Calculating specific catchment area

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Abstract

[1] Specific catchment area, defined as the area of land upslope of a width of contour, divided by the contour width, is a commonly used quantity in hydrology to describe complex terrain for analyzing water flow on hill slopes; it can be a surrogate for water discharge per unit flow width. Although specific catchment area is important in hydrological, ecological, and geological studies, it can be difficult to estimate. Gallant and Hutchinson provide a simple differential equation that describes the rate of change of specific catchment area along a flow path. The equation can be directly integrated to calculate specific catchment area at any point on a digital elevation model. The method avoids use of catchment area and width estimates, which have errors. Although the method is more computationally intense than most methods for calculating specific catchment area, it can be used as a reference against which other methods can be tested. (Water Resources Research, doi:10.1029/2009WR008540, 2011)