Environmental Flow Contributions from In-Basin Rivers and Dams for Saving Urmia Lake

Abstract

Dramatic shrinkage of the internationally registered Urmia Lake, Iran, is mainly related to the reduction in rivers flowing into the lake. This flow reduction is due to irrigation of agricultural lands upstream of the lake. The potential flows into the lake are greatly influenced by ten perennial rivers, hosting 24 large dams. Among these is the Zarine River, the largest, which contributes to 41 % of surface water flows into the lake. The river flows are controlled by the Bukan Dam, the largest reservoir in the lake basin. The riverine lives in the basin are increasingly degraded, and the recipient lake is drying up. Allocation of environmental water requirements is of main priorities for restoration of the lake. The ecological needs of the river were investigated in three different reaches, upstream and downstream of the Bukan Dam. This paper presents a framework to address the evaluation of minimum environmental flows in this river system from nine eco-hydro methods. The overall results indicate that 17 to 35 % of mean annual flow (MAF) should be allocated for maintaining an acceptable minimum environmental requirement for saving the Urmia Lake. The allocated environmental flow releases from the Bukan Dam is to be increased from currently 9 to 35 % of MAF. The contribution from major rivers surroundings the Urmia Lake is also presented.