Curve numbers (CN) are used to represent watershed characteristics that … 1997. Water surface slope is determined along the longitudinal profile of the channel by measuring the difference in water surface elevation per unit stream length. F�Y�5?Q�Ān�!�����S��X�R+�ݶ��6��LU�ѹ�D��� (3) three categories of average watershed slopes. Average watershed slope is between 0.5 and 64%. The average slope of the catchment area is calculated as in Fig. Active 3 years, 1 month ago. 2.4. Wuhua county is located at the mid-eastern part of Guangdong Province, China. The lower the slope value, the flatter the terrain; the higher the slope value, the steeper the terrain. Series of methods have been developed to estimate the average slope of the watershed. Haan et al. Rational Method The Rational Method, a.k.a. A watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel. "none" : dom_i.query(this).css("float").trim(); if(imgMarginLeft.indexOf("px") > 0){ x��W]kT1}��"�/�-�jIJo�L�_Eė�Z�*V��T����ݽ7��ܮk)��Ædf�̜���%S����/����c��6� �(ct���;N+�.�\�b��^4_��[sIᝢ��&,�6�u�����Ѫ�(��4.L��=Z��5* �0NE����N�S����+�\��٫Y�f�T��>7�k) �RSc0�@'���-H��?HK��H�MԦ��$�Z���S����H��q�����%2�X�b�i������"��=%Fg'�� L .��rA�T�K� )x��Ѣԑҹ�����|/���� �ظ:|�U�!�`�z��c�,�e���#CUӾ�Ҡ�vƍ }else{ var count = 1; In this video I find the average slope of a hill by measuring at two different points and then working backwards from there. (1982) mentioned that, the above relationship does not give accurate value of time of concentration for the watersheds less than 5 sq. var imgMarginRight = dom_i.query(this).css("margin-right") == undefined ? If the average land slope on a watershed differs from this, multiply the value from Table 1 by the following factor: Average land slope Topographic factor (T) 0.5 percent: 0.50: 1 percent: 0.65: 2 percent: 0.72: 3 percent: 0.78: dom_i.query(this).css("float","none"); Land-surface slope, land cover, and land use have similar influences on watershed characteristics as those identified for the unsaturated zone. Lag is the delay between the time runoff from a rainfall event over a watershed begins until runoff reaches its maximum peak. Draw the ‘L’ section of the main stream. if(imgMarginTop.indexOf("px") > 0){ // 0){ use the SCS dimensionless unit hydrograph. Physiographic Characteristics Slope: It controls the rainfall distribution and movement, land utilization and watershed behavior. Shallow Concentrated Flow After about 300 feet, the water flow starts to concentrate, (e.g., flow in small grass swales) and can no longer be computed using sheet flow formulas. ���u�ɠ&��b�T�/A�(Ee�[iu�5R�����b))JQ��D�����+�H The average slope of a watershed influences radically the value of the time of concentration and, directly, the runoff generated by a rainfall. The topographic feature is one of the main factors that influence the process of soil erosion and sediment yield of small watershed . 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. 5(−0.0316) or, Zenith = … (See NEH 650.02 and NEH 630.15, Time of Concentration, for more information on the lag method.) The average slope of the catchment area is calculated as in Fig. 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. Riffles are found entering and exiting meanders and control the streambed elevation. }else{ stream } 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 … //dom_i.query(imgDiv).append(""); When the flood recedes, the water surface level in the river drops. 562 10 : dom_i.query(this).css("margin-right").trim(); var imgFloat = dom_i.query(this).css("float") == undefined ? 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. The average annual precipitation represents the amount of water available for transport in a watershed. Same logic with 1/8″ slope, 1/16″ slope, etc. Watershed area is between 1 and 2,000 acres. dom_i.query('.img_'+count).wrapAll("
"); potential watershed storage (S) = 0 = 0. inch . time of concentration: channel length: watershed area: linear profile slope: References - Books: Martin Wanielista, Robert Kersten and Ron Eaglin. })*/ The same can be done for Slope Length as well. / EFH2 Estimating Runoff Volume and Peak Discharge. Active 3 years, 1 month ago. Clip Contour Lines 3. Factors selected for rating the watershed characteristics upstream from surface-water intakes are average annual precipitation, land-surface slope, land cover, land use, and ground-water contribution. I am trying to replicate a procedure that the USGS Streamstats performs on points delineated along a stream network. use the SCS dimensionless unit hydrograph. Table 3-1 contains CN values for different land Begin by Opening a MapBook Project in ArcMap. Watershed length is between 200 and 26,000 feet. } 300 : dom_i.query(this).css("width").trim(); After scouting, a route is flagged and waits approval by DEP. 10 : dom_i.query(this).css("margin-top").trim(); Watershed length is between 200 and 26,000 feet. endobj 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. Watershed lag time equation calculator solving for average watershed slope given watershed lag time, watershed hydraulic length and potential watershed storage Watershed Subbasin Maps This web page provides access to five pre-built map series for each of Montana’s subbasins (8-digit HUC level). } 16 0 obj The use of a z-factor is essential for correct slope calculations when the surface z units are expressed in units different from the ground x,y units. Between riffles watersheds Topics: 1 land cover, and land use within the watershed Tc as in Fig and... 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