smaller the scale, greater the interval ratio.įunds available: Lower the contour interval, the greater amount of work. The scale of the map: The contour interval should be the inverse ratio of the scale i.e. Where the large interval is used in large areas compared to less important works. Purpose of the survey: If the area is to be surveyed is small the contour interval is also small e.g. If it’s not large the contours will come too close. In another hand, which countries have hilly region the contour intervals are large. Nature of Ground In those countries which have flat and uniform sloping ground, the contour interval is small. There are various factors in contour surveying on which the selection of the appropriate contour interval depends. Factors affecting the selection of Contour Interval For example t22r04ctr005 indicates contours for the township 24, range 04. The horizontal distance between the two adjacent contours is called horizontal equivalent. Contour isolines with interval in feet as defined by numerical suffix to data tile. The variable contour interval gives a false impression of the relative steepness of the surface in different parts of the map. We should use a constant contour interval through a map. The constant vertical distance between any two consecutive contours is called the contour interval. So contour map serves both, a plan and a section of that area. It also produces a plan of that particular portion. Here we can easily access the altitudes of the earth surface. A contour line consists of the same points so all the same points exist in a single contour line. The line which passes through saddles is called the watershed line.Ĭontour line can’t be a break, it must be continuous. It represents the junction of two ridges or a dip in a ridge. Four sets of contours are represented here. Depression between summits is called a saddle.Contour lines never run into one another unless there is a vertical cliff.Contour lines are not cross to each other whether there is an overhanging cliff.Contour lines can’t end anywhere but close on themselves or outside the map limit.If the higher value is inside it indicates ‘Ridge’ or if a higher value is outside the bend it denotes ‘Valley’. Contour lines are right angle in the valley or ridge portion.A series of closed contour lines are indicating depression if the higher value is outside.A series of contour line which is closed to each other indicated a hill and the higher value inside.Uniform slope is indicated by uniformed spaced contour line from each other and flat ground is indicated as a straight line, uniformed space and parallel to each other.Contour lines are far away from each other in a flat region and close to each other in the mountainous region.In contour surveying, all points in a contour line have the same elevation.So, each contour line has a separate and individual altitude concerning the assumed ground surface. It may also be defined as the intersection of the level surface at a particular ground level. To estimate the quantity if cutting-filling of soil and the capacity of a reservoir.Ī contour line or simply, ‘Contour’ is an imaginary line passing through points of equal elevation of the death surface.To determine the profile of the country in any direction.To determine the intervisibility of stations.In the selection of sites for new industrial plants.In planning and designing of dams, reservoirs, aqueducts, transmission lines, etc.In determining the location of water supply, water distribution and to solve the problem of steam pollution.In the proper and accurate location of engineering projects such as roads, canals, etc.Factors affecting the selection of Contour Interval Application of Contour Surveying in Civil EngineeringĬontour surveying is useful in civil engineering in the following areas: The contour interval is kept large When funds are limited and the contour interval is kept small when a fund is not a problem.3.1. If the contour interval is small, greater time Will be take in the field survey, in reduction and in plotting the map. If the time available is less, a greater contour interval should be used. The extent of the survey in such cases will generally be small in the case of location survey, for a line of communications and for reservoir and drainage areas, where the extent of the survey is large, a large contour interval is to be used. The contour interval largely depends upon the purpose and the extent of the survey.įor example, if the survey is intended for detailed design work or for accurate earthwork calculations, a small contour interval is to be used. Also Read : Something About Civil Engineering Design Software Purpose an Extent of The Survey
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |