Testing trends in annual maximum discharge series in Israel

Abstract

A variety of statistical tests were carried out on 64 annual maximum discharge series observed in Israel during the last six decades. The period of observation at each of the stations selected is at least 25 years, with an average of 42 years per station. The tests aimed at detecting trends in the central values of the discharges, as well as in their variation. Except for one region, the detected changes are of local extent, if any. A decline in the annual maximum discharges and in their variability is found for the Upper Jordan River and its tributaries. A general rise in the variability is found over most other regions. These appear to result from changes in the meteorological causes of high discharges. Few high discharges occurred in the 1970s and in the early 1980s, whilst many occurred in the 1990s.