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United States Department of Agriculture

Agricultural Research Service

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Hydrograph Development
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AnnAGNPS Pollutant Loading Model

H. Green BulletHydrograph Development


Water reach routing consists of generating a hydrograph at the upstream end of the reach based upon the SCS unit graph method as described in NEH-4. Peak discharges are calculated using a procedure similar to TR-55 and a triangular hydrograph shape is substituted for the resulting non-linear shape, but the peak discharge & runoff volume are preserved. Nine rainfall distributions are included: (1) the four standard SCS Types (I, Ia, II, & IV); (b) a uniform for snowmelt & irrigation return flows; and (c) four especially developed for New Mexico. Other rainfall distributions are possible to develop at a later time.


Fred D. Theurer

Last Modified: 8/12/2016
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