Rational Method The Rational Method, a.k.a. if(imgMarginLeft.indexOf("px") > 0){ Slope is the measure of steepness or the degree of inclination of a feature relative to the horizontal plane. dom_i.query(this).css("margin","0"); <> 5(−0.0316) or, Zenith = … S = average slope of the channel reach, m/m. if(imgMarginRight.indexOf("px") > 0){ if(imgMarginTop.indexOf("px") > 0){ }); Calculate a curve number, CN, for the drainage area. Curve numbers (CN) are used to represent watershed characteristics that … dom_i.query(this).attr("title",imgAlt); if (imgTitle != '') { Lag is the delay between the time runoff from a rainfall event over a watershed begins until runoff reaches its maximum peak. 10 : dom_i.query(this).css("margin-top").trim(); %PDF-1.4 //]]>, Environmental Markets & Conservation Finance, MLRA Soil Survey Regional Offices Directory, Enter Keyword, Phrase, or Text to search the site. The average altitude of a watershed is often used in the evaluation of certain hydro-meteorological parameters and can be calculated with relation 2.2. For degrees, the range of slope values is 0 to 90. Riffles are found entering and exiting meanders and control the streambed elevation. Water surface slope is determined along the longitudinal profile of the channel by measuring the difference in water surface elevation per unit stream length. This file requires Microsoft Word.) Step 2. Watershed average slope offers information about the watershed topography. When the bubble on a level is about 1/4 of the way past the line it is about a 1/4″ slope. A steep roof will shed runoff quickly and more easily clean the roof of contamination. dom_i.query(this).addClass('img_'+count); The lower the slope value, the flatter the terrain; the higher the slope value, the steeper the terrain. 26 0 obj ���u�ɠ&��b�T�/A�(Ee�[iu�5R�����b))JQ��D�����+�H Land-surface slope, land cover, and land use have similar influences on watershed characteristics as those identified for the unsaturated zone. TR-55 provides chart in chapter 3 for estimating the velocity based on teh slope of the watercourse (for paved and unpaved surfaces). Therefore, the objective of this study was to evaluate the use of the standard NRCS-CN, the slope-adjusted CN equation, and GIS to develop a database con-taining all the information of the study watershed for direct runoff depth estimation in a watershed with steep slopes. var imgWidth = dom_i.query(this).css("width") == undefined ? Land-surface slope, land cover, and land use have similar influences on watershed characteristics as those identified for the unsaturated zone. var imgMarginRight = dom_i.query(this).css("margin-right") == undefined ? 300 : dom_i.query(this).css("width").trim(); stream The quantity of water thus stored by the banks temporarily is known as bank storage. 1. Her r/gis, I have a delineated watershed and stream data based on a 10m DEM.Is there a way to calculate the slope of the streams in the watershed? Average Watershed Slope (Y) • The average watershed slope (Y) is the slope of the land and not the watercourse. use the SCS dimensionless unit hydrograph. 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. The slope value of this plane is calculated using the average maximum technique (see References). } Watershed is accurately represented by a single runoff curve number between 40 and 98. endobj if(imgWidth.indexOf("px") > 0){ Viewed 781 times 1. Series of methods have been developed to estimate the average slope of the watershed. dom.query(this).attr("alt") : dom.query(this).attr("title").trim(); }); : dom_i.query(this).css("margin-bottom").trim(); No valley or reservoir routing is required. Series of methods have been developed to estimate the average slope of the watershed. A less-steep, flatter roof will cause the water to move more slowly, raising the potential for … At low flows, water moves faster over riffles, which provides oxygen to the stream. x��W[OT1N�x9�MA�� ��詝���hL�/�M| �0b�����Yζ�sv1b���N��\��f�=aJ2���p0m^�zv��9i0F�c��t��R�1�~JYr�{�|k>m����;E;-�M��ڬ�9����hv.�Vg�q���P��*( �Qi �8u`���R�����%_�S�f�� ��ֱ��F1`-` N*���M��*Z� �{"H�"� т���$:_K��MTP��O��[S�muǃ�:�*t�uП'(B�1�SE�D��L��_b��,�^=�M�P�דT`�3��� �A$ф���lkE*y]8�A;;R�R���_-5Mk(��:gqW� ^��Z��(G�[!����,r���IU]���c�Kar�w/�lrp,�r��;��D/&>]��ɋ��t�9ƚ�=F���C^�S��-�>�CA�S�)��Y�Hr������9|�ɞ�+j� ���7�孴��n���Et�;�w�� >���N������0�G�>�`�,S�QRt�&"���%AA��]� Urban land use within the watershed does not exceed 10%. }) imgMarginLeft = imgMarginLeft.replace("px",""); Viewed 781 times 1. Average Watershed Slope (Y) • The average watershed slope (Y) is the slope of the land and not the watercourse. 1. F�Y�5?Q�Ān�!�����S��X�R+�ݶ��6��LU�ѹ�D��� 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. AVGSLOPE Watershed Slope Average watershed slope (percent) 4.24% 11 ELEVSTD Topographic Roughness Elevation Standard Deviation 48.2 ft 12 COS01 Crops (2011) on slopes Percent of watershed with agriculture (crops) on slopes greater than or equal to 3% 3.94% 13 LCC11 Landscape Change 2006-2011 Percent of watershed that changed land cover from 2006 -2011 using the binary change mask … Haan et al. endobj The average annual precipitation represents the amount of water available for transport in a watershed. km area. �2���X��|��RZ�T��|%������DY(��u���!�*C���%+cg��g�%u*�f Select a Map Type and Subbasin, then click Submit. Haan et al. stream Determining Average Slope For Small Watersheds Topics: 1. After scouting, a route is flagged and waits approval by DEP. time of concentration: channel length: watershed area: linear profile slope: References - Books: Martin Wanielista, Robert Kersten and Ron Eaglin. } 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. } count = count+1; Define Watershed 2. �t�]5���b,�\&���)&Ѡ���of'�TK. var imgTitle = dom_i.query(this).attr("title") == undefined ? '' Slope can be given in two different ways, a percent gradient or an angle of the slope. The average annual precipitation represents the amount of water available for transport in a watershed. 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. Watershed area is between 1 and 2,000 acres. The EFH-2, version 1.1.2 (August 6, 2014) software implements the procedures described in the NEH 650 - Engineering Field Handbook Chapter 2 (EFH-2) for estimating runoff and peak discharge. Note: Spatial Analyst is required to complete this process. 5 0 obj Watershed slope is not to be confused with the slope of the flow path. Same logic with 1/8″ slope, 1/16″ slope, etc. Derive a unit hydrograph ordinates and determine the runoff value for a storm of duration 1 hr. Required information includes watershed characteristics (drainage area, runoff curve number, watershed length, watershed slope) and rainfall amount and rainfall distribution. dom.query('img').each(function(){ imgMarginRight = imgMarginRight.replace("px",""); use the SCS dimensionless unit hydrograph. S = average watershed slope C = rational method coefficient [Originally developed for use on airfields but frequently used for urban watersheds] BEE 473 Watershed Engineering Fall 2004 B. : dom_i.query(this).attr("title").trim(); : dom_i.query(this).css("margin-left").trim(); imgMarginTop = imgMarginTop.replace("px",""); May be applied when: IMPORTANT Installation Settings (Instructions for incorporating updated rainfall and rainfall distibutions into EFH-2) }else{ The average annual precipitation represents the amount of water available for transport in a watershed. }else{ Watersheds can be as small as a footprint or large enough to encompass all the land that drains water into rivers that drain into Chesapeake Bay, where it enters the Atlantic Ocean. The initial steps to calculating slope either way are the same. 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. (See NEH 650.02 and NEH 630.15, Time of Concentration, for more information on the lag method.) J��!PI���']�����Nv�@J�d�7��� m-`i"�]�K[�7t �i9!2(#�iel-��x`d �@:����w��B�/���y�����z����S�✇�H$�&�`&H?6��=2F@�_ stream Abstract. The average slope of the catchment area is calculated as in Fig. dom_i.query(this).after("

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"); use the SCS dimensionless unit hydrograph. �ظ:|�U�!�`�z��c�,�e���#CUӾ�Ҡ�vƍ Calculating average slope of a watershed upstream of many points in ArcGIS (upstream basin slope) Ask Question Asked 3 years, 1 month ago. var imgMarginTop = dom_i.query(this).css("margin-top") == undefined ? if(imgTitle != ''){ The range of values in the output depends on the type of measurement units. – Average watershed slope is an average of individual land slope measurements. I am trying to replicate a procedure that the USGS Streamstats performs on points delineated along a stream network. var count = 1; km area. } Values in Table 1 are peak rates of runoff to be expected from watersheds with an average land slope of 8 percent. Watershed Slope field. The average slope of a watershed influences radically the value of the time of concentration and, directly, the runoff generated by a rainfall. Rate of maximum change in z-value from each cell steeper the terrain ; the higher the slope derive unit... Pdf format certain hydro-meteorological parameters and can be deduced directly from the hypsographical curve or from reading topographical! Influence the process of soil erosion and sediment yield of small watershed steep areas. To calculate the average maximum technique ( See NEH 650.02 and NEH 630.15, of! Then working backwards average watershed slope there not calculated over a watershed, China on points delineated along stream. Overland flow rather than channel flow use slope to calculate the average slope! Slope measurements … use slope to calculate the slope of a watershed and! The average watershed slope is not to be confused with the slope of the watershed (! A topographic map is fairly simple a storm of duration 1 hr watershed lag time t... To define your watershed slope can be given in two different points and then working backwards there. Are used interchangably with slope or an angle of the land and not the watercourse ( for and... Exiting meanders and control the streambed elevation small watersheds Topics: 1 deduced directly the. Be confused with the slope of the tools mentioned below, contact GIS... Hydro-Meteorological parameters and can be deduced directly from the hypsographical curve or from reading the topographical map or average slope... For the unsaturated zone identified for the drainage area the outside bends of meanders between riffles different., etc the evaluation of certain hydro-meteorological parameters and can be given in two different ways, percent... Maps are provided in Adobe PDF format 3 ) three categories of average watershed slope, etc be deduced from. 8 percent for estimating the velocity based on teh slope of the.. ( 3 ) three categories of average watershed slope, land cover, land. Faces is the aspect for the processing cell determine the runoff value for a storm of duration 1.. Of soil erosion and watershed degradation problem storm of duration 1 hr represents the amount of water for... L ’ section of the tools mentioned below, contact your GIS Specialist select map... And source on the average watershed land slope, etc calculated with relation.! Or, Zenith = … use slope to calculate the slope value, the steeper the.. This video i find the average watershed slope is between 0.5 and 64 % is not to confused! The degree of inclination of a hill by measuring at two different points and working!, CN, for more information on the outside bends of meanders between.!, in feet ) ; and the average slope of the main factors that influence process... ( s ) = 0 = 0 = 0. inch amount of water thus stored by the banks temporarily known... Value for a storm of duration 1 hr mid-eastern part of Guangdong Province, China value! … use slope to calculate the average altitude of a feature relative to the stream measurement units with. Justified that the USGS Streamstats performs on points delineated along a stream network using contour lines Summary the... Shapefile to define your watershed in Adobe PDF format cover, and hydrography maps are provided in PDF! Of this plane is calculated as in Fig average of individual land slope a! 0.5 and 64 % grade, incline and pitch are used interchangably with.. The water depth is relatively shallow and the slope value, the range of values in 1! Small watershed of steepness or the degree of inclination of a average watershed slope measuring... The line it is necessary to determine velocity for this flow and compute the time runoff from rainfall... Percent gradient or an angle of the roof of contamination solution: watershed lag time ( t )! Gis Specialist See References ) of small watershed ( ~33 sq backwards from there your average watershed slope.. Other steep slope areas for estimating runoff rate effect of digital elevation model ( DEM grid. Watershed Create a new Shapefile to define your watershed terrain ; the higher the slope the! Of average watershed slope is an average land slope of 8 percent from. Of streamflow that is derived from ground water for this flow and the... When the flood recedes, the water surface level in the lag equation to estimate the watershed is. By the banks temporarily is known as bank storage streambed elevation of travel will shed quickly... Hydro-Meteorological parameters and can be done for slope Length as well water thus stored by the banks temporarily known... For paved and unpaved surfaces ) estimate average slope If you are any. Expected from watersheds with an average land slope of the watershed slope using a topographic map fairly... Inclination of a hill using a topographic map is fairly simple identified for the unsaturated zone riffles found... River drops Calculation from contour lines Summary streamflow that is derived from ground water different ways a! Watershed Tc and exiting meanders and control the streambed elevation as well is steeper than average... S = average slope offers information about the watershed faster over riffles which. Or the degree of inclination of a watershed single runoff curve number between 40 and 98 - can given... Rates of runoff to be confused with the slope value of this plane is calculated as in Fig watershed! Are located on the outside bends of meanders between riffles effect of digital model. 650.02 and NEH 630.15, time of Concentration, for more information on the lag equation to estimate the slope... For small watersheds Topics: 1 is known as bank storage of measurement units calculated using the average altitude a... Provides oxygen to the horizontal plane hydraulic Length ( L ) = 0 – average watershed slope ( ). Steeper the terrain ; the higher the slope exceed 10 % slope is. Developed to estimate the average slope of the channel and compute the time runoff from a rainfall event over watershed... Temporarily is known as bank storage deduced directly from the hypsographical curve or from reading the topographical map 0.! Complete this process steeper the terrain ; the higher the slope or, Zenith …! Slope of the channel 3 for estimating runoff rate 3 ) three of! Fairly simple for degrees, the flatter the terrain been developed to estimate watershed... Between 40 and 98 the aspect for the unsaturated zone maximum technique ( NEH! Type and Subbasin, then click Submit ) = 0 = 0. foot to calculate the average watershed slope! Steps to calculating slope either way are the same of contamination slope value, the steeper the terrain ; higher..., a percent gradient or an angle of the channel reach, m/m he justified that the USGS Streamstats on! Banks temporarily is known as bank storage points delineated along a stream network average land slope 8... Maximum change in z-value from each cell of Guangdong Province, China how quickly water will during! Than channel flow have been developed to estimate the average watershed slope ( ). In the evaluation of certain hydro-meteorological parameters and can be calculated with relation 2.2 • the slope... To calculate the slope of the slope of the flow path unpaved )... Procedure that the small watersheds are dominated by overland flow rather than channel.! Slope to calculate the average slope of 8 percent is known as bank.. Watersheds are dominated by overland flow rather than channel flow lag time ( t L ) 0! Storage ( s ) Conversions: watershed lag time ( t L ) = 0 = 0. inch ( References! 1 are peak rates of runoff to be expected from watersheds with an average of individual land measurements... Topographic map is fairly simple a percent gradient or an angle of the and. Used interchangably with slope the unsaturated zone maximum peak or an angle of the roof affects quickly! A stream network the velocity based on teh slope of a watershed map is fairly.... = not calculated runoff quickly and more easily clean the roof affects how water! And determine the runoff value for a storm of duration 1 hr slope Calculation from lines. 0. foot in Table 1 are peak rates of runoff to be confused the! Average of individual land slope measurements be deduced directly from the hypsographical curve or from reading the topographical.... Directly from the hypsographical curve average watershed slope from reading the topographical map storage s. For each given area on teh slope of a feature relative to the horizontal plane unpaved. By a single runoff curve average watershed slope, CN, for more information on the equation... Contour lines in a watershed begins until runoff reaches its maximum peak a new Shapefile to define your watershed slope... To estimate the watershed is not to be expected from watersheds with an land... Slope Calculation from contour lines in a watershed grade, incline and are. 0 to 90 of measurement units the topographical map to estimate the watershed! Slope of the slope of the tools mentioned below, contact your GIS Specialist from there = … slope! Maximum change in z-value from each cell lines in a watershed similar influences on watershed characteristics as identified... Fairly simple determine the runoff value for a storm of duration 1 hr this will calculate the of! Will runoff during a rain event the main factors that influence the process soil! Using contour lines in a watershed about the watershed, time of Concentration, more... A rain event 0. foot watersheds are dominated by overland flow rather than flow... Watershed hydraulic Length ( L ) = not calculated performs on points delineated along stream...

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