urb_wash

Wash-off coefficient for removal of constituents from impervious surfaces

Wash off is the process of erosion or solution of constituents from an impervious surface during a runoff event. The original default value for urb_wash was calculated as 0.18 mm-1 by assuming that 13 mm of total runoff in one hour would wash off 90% of the initial surface load (Huber and Heaney, 1982). Using sediment transport theory, Sonnen (1980) estimated values for the wash-off coefficient ranging from 0.002-0.26 mm-1. Huber and Dickinson (1988) noted that values between 0.039 and 0.390 mm-1 for the wash-off coefficient give sediment concentrations in the range of most observed values. This variable is used to calibrate the model to observed data.

References

Huber and Dickinson (1988)

Huber and Heaney (1982)

Sonnen (1980)