A physically-related regional model for extreme discharges in Israel

Abstract

Israel is a small country which experiences wide variations in magnitudes of extreme discharges. A consistent model has been constructed for prediction of such discharges throughout the country. Extreme flow characteristics, geographical proximity, lithology, soils, and rainfall properties are the major factors in the delineation of relatively homogeneous regions within the country. For each region, discharge-area relationships are formulated in association with low exceedance probabilities. These relationships follow at-site predictions which have been prepared by fitting the log Pearson type III distribution to annual maxima series of peak discharges. For catchments larger than 100 km 2 in area, the differences between the regional and the at-site predictions are small. Relatively high extreme discharges are found for the arid area where rainfall depth is low, for an area of steep slopes, for areas of low permeable lithology and soils, and for areas where the fraction of intense rainfall in the total depth of precipitation is high. For large arid catchments, the discharge- area relationships exhibit a negative trend. The model is simply applicable and appears suitable for other semiarid and arid areas. © 1997 Taylor & Francis Group, LLC.