Global Journal of Engineering, Design & Technology
Open Access

Abstract

Correlation Analysis Between the Physical Catchment Descriptors (PCD’s) and the Ihacres Rainfall-runoff Model Parameters - A Case Study of Kasese District Catchments

J. Nobert & E. Busingye

This study examined the utility of the physical catchment descriptors (PCD’s) to predict model parameters so as to explore transferability of IHACRES model parameters based upon the physical catchment characteristics. The model was calibrated for four catchments to obtain a set of dynamic response characteristics (DRCs) describing the hydrological behaviour within the region. For the four catchments namely Mubuku, Rwimi, Nyamugasani and Chambura, IHACRES model was calibrated with an R 2 of 0.12, 0.25, 0.38 and 0.51 respectively. There were poor measures of fit between observed and modeled stream flow (R 2 ). This could have been due to lack of good-quality time series of rainfall data representative of the whole basin and influence of snow melt for Mubuku, Rwimi and Nyamugasani catchments. Physical catchment descriptors (PCDs) indexing topography, soil type, land cover, length of main channel, drainage density, and basin area were correlated to the hydrological model parameters. A set of DRC–PCD relationship results indicate that strongest correlations were found with the quick flow proportion (Vq), catchment storage index (1/c), catchment drying constant (TauW) and the temperature modulation factor (f) with the PCD’s. These relationships can be used to predict the model parameters in ungauged catchments to model flows. However, further work is necessary in analyzing the relationship between PCDs and model parameters using longer records of stream flows and climatic data to improve the reliability of the results