The total catchment area of the lake is about 51,876 Km2 which is 3.15 % of that of the entire country, and includes 7 % of the total surface water in Iran .
There are thirteen main rivers in the lake basin, among them Zarrineh
rood, the largest with a total annual discharge value of about 2×109 m3 [12,17]. Climate in the Urmia Lake basin is harsh and continental, affected mainly by the mountains surrounding the lake [12,1].
Considerable seasonal fluctuations in air temperature occur in this
semi arid climate with an annual average precipitation of between 200
and 300 mm [18,25].
The air temperature usually ranges between 0 and -20°C in winter, and up to 40°C in summer . From this point of view, Urmia Lake is a critical asset for the region, because it acts to moderate these extremes . Annual inflow into the lake is 6900×106 m3, of which 4900×106 m3 is from rivers, 500×106 m3 from flood water (through rainfall) and 1500×106 m3 from precipitation [7,26]. Underground springs are also a source of water, but the volume is not known .