The best relationship between lumped hydrograph parameters and urbanized factors

Abstract

This study mainly explores the best relationship between hydrograph parameters and urbanized factors in urbanized areas. Urbanization of a developing watershed is analyzed through 51 available rainfall-runoff simulations from 1966 to 2002. Forty of these rainfall-runoff events were calibrated to determine the relationships between impervious area and urbanized factors. During the calibration process, the block Kriging method was used to estimate the mean rainfall, and its hourly excesses were calculated by nonlinear programming. Then, clear tendencies between parameters and urbanized factors were produced by comparing the results of the annual average and optimal interval methods. The remaining eleven cases were used to verify the established relationships. The calibration and verification results confirm that the integral approaches used in this study can effectively illustrate the hydrological and geomorphic conditions in complex urbanized processes. Parameter n responds more sensitively than parameter k to increasing impervious area and population density. Additionally, parameter n responds more strongly to imperviousness than to population. Therefore, this study demonstrates that an impervious area is the main consequence of ongoing urbanization in the Wu-Tu watershed. The satisfactory results show that kernel response of the watershed would be more sharp-pointed and be shifted forward in peak due to an increased impervious cover.