INFLUENCE OF RAINFALL OBSERVATION NETWORK ON MODELED HYDROLOGICAL RESPONSE

Abstract

Precipitation data, one of the most important input required in hydrological modeling and forecasting, are usually recorded using raingauges which are classical and fundamental tools able to provide an estimate of rainfall at a point. The consistency of precipitation monitoring network in terms of spatial scale (network density and location of raingauges) and time resolution has to be capable to reproduce, with acceptable accuracy, the characteristics of the flood phenomenon. In this context, over the last thirty years, several studies concerning the influence of point measurement of rainfall for the estimation of total runoff volume have been carried out. Aim of this paper is using a physically based and distributed-parameter hydrologic model in order to investigate the influence of the raingauges network configuration, in terms of number and spatial distribution, on the estimation of hydrograph peak discharge considering also the spatial distribution of soil types in the basin. The hydrologic model has been applied to the catchment of Baron Fork located in Oklahoma. The radar measurements, available in the area, have been assumed as representative of the “real” distribution of precipitation. Its hydrological response is compared with that obtained from interpolated precipitation fields, which, in turn, are obtained by varying the distribution of the raingauges network. The analysis has been first carried out assuming a simplified spatial distribution of soil characteristics and then considering the real spatial distribution of soil types.