Effects of Deep Pool on the Salinization of Coastal Reservoir

Coastal reservoir contributes to alleviate the freshwater shortage in stressed areas, and the salinization of reservoir water is one of the most important challenges that coastal reservoir faced. Field-investigation indicates that there are many deep pools located at reservoir bed, and large amount of high-salinity water was found within deep pool which was hardly be desalted. Laboratory experiments and numerical simulations with different depth and locations of deep pools were conducted to further discuss the influence of deep pool on the salinization of reservoir and adjacent aquifer. The experiments showed that deep pool has greatly increased the salinity of reservoir water due to high-salinity water stored in the deep pool, which may act as an extra source of saltwater to coastal reservoir during dry season. The increasing depth of deep pool was found to have negative impacts on the salinity of reservoir water, and as the distance from the deep pools to dam increased, the salinization extent in coastal reservoir decreased. Salinity data from the numerical simulations in coastal reservoirs and adjacent aquifer were matched the experimental data well. Flow field results from simulation indicate that there is a high exchange capacity zone occurred from the deep pool to seaward boundary, which gave the reasonable reasons for the existence of high-salinity water within deep pools. The salinity stratification in deep pool and adjacent aquifer was also found, for water in deep pool, the highest salinity zone formed at the bottom of deep pool, and for adjacent aquifer, it ordinary formed at seaward boundary. The findings highlight the significant influence of deep pool on the salinization of coastal reservoir, and give the probable reasons for the salinization of reservoir water in dry seasons. They may improve the water management for coastal reservoir and thus contributes to the water resource utilization in coastal area.