United States Department of Agriculture
Natural Resources Conservation Service
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Hydraulics and Hydrology
Tools and Models - EFH2

A program for determining peak discharge as prescribed by Engineering Field Handbook Chapter 2.
Required information includes watershed characteristics (drainage area, curve number, hydraulic length, watershed slope) and rainfall amount and distribution. 

This program has restricted applications.  May be applied when: 

  • Watershed is accurately represented by a single runoff curve number between 40 and 98.
  • Watershed area is between 1 and 2,000 acres.
  • Watershed hydraulic length is between 200 and 26,000 feet.
  • Average watershed slope is between 0.5 and 64%.
  • No valley or reservoir routing is required.
  • Urban land use within the watershed does not exceed 10%.

Zip File Download program here (8.2mb)

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