5th International Conference on Rain Water Cistern Systems
"Rainwater Catchment for Future Generations"
Keelung, Taiwan, R.O.C. - August 1991

Section 4: Hydrological Data and Analysis

Page 190

Test Of Watershed Acidification Models Responses To Rainfall Intensity

Fi-John Chang
Department of Agricultural Engineering, National Taiwan University

Abstract

Mathematical models are useful in improving our understand- ing of various processes and predicting the response in freshwater chemistry to changes in the deposition. A general weakness in models of the effects of acid deposition is that the models have not been tested sufficiently against observation. An alternative way to assess the applicability of models is to perform hypothesis test. Consequently, a hypothsis--increasing rainfall intensity will increase outflow hydrogen concentration--was tested with two well known watershed acidification models, the ILWAS and Birkenes models.

The ILWAS models confirms the hypothesis, while the Birkenes model does not produce the same conclusion. This is probably due to the simplicity of the hydrologic submodel of the Birkenes model and its assumption of constancy of the cation exchange capacity. The result of test the ILWAS model for the hypothsis show that it is a useful tool in the investigation of watershed acidification. This process-oriented model provides the essential insight to make predictive assessment of the effect of surface and subsurface water acidification under different loading.

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