheel of the ‘rotameter’ is moved along the route to measure the distance.

Question 7.
Explain in detail about physical maps.
Answer:
Physical maps: Physical maps show- natural features such as relief, geology, soils, drainage, elements of weather, climate and vegetation, etc. These are of following types:

1. Relief Maps: Relief maps show general topography of an area like mountains and valleys, plains, plateaus and drainage.
2. Geological maps: Geological Maps are drawn to show geological structures, rock types, etc.
3. Climatic Maps: Climatic Maps depict climatic regions of an area. Besides, maps are also drawn to show the distribution of temperature.

Question 8.
Explain the essentials of map making.
Answer:
There are five essentials of map making. These are: Scale, map projection, map generalisation, map design and map construction and production.

1. Scale: All maps are reductions. The first decision that a map-maker has to take is about the scale of the map. The choice of scale is of utmost importance. The scale of a map sets limits of information contents and the degree of reality with which it can be delineated on the map.

2. Projection: Maps are a simplified representation of the three-dimensional surface of the earth on a plane sheet of paper. The transformation of all-side- curved-geoidal surface into a plane surface is another important aspect of the cartographic process. Such a radical transformation introduces some unavoidable changes in directions, distances, areas and shapes from the way they appear on a geoid. A system of transformation of the spherical surface to the plane surface is called a map projection. Hence, the choice, utilisation and construction of projections is of prime importance in map-making.

3. Generalisation: Every map is drawn with a definite objective. For example, a general purpose map is drawn to show information of a general nature such as relief, drainage, vegetation, settlements, means of transportation, etc. Similarly, a special purpose map exhibits information pertaining to one or more selected themes like population density, soil types or location of industries. It is, therefore, necessary to carefully plan the map contents while the purpose of the map must be kept in the forefront.

4. Map Design: It involves the planning of graphic characteristics of maps including the selection of appropriate symbols, their size and form, style of lettering, specifying the width of lines, selection of colours and shades, arrangement of various elements of map design within a map and design for map legend.

5. Map Construction and Production: The drawing of maps and their reproduction is the fifth major task in the cartographic process. It can be manual or computerised method.

Question 9.
How does a geographer measure the distance?
Answer:
The measurement of area of features like that of administrative and geographic units is also carried out over the surface of the map by map-users. There are different methods in which areas can be determined.

1. By means of regular pattern of squares: In this method, the area to be measured is covered by squares by
placing a sheet of graph paper beneath the map on an illuminated tracing table or by tracing the area onto the square sheet. The total number of ‘whole squares’ are summed up, together with ‘partial squares’. The area is then determined by a simple equation:

2. By using Polar Planimeter: In this instrument, a measure is made of the movement of a rod whose locus is constrained by having one end fixed to a radial arc. The area to be measured is traced along its perimeter in a clockwise direction with an index mark, starting from one convenient point to which the index of the tracing arm must exactly return. Reading on the dial, before and after the tracing of area’s perimeter, will give a value in instrumental units. These readings are multiplied by the same constant for the particular instrument to convert into areas in square inches or centimetres.

Question 10.
Explain in detail about cultural maps.
Answer:
Cultural Maps: Cultural maps show man-made features. These include a variety of maps showing population distribution and growth, sex and age, social and religious composition, literacy, levels of educational attainment, occupational structure, location of settlements, facilities and services, transportation lines and production, distribution and flow of different commodities.

• Political Maps: These maps show the administrative divisions of an area such as country, state or district. These maps facilitate the administrative machinery in planning and management of the concerned administrative unit.
• Population Maps: The population maps are drawn to show the distribution, density and growth of population, age and sex composition, distribution of religious, linguistic and social groups, occupational structure of the population, etc.
• Economic Maps: Economic maps depict production and distribution of different types of crops and minerals, location of industries and markets, routes for trade and flow of commodities.
• Transportation Maps: These maps show roads, railway lines and the location of railway stations and airports.

In This Post we are  providing  CHAPTER 7 NATURAL HAZARD AND DISASTERS NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON NATURAL HAZARD AND DISASTERS

Question 1.
Differentiate between:
1. Natural Hazards and Natural Disaster.
2. Manmade disaster and Natural
Answer:
1.

Basis	Natural Hazards	Natural disaster
Meaning	Natural Hazards are elements of circumstances in the Natural environment that have the potential to cause harm to people or property or both.	Natural Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property including death and injury to a large number of people, and requires therefore, mobilisation of efforts in excess of that which are normally provided by statutory emergency services.
Scope	Every natural hazard is not a disaster.	Every natural disaster is a natural hazard.
Example	USA facing -50 degree temperature every year. It is a hazard but due to preparedness, it never becomes a disaster.	Tsunami occurred in 2004 proved to be a great disaster.

2.

Basis	Manmade Disaster	Natural disaster
Meaning	Manmade disasters are undesirable occurrences resulting from human actions.	Natural Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property.
Example	Bomb blast, industrial explosions, wars, fire accidents, etc.	Earthquake, landslides, cyclones, floods, droughts, etc.

Question 2.
Explain about different types of drought.
Answer:
Different types of droughts are as follows:

• Meteorological Drought: It is a situation when there is a prolonged period of inadequate rainfall marked with mal-distribution of the same over time and space.
• Agricultural Drought: It is also known as soil moisture drought, characterised by low soil moisture that is necessary to support the crops, thereby resulting in crop failures. Moreover, if an area has more than 30 percent of its gross cropped area under irrigation, the area is excluded from the drought-prone category.
• Hydrological Drought: It results when the availability of water in different storages and reservoirs like aquifers, lakes, reservoirs, etc. falls below what the precipitation can replenish.
• Ecological Drought: When the productivity of a natural ecosystem fails due to shortage of water and as a consequence of ecological distress, damages are induced in the ecosystem. Various parts of India experience these droughts recurrently which result in some serious socio-economic and ecological problems.

Question 3.
On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into how many zones?
Answer:
On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into a number of zones.

1. Very High Vulnerability Zone: Highly unstable, relatively young mountainous areas in the Himalayas and Andaman and Nicobar, high rainfall regions with steep slopes in the Western Ghats and Nilgiris, the north-eastern regions, along with areas that experience frequent ground-shaking due to earthquakes, etc. and areas of intense human activities, particularly those related to construction of roads, dams, etc. are very highly vulnerable.

2. High Vulnerability Zone: Areas that have almost similar conditions to those included in the very high vulnerability zone are also included in this category. All the Himalayan states and the states from the north-eastern regions except the plains of Assam are included in the high vulnerability zones.

3. Moderate to Low Vulnerability Zone: Areas that receive less precipitation such as Trans-Himalayan areas of Ladakh and Spiti, undulated yet stable relief and low precipitation areas in the Aravali, rain shadow areas in the Western and Eastern Ghats and Deccan plateau also experience occasional landslides. Landslides due to mining and subsidence are most common in states like Jharkhand, Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.

4. Other Areas: The remaining parts of India, particularly states like Rajasthan, Haryana, Uttar Pradesh, Bihar, West Bengal, Assam and Coastal regions of the southern States are safe as far as landslides are concerned.

Question 4.
Development may be disastrous. How?
Answer:
When the drive for economic growth occurs without regard to hazard profiles, existing mitigation technologies, and ongoing risk reduction programs, an increase in overall disaster risk results. Unsafe and unwise development practices lead to increased and additional risk factors, and often times result in an elimination of existing man¬made and natural risk protections. For example, in many coastal communities where development of the tourism infrastructure leads to the destruction of coral reefs, mangrove forests, wetlands, and dunes, natural protections from storm surges and tsunamis disappear. In the aftermath of the 2004 tsunami in Asia, was wide evidence that the destruction of these natural resources led to increased devastation in some areas over others where the protection was maintained.

Question 5.
Why do the rich countries and the poor countries differ so much in terms of the nature of their disaster consequences?
Answer:
Poor people, and likewise poor countries, tend to be much more vulnerable to events that exceed their capacity to withstand disaster impacts and to respond once a disaster has occurred. They are also much less likely to effectively recover in the aftermath of a disaster event.

1. The interaction between exposure and vulnerability can explain a lot about a country’s disaster profile. The instructor can illustrate the relationship between disasters and vulnerability by providing the students with an example of similar disaster events that occur in two different countries – one that is wealthy and one that is poor.

2. In most wealthy countries, an event of this magnitude causes little damage, very few injuries, and rarely any fatalities. However, in poor countries, it is not uncommon for a seismic event of this scale to cause significant injuries and fatalities.

3. In the wealthy countries, where buildings are constructed to code, and enforcement is effective, vulnerability is low to a magnitude 6.0 event. However, in poor countries, it is not uncommon for structures to be built in an informal fashion (out of traditional materials, including mud and stone, for example), with no consideration or enforcement of resistant building codes. In the event of a moderate earthquake, such as a 6.0 magnitude event, these informal structures can collapse.

4. It is poverty, and the many factors associated with poverty (such as corruption, poor access to building skills, knowledge, and materials, and other reasons), that create the vulnerability gap between the rich and the poor countries.

Question 6.
Disasters limit economic development. How?
Answer:
Disasters wipe out the gains of economic development. Examples include:

1. Hurricane Isaac (1982) – destroyed 22% of Tongo’s housing stock.

2. Mozambique Flood (2000) – resulted in over $165 million in costs to reconstruct and repair damage to water, sanitation, energy, telecommunication, roads and railway infrastructure.

3. Vietnam Flooding – each year in Vietnam, flooding destroys an average of 300,000 tons of food. Catastrophic disasters result in the destruction of a nation’s assets, and interrupt production, trade, investment, and other economic engines. Larger countries, with a greater geographical spread of economic assets relative to the spatial impact of disasters, are more able to avoid direct loss and minimize downstream, indirect or secondary losses.

Question 7.
How can man survive with earthquakes?
Answer:
Man can survive with earthquakes by taking following precautions:

• When earthquake occurs we should leave the house. If it is not possible to go out of the house stand in four corners of the walls or get inside bed, table etc.
• Switch off all electricity connections in the house.
• There should not be any fire. Put off all types of fire like gas stove must be switched off.
• Never drive any vehicle during earthquake.

Question 8.
Explain about disaster management in short.
Answer:
Disasters Management refers to the series of actions undertaken due to cyclones, unlike the ones caused by earthquakes, tsunamis and volcanic eruptions are more predictable in terms of the time and place of their occurrences.

Moreover, with the help of development of techniques to monitor the behaviour of cyclones, their intensity, direction and magnitude, it has become possible to manage the cyclonic hazard to some extent. Construction of cyclone- shelters, embankments, dykes, reservoirs and afforestation to reduce the speed of the winds are some of the steps that can help in minimizing the damages.

• Pre-disaster management involves generating data and information about the disasters, preparing vulnerability zoning maps and spreading awareness among the people about these.
• During disasters, rescue and relief operations such as evacuation, construction of shelters and relief camps, supplying of water, food, clothing and medical aids, etc. should be done on an emergency basis.
• Post-disaster operations should involve rehabilitation and recovery of victims. It should also concentrate on capacity¬building in order to cope up with future disasters.

Question 9.
What are different stages of disaster preparedness and management?
Answer:
There are three stages involved in disaster mitigation and management:

1. Pre-disaster management: It involves generating data and information about the disasters, preparing vulnerability zoning maps and spreading awareness among the people about these. Apart from these, disaster planning, preparedness and preventive measures are other steps that need to be taken in the vulnerable areas.
2. During disasters: During disasters, rescue and relief operations such as evacuation, construction of shelters and relief camps, supplying of water, food, clothing and medical aids etc. should be done on an emergency basis.
3. Post-disaster operations: It should involve rehabilitation and recovery of victims. It should also concentrate on capacity-building in order to cope up with future disasters, if any.

Question 10.
Development can help in disaster management as well as cause management. Justify the statement.
Answer:
Efforts to build upon and improve the social and economic engines, infrastructure, and institutions within a country can either increase or decrease hazard exposure, hazard vulnerability, and risk.

• (i) Practices that incorporate risk reduction methodologies, such as stringent building codes, resistant materials, proper land use planning, and other important mitigation measures and practices, often reduce the likelihood of disaster events or the consequences that result when events do occur.
• Unwise, uncoordinated, or unsafe development can quickly and dramatically increase the disaster risk faced by the people of a country.
• Mass urbanization and coastal migration which occur with little regard to wise building practices – as is often seen in the megacities of the developing world – is a primary contributor to increased risk of development.

In This Post we are  providing  CHAPTER 5 NATURAL VEGETATION NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON NATURAL VEGETATION

Question 1.
“Natural vegetation is an outcome of climate.” Substantiate the statement by taking example of Indian vegetation.
Answer:
India is a land of great variety of natural vegetation. Himalayan heights are marked with temperate vegetation; the Western Ghats and the Andaman Nicobar Islands have tropical rain forests.

• Tropical evergreen forests are found in warm and humid areas with an annual precipitation of over 200 cm and mean annual temperature above 22°C. In these forests, trees reach at great heights up to 60 m or above. The semi¬evergreen forests are found in the less rainy parts of these regions.
• Tropical deciduous forests are spread over regions which receive rainfall between 70-200 cm.
• The moist deciduous forests are more pronounced in the regions which record rainfall between 100-200 cm. Dry deciduous forest covers vast areas of the country, where rainfall ranges between 70-100 cm.
• Tropical thorn forests occur in the areas which receive rainfall less than 50 cm. In mountainous areas, the decrease in temperature with increasing altitude leads to a corresponding change in natural vegetation.
• The Himalayan ranges show a succession of vegetation from the tropical to the tundra, with change in the altitude. Deciduous forests are found in the foothills of the Himalayas. It is succeeded by the wet temperate type of forests between an altitude of 1,000-2,000 m. In the higher hill ranges of north-eastern India, hilly areas of West Bengal and Uttarakhand, evergreen broad leaf trees such as oak and chestnut are predominant. Between 1,500-1,750 m, pine forests are also well-developed in this zone, with Chir Pine as a very useful commercial tree.

Question 2.
Mention the reasons for the decline of wildlife in India?
Answer:
Important reasons for the decline of Wildlife in India are-

• Industrial and technological advancement brought about a rapid increase in the exploitation of forest resources.
• More and more lands were closed for agriculture, human settlement, roads, mining, resources, etc.
• Pressure on forests maintained due to looping for fodder and fuel, wood and removal of small timber by the local people.
• Grazing by domestic cattle caused an adverse effect on wildlife and its habitat.
• Hunting was taken up as a sport by the elite and hundreds of wild animals were killed in a single hunt. Now commercial poaching is rampant.
• Incidence of forest fire.

Question 3.
According to the statistics received from state records, there are differences in forest area and actual forest cover. Explain.
Answer:
According to state records, the forest area covers 23.28 percent of the total land area of the country. It is important to note that the forest area and the actual forest cover are not the same. The forest area is the area notified and recorded as the forest land irrespective of the existence of trees, while the actual forest cover is the area occupied by forests with canopy.
Forest area is based on the records of the State Revenue Department, while the actual forest cover is based on aerial photographs and satellite imageries.

According to India State of Forest Report 2011, the actual forest cover in India is only 21.05 percent. Of the forest cover, the share of dense and open forests is 12.29 and 8.75 percent respectively. Both forest area and forest cover vary from state to state. Lakshadweep has zero percent forest area; Andaman and Nicobar Islands have 86.93 percent. Most of the states with less than 10 percent of the forest area lie in the north and northwestern part of the country. These are Rajasthan, Gujarat, Punjab, Haryana and Delhi.

States with 10-20 percent forest area are Tamil Nadu and West Bengal. In Peninsular India, excluding Tamil Nadu, Dadra and Nagar Haveli and Goa, the area under forest cover is 20-30 percent. The northeastern states have more than 30 percent of the land under forest. Hilly topography and heavy rainfall are good for forest growth. There is a lot of variation in actual forest cover, which ranges from 9.56 percent in Jammu and Kashmir to 84.01 percent in Andaman and Nicobar Islands.

Question 4.
On the basis of actual forest cover, in how many categories have Indian states been divided?
Answer:
On the basis of the percentage of the actual forest cover, the states have been grouped into four regions:

• The region of high concentration > 40: It includes Andaman and Nicobar islands, Mizoram, Nagaland, Arunachal Pradesh which have 80% of their total area under forests. Manipur, Tripura, Meghalaya, Sikkim and Dadar and Haveli have forest cover between 40-80%.
• The region of medium concentration 20-40: It includes Madhya Pradesh, Odisha, Goa, Kerala, Assam and Himachal Pradesh. In Goa, actual forest cover is 33.27% which is highest in this range. Thereafter, comes Assam and Orissa. In other states 30% of their area is covered with forests.
• The region of low concentration 10-20: It includes states of Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Bihar and Uttar Pradesh.
• The region of very low concentration < 10: It includes states of Rajasthan, Punjab, Haryana, and Gujarat. It also includes union territories of Delhi and Chandigarh. It also includes West Bengal.

Question 5.
Explain in short about four important Biospheres of India.
Answer:
Four Biosphere Reserves have been recognised by the UNESCO on World Network of Biosphere Reserves. These are as follows:

1. Nilgiri Biosphere Reserve: The Nilgiri Biosphere Reserve (NBR) is the first of the fourteen biosphere reserves of
India. It was established in September 1986. It embraces the sanctuary complex of Wyanad, Nagarhole, Bandipur and Mudumalai, the entire forested hill slopes of Nilambur, the Upper Nilgiri plateau, Silent Valley and the Siruvani hills. The total area of the biosphere reserve is around 5,520 sq. km. The largest south Indian population of elephant, tiger, gaur, sambar and chital as well as a good number of endemic and endangered plants are also found in this reserve. The topography of the NBR is extremely varied, ranging from an altitude of250 m to 2,650 m. About 80 percent of the flowering plants reported from the Western Ghats occur in the Nilgiri Biosphere Reserve.

2. Nanda Devi Biosphere Reserve: The Nanda Devi Biosphere Reserve is situated in Uttarakhand. It includes parts of Chamoli, Almora, Pithoragarh and Ba’geshwar districts. The major forest types of the reserve are temperate. A few important species are silver weed and orchids like latifolie and rhododendron. The biosphere reserve has a rich fauna like the snow leopard, black bear, brown bear, musk deer, snow- cock, golden eagle and black eagle.

3. Sunderbans Biosphere Reserve: It is located in the swampy delta of the river Ganga in West Bengal. It extends over a vast area of 9,630 sq. km and consists of mangrove forests, swamps and forested islands. Sunderbans is the home of nearly 200 Royal Bengal tigers. More than 170 birds species are known to inhabit these mangrove forests. In the Sunderbans, the mangrove forests are characterised by Heritiera fomes, a species valued for its timber.

4. Gulf of Mannar Biosphere Reserve: The Gulf of Mannar Biosphere Reserve covers an area of 105,000 hectares on the south-east coast of India. It is one of the world’s richest regions from a marine biodiversity perspective. The biosphere reserve comprises 21 islands with estuaries, beaches, forests of the nearshore environment, sea grasses, coral reefs, salt marshes and mangroves.

Question 6.
“Forest and tribal are very closely related”. Justify the statement.
Answer:

• To a vast number of tribal people, the forest, is a home, a livelihood, their very existence.
• It provides them food, fruits of all kinds, edible leaves, honey nourishing roots and wild game.
• It provides them with material to build their houses and items for practising their arts.
• The importance of forests in tribal economy is well-known as they are the source of sustenance and livelihood for tribal communities.
• The age old knowledge of tribals regarding forestry can be used in the development of forests.
• Rather than treating tribals as minor forest produce collectors they should be made growers of minor forest produce and encouraged to participate in conservation.

Question 7.
When was comprehensive Wildlife Act enacted and what are its objectives?
Answer:
In 1972, comprehensive Wildlife Act was enacted.

• To provide protection to the endangered species listed in the schedule of the act.
• To provide legal support to the conservation areas of the country classified as national parks, sanctuaries and closed areas.
• Making punishments more stringent and has also made provisions for the protection of specified plant species and conservation of endangered species of wild animals.

Question 8.
Write the objectives of Project Tiger and Project Elephant and in how many states they are implemented.
Answer:
The objectives of Project Tiger and Project Elephant are:

• Maintenance of viable population of tigers in India for scientific, aesthetic, cultural and ecological values.
• To preserve areas of biological importance as natural heritage for the benefit, education and enjoyment of the people.

The Project Tiger was launched in 1973 under which 27 tiger reserves have been set up in 17 states.
Project Elephant was launched in 1992. 14 elephant reserves have been set up during the year. Its main objective to ensure long-term survival of identified viable population of elephants in their natural habitat.

Question 9.
What is Biosphere Reserve and what are its objectives?
Answer:
Biosphere Reserve is a unique and representative ecosystem of terrestrial and coastal areas which are internationally recognized within the framework of UNESCO Man and Biosphere (MAB) programme.
The main objectives of biosphere reserve are:

• Conservation: Conservation of biodiversity and ecosystem.
• Development: Association of environment with development.
• Logistics: International network for research and monitoring.

Question 10.
Mangrove forests are unique in their own way. Explain.
Answer:
Mangrove forest:

• The tidal forests are found in the areas of the coastal margins of Krishna, Kaveri, and Brahmaputra delta mainly occupying the estuaries, etc.
• They are found in the swamp and marshy areas.
• They can survive both in fresh and salty water.
• The trees have stilt like breathing or support rots, sticking out of mud and water.
• They are exposed at low tides and get submerged at high tides.
• Hot and wet climate favours their dense growth.
• Sunderi is the well known Mangrove trees. The famous Sunderban deltas are named after these trees.

In This Post we are  providing  CHAPTER 3 DRAINAGE SYSTEM NCERT MOST IMPORTANT QUESTION for Class 11 GEOGRAPHY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These   can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTION ON DRAINAGE SYSTEM

Question 1.
Differentiate between:
(a) Himalayas rivers and the Peninsular rivers.
Answer:
Difference between Himalayas Rivers and the Peninsular rivers.

Aspects	Himalayan rivers	Peninsular rivers
Place of origin	Himalayan mountains covered with glaciers	Peninsular plateau and central highland
Nature of flow	Perennial; receive water from glacier and rainfall	Seasonal, dependent on monsoon rainfall
Type of drainage	Antecedent and consequent leading to dendritic pattern in plains.	Super imposed : rejuvenated resulting in trellis and rectangular pattern
Nature of river	Long course, flowing through the mountains. Experiencing headwater erosion and river capturing in plains meandering and shifting of course.	Smaller, fixed course with well adjusted valleys.
Catchment area	Very large basins	Relatively smaller basin
Area of river	Young and youthful, active and deepening of the valleys.	Old rivers with graded profile, and have almost reached their base levels
Examples	Indus, Ganges and Brahmaputra and their tributaries.	Peninsular Plateau Chambal, Betwa, Central Highlands, Godavari, Krishna, etc.

(b) Consequent rivers and Antecedent rivers
Answer:
Difference between Consequent rivers and Antecedent rivers

Basis	Consequent rivers	Antecedent rivers
Shape	These rivers maintain their original shapes, deposits, the rise of land due to folding. The rivers keep on following in the same direction.	It is an uplift area the rivers flow in the direction resulting as consequent of the slope
Age	These rivers are older than the old mountain.	These rivers are formed after the uplift of an area.

Gorges	These rivers cut deep gorges due to down cutting.	These rivers do not form gorges.
Examples	Trans- Himalayan rivers such as Indus, Satluj, represent consequent rivers.	The eastward flowing river of peninsular plateau which flow according to the slope are antecedent rivers.

Question 2.
Differentiate between canyon, gorge and river valley.
Answer:
A canyon is a deep valley with steep sides, think of the grand canyon most famously to visualise what this is. A gorge is a deep ravine, which usually has a river running through it—though this doesn’t have to be the case. Finally a valley is any depression, usually of a certain length, in the surface of the land and often contains a river. So, a canyon is a specific type of valley, with particularly steep sides. A gorge is a particularly deep depression, and will usually contain a river.

Question 3.
What makes a river system? Explain its components.
Answer:
River system

• A river is a body of water, which flows into channel from a higher elevations to a lower elevation rivers usually originate from lake or melting snow on top of mountains flow down hill and join sea or ocean. The place from where the river originates is known as the source, and where it ends is known as the mouth.
• From the source , the river flows along a path which is known as its course. The course of a river can be divided into three parts, the upper course, the middle course and the lower course.
• In the upper course, the river flows with great force through a narrow and shallow channel. Only a small amount of water is transported. The gradient slope of river is very steep.
• In the middle course, the force of the river reduces its flow through gentle gradient such as plains. Many small stream or river join the main river in the middle course resulting in widening of the river channel. The small streams are known as tributaries.
• The river finally flows into lake, sea or ocean. The part of the river that enters the sea is known as the river mouth.
• A river and its tributaries together form a drainage basin. A drainage basin is an area obtained by two main river and its tributaries and drainage basin is separated from adjacent basins by a hill, a ridge or mountain which is known as a drainage divide or watershed.

Question 4.
What factors affect speed of a river?
Answer:
Factors affecting the speed of a river: The main factor affecting the speed of a river are the gradient and roughness of the channel and the wetled perimeter gradient.

1. Gradient: It refers to the drop in elevation of the river channel as the river flows down the hill. If the gradient is steep, the rivers flow quickly, whereas if the gradient is gentle the river flows slowly. In the upper course, the river flows rapidly through a steep gradients. On the other hand, the middle and the lower course, the river flows gently through a greater gradient.

2. Roughness: As water flows through a river channel; it encounters obstacles such as rocks, boulders, numerous river bed and underwater vegetation obstacles cause friction between the river and the channel. Rougher channels will reduce the speed of the river due to the higher friction.

3. Wetled perimeter: When the wetled perimeter is large, more water comes in contact with the channel causing more friction. When the friction is high the flow of the river becomes slow on the other hand when the wetled perimeter is small, less water flow along the channel causing less friction. When the friction is less, flow of water is fast.

Question 5.
Explain the evolution of Himalayan river system.
Answer:
There are difference of opinion about the evolution of the Himalayan river system. However, geologists believe that a mighty river called Shiwalik or Indo-Brahma traversed the entire longitudinal extent of the Himalaya from Assam to Punjab and onwards to Sind, and finally discharged into the Gulf of Sind near lower Punjab during the Miocene period some 5-24 million years ago. The remarkable continuity of the Shiwalik and its lacustrine origin and alluvial deposits consisting of sands, silt, clay, boulders and conglomerates support this viewpoint.

The dismemberment was probably due to the Pleistocene upheaval in the western Himalayas, including the uplift of the Potwar Plateau (Delhi Ridge), which acted as the water divide between the Indus and Ganga drainage systems. Likewise, the down-thrusting of the Malda gap area between the Rajmahal hills and the Meghalaya plateau during the mid-pleistocene period, diverted the Ganga and the Brahmaputra systems to flow towards the Bay of Bengal.

Question 6.
Explain the evolution of Peninsular drainage system
Answer:
Three major, geological events in the distant past have shaped the present drainage systems of Peninsular India:

• Subsidence of the western flank of the Peninsula leading to its submergence below the sea during the early tertiary period. Generally, it has disturbed the symmetrical plan of the river on either side of the original watershed.
• Upheaval of the Himalayas when the northern flank of the Peninsular block was subjected to subsidence and the consequent trough faulting.
• Slight tilting of the Peninsular block from north-west to the south-eastern direction gave orientation to the entire drainage system towards the Bay of Bengal during the same period.

Question 7.
What are the problems associated with the use of river water?
Answer:
There are some problems in river water usage. Some of these are:

• No availability in sufficient quantity
• River water pollution
• Load of silt in the river water
• Uneven seasonal flow of water
• River water disputes between states
• Shrinking of channels due to the extension of settlements towards the thalweg.

Question 8.
What are the causes of pollution of river water?
Answer:
Major causes of pollution of river water:

• Growing Population,
• Poverty,
• Urbanization,
• Industrialization,
• Agricultural run-off and Improper Agricultural Practices, and
• Religious and Social Practices.

Question 9.
What measures do you suggest to reduce pollution of rivers?
Answer:
River pollution generally originates from industrial effluents, agricultural run-off and domestic sewage, which is resulting in environmental-economic loss to the country. Rapid industrialization and urbanization, accompanied by rural exodus to urban areas have had their evil consequences, generally on environment, and particularly on rivers. The law dealing with the task of prevention and control of river pollution, is needed to be set in motion along with public awareness about the importance of pollution free rivers, so that the rivers can be saved from the curse of pollution, and the precious money of the Government exchequer can be saved from expenditure on the river cleaning programmes.

Question 10.
Can the problems of flood and drought be solved or minimised by transferring the surplus water from one basin to the water deficit basins? Do we have some schemes of inter-basin linkage?
Answer:
Yes, these problems be solved or minimised by transferring the surplus water from one basin to the water deficit basins. During the rainy season, much of the water is wasted in floods and flows down to the sea. When there is a flood in one part of the country, the other area suffers from drought. We do have such schemes:

• Periyar Diversion Scheme
• Indira Gandhi Canal Project
• Kurnool-Cuddapah Canal
• Beas-Satluj Link Canal
• Ganga-Kaveri Link Canal