11/25/2023 0 Comments Whats a contour interval![]() ![]() In a given map the contour interval is a constant The distance must be measured on the map and converted to actual distance by multiplying with the scale of the map No measurement or scaling is required since the contour levels are indicated on the contour lines The difference between Contour intervals and Horizontal Equivalent are tabulated below: S. The horizontal distance between two points on two consecutive contour lines for a given slope is known as horizontal equivalent. Earthwork estimations for any type of structure like bridges, dams or roads can be found out with the help of contour intervals in a map.Īs contour intervals are for the calculation of vertical elevation of an area, same way to calculate the horizontal distance it is termed as Horizontal Equivalent.In this case, to find out the intermediate points elevation, contour intervals are used. In a large map, index contour lines are less to keep it simple to read the map easily.A higher contour interval is used for a large area and small contour interval for small area. When a large area is to be mapped in small piece of paper contour intervals are used.The Contour Interval of the above map us 20 Units. The number of contour lines in-between 70 are 4. Let’s assume, 70 and calculate the interval between it. The final answer we get after dividing is the contour interval of the specific topographical mapĮxample Calculation of Contour Intervals:Ĭonsidering the above map, the steps involved in contour interval calculation are, The final step is the quotient of the difference between 2 index lines (step 2) and the number of lines in between two index lines plus 1 (step 5). The number of lines obtained in the above step is taken and added with 1.įor Ex: If the number of lines between 2 index lines are 5. Now count the number of non-index lines contour lines between the 2 index contour lines selected for the contour interval calculating in the 1 st step. To take the difference, subtract the higher elevated line with the lower elevated line reading. Now calculate the difference between the two-selected index contour line selected from a map. The calculation of the contour intervals is as below:įirstly locate 2 index contour lines that are labeled with a specific elevation. In the above figure, the dark lines with reading are index contour lines. These marked or labeled lines are known or termed as Index Contour Lines. To keep the contour map simple and easy to read, not every contour line is marked with its elevation reading. How to Calculate Contour Interval from Maps?Ī contour map consists of contour lines of a given geographical region. If the ground has large variation in levels, for instance, hills and ponds If a detailed map is to be prepared for execution work Select Low CI like 0.5m, 0.25m, 0.1m or lessįor small scale maps covering a wide area of varying terrainįor rough topographical map meant for initial assessment only The selection of the contour interval is decided by the survey leader before the start of the mapping process depending upon the ground factors. The commonly used contour interval is 20 feet for a 1:24,000 map scale.įactors Affecting the Selection of Contour Interval When the contour interval is not specified in the map, it can be calculated as explained in the following sections. ![]() In every map, on the right-hand bottom side, the contour interval is specified. Considering the size of the area to be mapped, contour intervals are assumed. Usually there are different contour intervals for the different maps. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |