The purpose of this paper is to show how accurate radar-estimated rainfall, with good temporal and spatial resolution, can be used for hydrological purposes. A recent methodological advance in rainfall measurement using conventional weather radars has made it possible to account for much of the variation between the precipitation radar echo intensity and rain intensity. A method known as the window probability matching method (WPMM) was applied to radar measurements over several catchment areas in central Israel. Comparison of daily raingauge measurements with radar rainfall estimates demonstrated good agreement. The standard error of radar-estimated rainfall was only 7% for a storm with a total average accumulation of 328 mm. Several case studies are provided which demonstrate the advantage of having an accurate rain field for calculating excess rainfall for each of the area grid squares in the watershed. Storm excess rainfall for different time durations depends strongly not only on the area size, but also on the differences in the rainfall intensity sequences. Accurate radar rain fields can permit dynamic calculations to be made along the storm path.
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