Peak unit discharge estimation based on ungauged watershed parameters

Abstract

In this study, a methodology has been proposed that can be used to estimate the peak unit discharge for all the watersheds in the northern part of Cyprus. Thus, the Soil Conservation Service method was used to determine the unit hydrographs of 366 watersheds available in the study area. Through the Digital Elevation Model with a spatial resolution of 12 m the watershed characteristics such as watershed boundaries, area, slope, and streams were defined. Runoff curve number maps for each watershed were created by the integration of the land use/land cover and soil data within a Geographic Information System technique. In the end, through genetic algorithm optimization, a dimensionally homogenous formula as a function of basin parameters was developed. The developed function can be used to estimate the unit discharge at ungauged watersheds of the northern part of Cyprus with a high degree of accuracy. Furthermore, an empirical equation based on morphometric watershed characteristics was also formulized to replace the time of concentration with parameters that directly affect the time, such as Bifurcation ratio and drainage density. The proposed empirical equation estimates the unit discharge in all the watersheds with the mean relative error of 11.97%.