Assessment of the impact of a parameter estimation method for the Nash Model on selected parameters of a catchment discharge hydrograph

Cracow University of Technology, Institute of Water Engineering and Water Management, 24 Warszawska Str 31-155 Cracow, Poland

^* Corresponding author: katarzyna.kolodziejczyk@iiw.pk.edu.pl

Abstract

An analysis of the usefulness of two parameter calculation methods (N and k parameters) for the Nash Model was performed to transform effective rainfall into discharge based on two rainfall episodes gauged at the Kostrze gauging station as well as urban development data for the city of Cracow for 2014 and data obtained from a soil and agriculture map. The methods were the Rao et al. method and the Bajkiewicz-Grabowska method for regression relationships between instantaneous unit hydrograph model parameters and the physiographic parameters of a catchment. Effective rainfall was calculated for each rainfall episode using the SCS-CN method. A direct discharge hydrograph was calculated based on an effective rainfall hyetograph and using the Nash Model. Research has found that both studied methods yield comparable results, which indicates that both methods of effective rainfall transformation into discharge are useful. In addition, it has been shown that the impact of the Nash Model parameter estimation method on discharge hydrographs is minimal.