Agriculture, diversions, and drought shrinking Galilee Sea

Abstract

In water-limited regions worldwide, climate change and population growth threaten to desiccate lakes. As these lakes disappear, water managers have often implicated climate change-induced decreases in precipitation and higher temperature-driven evaporative demand—factors out of their control, while simultaneously constructing dams and drilling new wells into aquifers to permit agricultural expansion. One such shrinking lake is the Sea of Galilee (Lake Kinneret), whose decadal mean level has reached a record low, which has sparked heated debate regarding the causes of this shrinkage. However, the relative importance of climatic change, agricultural consumption, and increases in Lebanese water consumption, remain unknown. Here we show that the level of the Sea of Galilee would be stable, even in the face of decreasing precipitation in the Golan Heights. Climatic factors alone are inadequate to explain the record shrinkage of the Sea of Galilee. We found no decreasing trends in inflow from the headwaters of the Upper Jordan River located primarily in Lebanon. Rather, the decrease in discharge of the Upper Jordan River corresponded to a period of expanding irrigated agriculture, doubling of groundwater pumping rates within the basin, and increasing of the area of standing and impounded waters. While rising temperatures in the basin are statistically significant and may increase evapotranspiration, these temperature changes are too small to explain the magnitude of observed streamflow decreases. The results demonstrate that restoring the level of the Sea of Galilee will require reductions in groundwater pumping, surface water diversions, and water consumption by irrigated agriculture.