NCERT Solutions for Class 11 Geography Chapter 5 - Topographical Maps

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36. Answer the following questions in about 30 words:

(i) What are topographical maps?

Ans. The maps that are drawn at relatively large scales and show important natural and cultural features such as relief, vegetation, water bodies, cultivated land, settlements, and transportation networks, etc. These maps are also known as general purpose maps.

(ii) Name the organisation which prepares the topographical maps of India.

Ans. Topographical maps under India and Adjacent Countries Series were prepared by the Survey of India till the coming into existence of Delhi Survey Conference in 1937. Since that time, the creation of maps for the neighbouring nations has been discontinued, and the Survey of India has focused only on creating and publishing topographical maps of India in accordance with the guidelines established for the International Map Series of the World.

(iii) Which are the commonly used scales for mapping our country used by the Survey of India?

Ans. The topographical maps of India are prepared on 1:10,00,000, 1:250,000, 1:1,25,000, 1:50,000 and 1:25,000 scale providing a latitudinal and longitudinal coverage of 4° × 4°, 1° × 1°, 30 × 30, 15’ × 15’ and 5’ × 7’ 30”, respectively.

(iv) What are contours?

Ans. Contours are imaginary lines joining places having the same elevation above mean sea level. In other words, these are imaginary lines joining all the points of equal elevation or altitude above mean sea level. They are also called level lines”.

(v) What does the spacing of contours indicate?

Ans. A contour line is drawn to show places of equal heights. The spacing shows:

(a) Contour lines and their shapes represent the height and slope or gradient of the landform.

(b) Closely spaced contours represent steep slopes while widely spaced contours represent gentle slope.

(c) When two or more contour lines merge with each other, they represent features of vertical slopes such as cliffs or waterfalls.

(d) Two contours of different elevation usually do not cross each other.

(vi) What are conventional signs?

Ans. There are some internally determined standard symbols, signs and colours which are used to depict settlements, buildings, roads and railways are important cultural features shown on topographical sheets. When these features are exhibited through conventional signs, symbols and colours, it becomes easy to understand and interpret the map. Conventional Signs and symbols are internationally accepted so that anyone can read any map anywhere in the world without knowing the language of that particular country.

37. Write short notes on:

(i) Contours

Ans. (a) Contours are imaginary lines joining places having the same elevation above mean sea level. A contour map is one that uses contour lines to illustrate the landform of a particular area. The method of showing relief features through contour is very useful and versatile. The contour lines on a map provide a useful insight into the topography of an area.

(b) Earlier, contours on topographical maps were shown using ground surveys and levelling techniques. The customary techniques of surveying, levelling, and mapping have been supplanted by the development of photography and the use of aerial photography that followed. These images are now utilised in topographical mapping.

(ii) ‘Marginal Information’ in Topographical sheets.

Ans. The topographical sheet number, its position, grid references, its extent in degrees, and what precisely a topographical sheet is exhibiting are all examples of marginal information. It is impossible to interpret a topographical sheet in any way without this peripheral data.

(iii) The Survey of India

Ans. India’s topographical maps are created by the Survey of India for the whole nation. Up to the establishment of the Delhi Survey Conference in 1937, the Survey of India produced topographical maps for the India and Adjacent Countries Series. As a result, the creation of maps for the neighbouring nations was discontinued, and the Survey of India focused only on creating and publishing topographical maps of India in accordance with the guidelines established for the International Map Series of the World.

38. Explain what is meant by ‘map interpretation’ and what procedure is followed for its interpretation.

Ans. The study of factors that explain the causal relationship among several features shown on the map. Reading and understanding toposheets requires both familiarity with map terminology and a good sense of direction. To properly orient oneself, we must first search for the map’s scale and north line. The labels and key that are provided for the map’s numerous aspects must be thoroughly understood by us.

The following procedure is followed in map interpretation:

(a) Finding from the index number of topographical sheet and the location of the area in India. This would give an idea of the general characteristics of the major and
minor physiographic divisions of the area.

(b) Find the scale of the map and the contour interval, which will give the extent and general landform of the area.

(i) Major landforms: as shown by Contours and other graphical features.

(ii) Drainage and water features: the main river and its important tributaries.

(iii) Land use: i.e., forest, agricultural land, wastes, sanctuary, park, school, etc.

(d) Explain the distributional pattern of each of the features separately drawing attention to the most important aspect.

(e) Superimpose pairs of these maps and note down the relationship, if any between the two patterns. For example if a contour map is superimposed over a land use map, it provides the relationship between the degree of slope and the type of the land used.

(f) Aerial photographs and satellite imageries of the same area and of the same scale can also be compared with the topographical map to update the information.

39. If you are interpreting the cultural features from a topographical sheet, what information would you like to seek and how would you derive this information? Discuss with the help of suitable examples.

Ans. Settlements, occupation, means of communication and transportation, land use pattern are some of the cultural features which are shown on topographical sheet using conventional signs, colour and symbol. We will seek the information about these features.

(a) 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.

(b) Settlement:

(i) Rural Settlements: The types and patterns of rural settlements, i.e., compact, semi-compact, dispersed, linear, etc.

(ii) Urban Settlements: Type of urban settlements and their functions, i.e., capital cities, administrative towns, religious towns, port towns, hill stations, etc.

(c) 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 practiced. Similarly, in cities and towns, services and business appear to be the major occupations of the people.

40. Draw the conventional signs and symbols for the following features:

(i) International Boundary

(ii) Bench Mark

(iii) Villages

(iv) Metalled Road

(v) Footpath with bridges

(vi) Places of Worship

(vii) Railway line

Ans.

(i) International Boundary =

(ii) Bench Mark =

(iii) Villages =