Impact of flood wave characteristics and catchments on the parameters of the synthetic unit hydrographs - beta and Weibull distribution

key words: unit hydrographs, synthetic unit hydrograph - Weibull and beta distri-bution

Summary:

The article evaluated the possibility of description of the observed unit hy-drographs using the synthetic unit hydrographs defined by beta and Weibull prob-ability distributions in the following sections: Gorliczyna on the Mleczka river, Iskrzynia on the Morwawa river, Jasło on the Jasiołka river and Brzeźnica on the Wielopolka river. The performed analysis was based on the observed hydrographs from the multi-year period of 1980-82 from the summer and winter half-years. The analysis itself was based on the unit hydrographs describing the direct outflow from the catchment. The shape and scale parameters of both analyzed distributions were defined using a function that based on minimization of the difference between the observed and simulated flow during the culmination of the analyzed episode. The correctness of the unit waves description by the analyzed distributions was tested using the Nash and Sutcliffe efficiency coefficient. The analysis indicated that the analyzed unit hydrographs are well described by the beta and Weibull distribution (slightly better results of calculations were obtained for the beta distribution). The quality of the models was unsatisfactory only for 27% of all analyzed episodes. For both functions the relationship observed between flow values in the culmination and the β scale parameters was the strongest.

 

 

Citation:

Wałęga A. 2011. Impact of flood wave characteristics and catchments on the parameters of the synthetic unit hydrographs - beta and Weibull distribution. Infrastruktura i Ekologia Terenów Wiejskich. Nr 2011/ 07