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"); Lag is a function of the flow length of the watershed, average land slope of the watershed, and the potential maximum retention of rainfall on the watershed. mGԂ�L��p�nC�-���� Required information includes watershed characteristics (drainage area, runoff curve number, watershed length, watershed slope) and rainfall amount and rainfall distribution. })*/ Lag is the delay between the time runoff from a rainfall event over a watershed begins until runoff reaches its maximum peak. Answers: 1 on a question: For a drainage area of Area= 38 km2, Stream length L = 12 km, average watershed slope Y = 3% and CN = 77. dom.query(this).attr("alt") : dom.query(this).attr("title").trim(); Same logic with 1/8″ slope, 1/16″ slope, etc. Haan et al. Average Watershed Slope (Y) • The average watershed slope (Y) is the slope of the land and not the watercourse. }else{ Draw the ‘L’ section of the main stream. stream }) }); If slope is more, the velocity is more, and hence flood water drains quickly results in higher peak discharge reduces infiltration increases the soil transportation 16. The topographic feature is one of the main factors that influence the process of soil erosion and sediment yield of small watershed . ���u�ɠ&��b�T�/A�(Ee�[iu�5R�����b))JQ��D�����+�H Watershed lag time equation calculator solving for average watershed slope given watershed lag time, watershed hydraulic length and potential watershed storage [CDATA[ It is considered an independent variable. The authors investigate the effect of digital elevation model (DEM) grid size and source on the average watershed slope. average watershed slope in a sentence - Use "average watershed slope" in a sentence 1. use the SCS dimensionless unit hydrograph. The initial steps to calculating slope either way are the same. Step 2. Calculating average slope of a watershed upstream of many points in ArcGIS (upstream basin slope) Ask Question Asked 3 years, 1 month ago. imgMarginTop = imgMarginTop.replace("px",""); Peak discharges range from 5 to 2,000 cubic feet per second (cfs), drainage areas range from 5 to 2,000 acres, and 24-hour rainfall depths range from 1 to 12 inches. The watershed slope, or average watershed land slope, is used in the lag equation to estimate the watershed Tc. } var imgMarginTop = dom_i.query(this).css("margin-top") == undefined ? } ����I��"&�Bip#��n�����N;���2�]�%��#�Mv��%�8�� F�Y�5?Q�Ān�!�����S��X�R+�ݶ��6��LU�ѹ�D��� if(imgMarginLeft.indexOf("px") > 0){ The lower the slope value, the flatter the terrain; the higher the slope value, the steeper the terrain. Derive a unit hydrograph ordinates and determine the runoff value for a storm of duration 1 hr. The average annual precipitation represents the amount of water available for transport in a watershed. J��!PI���']�����Nv�@J�d�7��� m-`i"�]�K[�7t �i9!2(#�iel-��x`d �@:����w��B�/���y�����z����S�✇�H$�&�`&H?6��=2F@�_ endobj endobj dom_i.query(this).css("float","none"); Instructions provided describe the steps for calculating slope using contour lines, and then finding the average, or mean, slope for an area. Watershed length is between 200 and 26,000 feet. 26 0 obj /*dom.query(document).ready(function(){ For degrees, the range of slope values is 0 to 90. S = average slope of the channel reach, m/m. How To: Calculate the average slope of an area using contour lines Summary. imgWidth = imgWidth.replace("px",""); Curve numbers (CN) are used to represent watershed characteristics that … if (imgTitle != '') { Slope measurements should be taken through a channel reach that is a minimum of 20 channel widths in length or for a distance equal to two meander wavelengths. Pools are located on the outside bends of meanders between riffles. �t�]5���b,�\&���)&Ѡ���of'�TK. } Determining the average slope of a hill using a topographic map is fairly simple. }); Select a Map Type and Subbasin, then click Submit. Get average slope and elevation on a watershed level, instead of entire surface Hi all, I am trying to get average slope and elevation data on a watershed level from a surface for catchment analysis and would like to know if there's a way to get that other than using the surface slope labels. Other Units: Change Equation Select to solve for a different unknown } It is necessary to determine velocity for this flow and compute the time of travel. Are the same a percent gradient or an angle of the watershed does exceed! ) the average slope If you are missing any of the catchment area is calculated as in.! 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