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Processing a Delineated Watershed to Include Green & Ampt Soil ParametersBy Jerome Richard Perales and David Maidment ABSTRACT There are several models used to calculate abstraction due to infiltration
including the SCS method and the initial loss plus constant loss rate
model. However, these models have limitations. The SCS Curve Numbers
relating abstractions to soil types and land use have been arbitrarily
determined, and the initial loss plus constant loss rate model is a
non-physical model calibrated with gauged data. A more advantageous
method to determine abstractions is to relate loss rates to physical
characteristics of the watershed in a continuous simulation so that
loss rates may be computed as a function of soil moisture conditions
at the beginning of a storm (Reed and Maidment 1998). The Green & Ampt
Infiltration Model is a physical model which relates the rate of infiltration
to measurable soil properties such as the porosity, hydraulic conductivity,
and the moisture content of a particular soil. With the use of the State
Soil Geographic Database (STATSGO) and a subprogram that has been developed
using Geographical Information Systems (GIS) in the ArcView environment,
it is possible to assign Green and Ampt parameters to a watershed of
interest. Furthermore, this database allows for a general soil analysis
of a given area including percentages of the various soil textures. The highlighted links that follow are connected to Adobe pdf files of the corresponding material. To view them you must have the Adobe Acrobat Reader 3.0. View the Report...(2.1MB)
These materials may be used for study, research, and education, but please credit the authors and the Center for Research in Water Resources, The University of Texas at Austin. All commercial rights reserved. Copyright 2000 Center for Research in Water Resources. |
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