Shortage of water may be the most crucial environmental problem facing Israel today, touching upon its very existence. Water scarcity is exacerbated by the deteriorating quality of water resources due to demographic, industrial and agricultural pressures. Since the mid-1970s, demand has at times outstripped supply.
Climate, Geography and Hydrology
Israel’s water sources are limited by the country’s climate, geography and hydrology. Seventy-five percent of the annual rainfall is concentrated into four winter months, with at least six rainless months. Rainfall averages 1,000 millimeters per year in some parts of Galilee in the north in contrast to 25 millimeters in the southern Negev. Even greater variations occur from year to year, with periods of drought or near-drought interspersed with periods of heavy rainfall. The total mean annual precipitation over the catchment areas feeding Israel’s various water sources amounts to 10,000 million cubic meters (MCM); of this, only 18% is utilizable, with the rest lost to the atmosphere or to the Mediterranean and Dead Seas. Global climate change may further magnify the pressure on Israel’s water system by increasing temperatures and evaporation rates and changing the precipitation regime for better or worse. Finally, while water demand is greatest in the heavily populated coastal regions and in the southern half of the country, rainfall, water storage reservoirs and water resources are largely concentrated in the north.
These climatic, geographic and hydrologic constraints necessitate a water management policy which is based on the maintenance of a long-term reserve for water regulation and use, the ability to cut allocations for water use in drought years, and the development and use of unconventional water sources.