Seasonal Interaction of River Water-Groundwater-Salt Lake Brine and Its Influence on Water-Salt Balance in the Nalenggele River Catchment in Qaidam Basin, NW China

Identifying interactions among river water, groundwater and salt lake brine is important for sustainable exploitation of brine mineral resources. In this study, we investigated the water exchange rate in dry and wet seasons, and assessed the influence of seasonal water exchange on brine concentration and crystallization process in the Nalenggele (NLGL) catchment of Qaidam Basin, China. The results show that the surface water infiltration and groundwater recharge rates in the wet season were 2.81 × 10−3 and 1.15 × 10−3 m3/(s·m) in upstream, 1.63 × 10−2 and 1.53 × 10−2 m3/(s·m) in midstream, and 2.83 × 10−4 and 6.82 × 10−5 m3/(s·m) in downstream, respectively; while their counterparts in the dry season were 9.81 × 10−4 and 5.05 × 10−4 m3/(s·m) in upstream, and 8.34 × 10−3 and 7.78 × 10−3 m3/(s·m) in midstream, respectively. The water exchange strongly influenced brine concentration and crystallinzation process, with brine chemistry belonging to 3K2SO4·Na2SO4 and KCl types in wet and dry seasons, respectively. The strong water exchange in wet season destroyed the water-salt balance, while the low water exchange rate in dry season facilitated preparation of KCl products.