Stanhill, G., Inst of Soils & Water, Agric Res Organization, Bet Dagan, Israel
Rapaport, C., Inst of Soils & Water, Agric Res Organization, Bet Dagan, Israel

The total annual volume during 1931-1984 averaged 7.92 km2, with annual values normally and randomly distributed. Interannual variation of the integrated totals - 24.4% - was three-quarters of the value derived from measurements at individual stations with comparable rainfall. Two-thirds of the interannual variation was filtered by a 5-yr running mean showing two long and relatively constant wetter than average spells between 1934 and 1954 and between 1965 and 1981, separated by a shorter but more pronounced dry spell from 1955 to 1964. There was no evidence for any significant cyclic or long-term trends in, or effects of cloud seeding on the total annual volume of rain. The spatial distribution of annual rainfall was continuous, asymmetrical and persistant; two-thirds of the total volume fell on the approximately one-third of the total area between the 300 and 800 mm isohyets. -from Authors