Exploring responses of lake area to river regulation and implications for lake restoration in arid regions

Many of the world's lakes in arid endorheic basins are shrinking at alarming rates, reducing habitat and economic benefits. Lakes are commonly recovered by river regulation. However, the scarcity of water has hindered the restoration of lakes in arid regions. There is therefore an urgent demand for insight into efficient and sustainable restoration of lakes. Here a water mass balance model was used to explore the impact of flow regulation scenarios on the restoration area of East Juyan Lake (EJL), which is located in an arid zone of China. Then a fractional water loss index was introduced to examine the water storage efficiency of the lake. Results showed that the lake ecosystem has been effectively restored due to the increased streamflow entering the lake caused by the Ecological Water Diversion Project; the dynamic recovery process of lake area is related to the initial area, and streamflow input and evaporation jointly determine the lake equilibrium. Affected by lake topography, fractional water loss index responded nonlinearly to the lake area. Based on these, we determined the appropriate restoration area of 42 km(2), and a discharge of 0.608 x 10(8) m(3) of water must be maintained continuously every year to sustain this area. This paper has provided an efficient way to restore and manage lakes at their suitable size by river regulation and water transfer projects, which are important in helping policy makers make robust decisions to facilitate sustainable development in arid regions.