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Numbering system of topographical map
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### Toposheet interpretation

1. 1) MAP: A map is a two dimensional surface drawn on a flat paper or sheet with length and breadth. All physical and cultural features are shown on the map with the help of certain symbols (conventional signs). A map is graphical and conventional representation of the distribution of physical and cultural phenomena of the earth surface drawn to a scale or representation of natural and man made features are plotted on a paper or a sheet with a scale is called a map. 2) SCALE:- A scale denotes the relationship between the length of a line on the map or sheet or paper and the length of that line on the ground. It is defined as the ratio between the distance between the two points on the map and corresponding distance on the ground. Large areas can be drawn on small sheet of paper with the help of a scale. Scale helps us to know the distances on the map. The ratio of a scale can be expressed in three ways A) By a statement or verbal scale. B) By an arithmetical representative fraction (R.F) C) By liner or graphical scale. A) VERBAL SCALE OR DIRECT STATEMENT: - Verbal scale gives the map and the ground ratio through a statement. Ex. One inch to four miles. It is evident from this example that one inch on the map represents four miles on the ground. Such scale is very simple and readily understood. A verbal scale involves a statement expressing the relationship between the map and the ground through particular type of measurement system. Such system may differ from one country to another.
2. B) REPRESENTATIVE FRACTION(R.F): - It is popularly known as scale or ratio between the map and ground is expressed in the form of an arithmetical ratio or fraction in which the map is represented by the numerator which is always one and the ground by denominator which is an equal number of similar units. Ex. 1cm:100 meters, 1inch:1000ft. This scale can be denoted as 1/100 or 1/1000 = 1:10 C) LINEAR OR GRAPHICAL SCALE: - It is a straight line of convenient length. It is divided in to equal division of 1 inch representing 1 mile. 0 1 2 3 0 1 2 3 The figure ‘0’ is not placed at the extreme left hand end but at right hand end on the first division.
3. GRID REFERENCE: Four figure grid reference consists of four digits. The 1st two digits are of easting and last two digits are of northing. The Eastward lines or vertical lines drawn on the survey sheets are called Easting. Northward lines or horizontal lines drawn on the survey sheets are called Northing. A network of easting and northing forms number of squares called Grids. The left hand corner of the grid represents each grid for reference. Easting are always quoted first then northing. These lines are black or red in colour. Easting Northing N S EW N W N E S W S E
4. EXTENT OF THE MAP: - LONGITUDES: - The lines of longitudes are called meridians. They are imaginary lines or semicircles drawn on the earth surface in north/ south direction. The word meridian being derived from a Latin word meaning Mid-day. All places on the same meridian of longitude have mid day at the same day. The earth circumference consists of 360º so we can draw 360º longitudes. The meridian or longitude passing through the Greenwich is 0º and is called standard meridian or prime meridian. All other degrees of longitude are drawn to the East or West of the prime-meridian. There are 180º of longitudes towards East or East longitude and 180º towards West or West longitude. The 180º is common for East or West. Each degree of longitude cuts the latitude at the right angle ie, 90º W E E W N S
5. LATITUDE:- Lines of Latitude are the circles drawn round the earth parallel to the equator. The parallel of latitude is an imaginary circle drawn east /west on the surface of the earth. The circle of latitude that divides the earth in to two hemispheres and is exactly at equal distance from the pole is called equator. The other circles of latitude are drawn to the North or South but parallel to this circle. As the earth is a sphere the angular distance from the equator to the pole is 90º so we have 90º of latitude from the equator to the North pole in the Northern hemisphere. 90º of latitude from the equator to the South pole in the Southern hemisphere. All the degrees of latitudes are circles except the poles which are mere points or straight line. All these circles are parallel to each other and to the equator. They are equi-spaced or the distance between any two consecutive degrees of latitudes is the same. N S W 0 0 EEqu ator Latitu de
6. COLOUR REPRESENTATION IN THE MAPS - Various colours are used to show different features on the survey sheet. Yellow colour- represents cultivated area Green colour- represents forest. Blue colour- represents water bodies Black colour- represents boundaries and railway lines Brown colour- represents contour lines and sand dunes. Red colour- represents buildings and roads. Prominent survey trees are black coloured.
7. RELIEF OR TOPOGRAPHY: Relief or topographycan be shown on the map by 1. Hashing (without contours) 2. Hill shading (with contours) 3. contour lines 4. form lines 5. spotheights 6. triangular stations, BM (bench mark) 1. HACHURING – hachure are short lines representing the way in which water would flow from high land to low land. On steep slopes they are closer together than the gentle slopes, but on the flat ground there are none at all. It gives no indication of the actual height. Both plateau and low plains are not shaded. Hachuring gives modeled appearance and relief features stand out clearly. 2. HILL SHADING (WITH CONTOURS) – The steep slopes are then shown by dark-shading. Plain lands and plateau are not shaded. Shading shows inclination or slope of the ground. In non shaded area the ground is almost flat. It does not give actual height and also which side is sloping either up hill or down hill side.  Hill-shading gives modeled appearance of relief of light and dark shade. 3. CONTOUR LINES – A contour line is a line joining all places which are at the same height above mean sea level. Or these are lines drawn on the sheet which join together all the places having the same height above the mean or average sea level (MSL). They are numbered and drawn in black or brown colour. All the contour patterns on the map represents landscape, some relief features namely concaveslope, valley, spur, ridge, escarpment and plateau, occurfrequently on the surface of the earth.
8. For representing relief features by contours it will be helpful to remember following points.  When contours are widely separated that indicates plane or table land or flat land with gentle slope and when they are closely spaced they represent steep slope.  They go on coming closer together all the slope become steeper and steeper until they merge in to each other when the slope is almost vertical.  Contours do not cross each other.  A contour is a smooth line without numerous bends.  They conform to the slope of the ground which they represent. 1. Uniform slope. 2. Concave slope. 3. Convex slope. 4. Terraced slope. 5. Undulating slope. 6. Conical slope. 7. Plateau. 8. V-shaped valley. 9. Spur 10. Escarpment. 4. FORM LINES –Sometimes accurate survey is not possible in hilly areas. Form lines are used instead of contours. These are broken lines but not numbered. They help to show minor details. 5. SPOT HEIGHTS OR BENCH MARKS - These are dots plotted on the survey sheet showing the exact height of a point above the sea level. They are plotted after actual survey of the area. These are shown in black colour. Ex: .200 or .BM200 6. TRIANGULAR HEIGHT OR TRIGONOMETRIC STATION – These are plotted on the survey sheet in black colour and show the exact height of peaks after actual survey of the area. These provide more accurate height with contours and spot height. Ex. △200
9. SETTLEMENT PATTERN : There are five types of settlement pattern. 1. NUCLEATED OR CLUSTERED - Buildings or houses are constructed in a compactmanner and are very close to each other. Mostly near the wells or tanks or bore wells etc. 2. SCATTERED OR DISPERSED - Buildings or houses are scattered everywhere (isolated) away from each other. 3. LINEATED OR RIBBONED - Buildings or houses are constructed along the road, river, canal or railway line. 4. RECTANGULAR PATTERN - Buildings or houses are constructed at cross roads. 5. STAR-SHAPED PATTERN - Buildings or houses are constructed around the big water bodies. DRAINAGE PATTERN- There are five types of drainage pattern. 1. DENDRITIC PATTERN – A number of tributaries join the main river or stream and make a pattern like veins of a leaf or branches of a tree or fingers on a hand. 2. TRELLIS PATTERN(RECTANGULAR) - A number of streams and tributaries join the main river at right angle. It looks like rectangular garden trellis. 3. RADIAL PATTERN – Streams and tributaries may flow in all directions from the highest section. They flow out word forming pattern like spokes of a wheel. 4. PARALLEL PATTERN – streams or tributaries flow parallel to each other. 5. DISAPPEARING PATTERN - Streams and tributaries disappear in to the soil before reaching the ocean or sea.
10. INTERPRETATION OF TOPOSHEET 1. Introduction 2. Relief or topography 3. Drainage 4. Mode of Transport 5. Settlement pattern 6. Climate 7. Vegetation 8. Occupation 1. INTRODUCTION- 1. The number of the toposheet given in the top right corner (Toposheet number). 2. Name of the area. 3. The district and state to which the area or map belongs. 4. Extent of the map ie. Latitudinal and longitudinal extent of the map. 5. Interval of parallel and meridian. 6. Extent of longitude and latitude. 7. Contour interval. 8. Total area in the given toposheet or total ground area. 9. Year of publication of the map. 10. Year of survey 11. Magnetic variation from the true north. 2. RELIEF OR TOPOGRAPHY - The physical features include plains, plateaus, hills, valleys with respect to direction in the map. Physical features can be interpreted based upon spacing of contour lines weather they are closely spaced or widely spaced. The highest or height can be known from the Bench mark △ station or spot height etc. 3. DRAINAGE- Name of the river or stream, flow direction, height of the bank, breadth of the canal, stage of river, meandering, River is seasonal or perennial, Drainage pattern, rock type. Appearance and disappearance of stream. Variation in the breadth of the river or straem. Name of the tributaries joining the river.
11. 4. SETTLEMENT PATTERN – Urban or rural 5. MODE OF TRANSPORT Number of metal, unmetal, cart tracks, railway lines connecting one place to another. 6.OCCUPATION- It is based on settlement pattern and mode of transport. If the map is yellow coloured the occupation of the people is agriculture. In the area where irrigation is available from wells, tanks, agriculture is intensive. If there is forest, some people may be engaged in burning of wood for making charcoal and collection of forest products. In mining area occupation of the people is mining. In the industrial belt,people will be industrial workers. 7. CLIMATE - 1. Coniferous trees suggest that climate is cool (Himalaya). 2. Deciduas vegetation indicates tropical or subtropical climate (dry and moist). 3. The presence of cactus, shrubs, dunes, virtual absence of streams suggest semidry climatic condition. 4. Forest, bamboo, tea-garden, beetle palm suggest moderate to heavy rainfall.
12. Ex. Toposheet No :- 47k/3 1. Introduction This map represents Poona, North Satara and Sholapur districts of Bombay state, Maharashtra. Longitude – 74 0 – 75 45 East Latitude – 17 45 – 18 0 North Parallel and meridian – 5 & 5 Extent of the map - 15 by 15 Total area in the given toposheet – 324 sq. miles Scale of the map – 1 inch to a mile or 1: 63,360 units. The area was surveyed in the year 1954-55. It was published by G.I.S. in the year 1957. Magnetic variation from the true north is about 1 ¾ west 1953. 2. Relief The map shows concentration of contours in the S-W direction of the map. The maximum elevation of the hill is 2534’. Contour interval is 50’. Besides there are small hills. Densely spaced contours indicate steep slope and is confined to S-W direction. The rest of the area is plain land or flat ground. 3. Drainage The main river is Neera which shows meandering and is flowing from West to East. The river is in the mature stage. Many tributaries joined the Neera river. Neera river and other small streams are the main source of water in this region. There are wells and canals for irrigation purpose. 4. Settlement Settlement is nucleated or clustered and scattered all over the area and is seen along the river bank. The area is thickly populated. In the given toposheet the area is urban as well as rural. 5. Transport and communication There are three metal and unmetalled roads. One metalled road connecting from Nateputa to Malsiras, second road connecting from Malsiras to Pativasti, Malsira to Khundus. Unmetalled roads connecting from Melsiras to Tirwandi and from Chitainagar to Umra. 6. Occupation The occupation of the people is agriculture as well as industrial workers which can make out by the type of settlement and relief or topography.