What are Contour Lines and Topographic Maps?.I hope I have covered all the topics related to contour. This is the complete information about contour. These are used for obtaining data used in the design and construction of irrigation structures such as dams.A military operation can be planned with the help of a contour map.Estimating the volume of reservoir storage water, the volume of earthwork in cutting and embankment can be done by using the contour map.It is possible to select the most suitable and economical sites for work such as the location of roads, railways, canals, pipelines, dams, reservoirs etc.flat, uniformly, sloping, undulating or hilly etc. Estimating the quantities of earthwork.Nature of ground surface may be determined.Alignment for roads, canals, transmission lines is done efficiently with the help of contour map.The suitable site can be selected for construction activities.The indirect method is cheaper, quicker and less tedious than the direct method. Determine the elevation of these points in the field.Establishing a definite pattern of ground points whose relative position are known.In this method levelling work is carried out in the field and location of contour points is done in the office. Plot the survey to a suitable scale on the paper.Carry out a survey to determine relative positions of these points of a contour line in the field.Repeat the procedure for other contours either with the same position or by shifting the instrument.Mark the points on the ground by pegs or coloured tags.Direct the staffman to move within the boundaries of the area so as to get the desired staff reading through the dumpy level.Calculate the staff reading required for a particular contour by the relation.ĭesired staff reading = HI – contour elevation.The fieldwork involved in this method is as follows. Now the contour can be plotted on the map. These points are thereafter surveyed and their positions in the horizontal plane are found out within given boundary. In this method, the contours are directly located on the ground and the points of given contour are marked on the ground. This method is tedious and time-consuming. There are two methods of locating contour Reservoir and town planning work – 0.5 to 1 m.Large scale maps pr flat country – 0.5 m.Small scale maps or rough country – 5m to 25 m.The following contour intervals may be adopted for various purpose. Considering the following factors on which contour interval depends Consideration in making the choice of the proper contour intervalīefore preparing a contour map, the contour interval required is decided. For small contour interval, the money required will also more as the field and office work will be more. The small contour interval, the survey work and plotting have to be more accurate. Large contour interval is to be used if the time available for the survey work is less. Time Available and Expense Admissible for the field and office work If the survey work is to be used for the accurate and detailed calculations, then the small contour interval is to be chosen and a large contour interval is chosen for the following cases:
The Purpose And The Extent of the Survey Work For sloping or undulating ground the contour interval is chosen should be large. For a flat area, the contour interval should be small. The general topography of the area decides the contour interval.
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