 Forest cover is sparse, especially in the Kura and Aras headwaters, and most of the water that falls on the highlands becomes runoff instead of supplying groundwater.Attempts at flood control include the constructions of levees, dikes and dams, the largest of which is at Mingachevir, an -high rockfill dam impounding over of water.However, because of the high sediment content of rivers in the Kura basin, the effectiveness of these floodworks is limited and decreases every year.