2.1. Study area
Nansi Lake (NSL) is an important storage hub of the SNWD-ERP. This lake is located in western Shandong Province (WSD), (34°27′ to 35°20′ N and 116°34′ to 117°21′ E). NSL consists of four sublakes: the Nanyang, Dushan, Zhaoyang and Weishan sublakes, extending from north to south. NSL is the largest lake in North China, with a water area of 1,266 km2 and 53 inflowing rivers. NSL is situated in a warm temperate zone, and the climate is a subhumid continental monsoon climate with 700 mm of annual precipitation. The evaporites in WSD are dominated by rock salts and gypsum salts, and gypsum salts (gypsum mines) are mainly distributed in the southwestern portion of WSD (Qi, 2010 ).