ANALYSIS OF HYDROLOGCAL CYCLE IN AN URBAN BASIN IN THE TAMA HILLS CONSIDEREING INFILTRATION VARIATION IN UPPER SOIL LAYER

Abstract

Infiltration models are used to estimate the effective rainfall for runoff analysis, and its role is important for the accurate simulation of a runoff hydrograph. Only a few infiltration models take rainfall intensities into account. The infiltration model proposed recently by Diskin and Nazimov (1995) takes into consideration the rainfall intensity variations, and it can also be used to calculate the variation of the infiltration capacity for un steady rainfall. This infiltration model is a fairly simple conceptual model. In this paper, the Diskin-Nazimov infiltration model is applied to the actual runoff analysis, and validates the runoff model's applicability. Concretely, the lumped hourly hydrological model presented by Ando et al.(1981) is coupled with the Diskin-Nazimov infiltration model to calculate the effective rainfall. The study basin is the Kotta River basin which is located in Tama New Town, an urban development in the Tama hills, in the western suburbs of Tokyo. The results showed that the calculated hydrographs represent the observed hydrographs for long-term rainfall runoff events in the Kotta River basin.