MODELING SURFACE RUNOFF - A CASE-STUDY OF A CULTIVATED FIELD IN SOUTHERN FINLAND

The objective of this study was to compare approaches to modeling surf ace runoff due to summer and autumn storms on a cultivated field. The data consisted of measurements performed every 15 minutes during rainf all-surface runoff events in 1993. A transfer function model was formu lated using measured rainfall or rainfall excess as an input and surfa ce runoff as an output. The physical models were based on the kinemati c wave approximation of the Saint Venant equations. Surface runoff was assumed to flow first as an overland flow on a level field and second in rills. The results showed that the transfer function model using r ainfall excess as an input, and the implicitly solved rill flow model performed the best with respect to the fitness coefficients, which den oted the efficiency of the model. The testing of the models using fixe d parameter combinations indicated that an event based parameter estim ation was not applicable in verifying the models to changing condition s.