SPECIFIC DEGRADATION OF WATERSHEDS

Boubacar KANE' and Pierre Y. JULIEN'

ABSTRACT

An extensive database of reservoir sedimentation surveys throughout continental United States is
compiled and analyzed Lo determine specific degradation SD relationships as function oFtnean annual
rainfall R, drainage area A, and watershed slope S. The database contains 1463 field measurements
and specific degradation relationships are defined as function of A, R and S. Weak trends and
significant variability in the data are noticeable. Specific degradation measurements are log normally
distributed with respect to Q A, and S and 95% confidence intervals are determined accordingly. The
accuracy of tile predictions does not significantly increase as more independent variables are added to
the regression analyses.

Key Words: Specific degradation, Sediment yield, Resewoir sedimentation

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