Quantifying sediment resuspension linkages to nutrient enrichment in the existing and future Salton Sea
The UC Davis research involved a 24-month study (including a 4-month measurement program) in the Salton Sea to directly measure sediment resuspension using an array of OBS instruments and an acoustic wave height and current profiling instrument (AWAC). The data provided by these instruments, in conjunction with existing UC Davis temperature recording instruments in the Sea and the existing CIMIS meteorological network, point to the existence of a quasi-equilibrium condition for the suspension of sediments in the lake.
Non-linear relations were developed between the wind intensity and turbidity near which were in relative agreement with relationships from reviewed literature. In particular, the extended García and Parker formulation with DLM-WQ shows the best prediction to describe the seasonal trends as well as short-term variations. The relationship was incorporated into the existing DLM-WQ model.
DLM-WQ, combined with this new sediment model, was used to more fully explore the potential for ecological restoration of the Salton Sea under possible future configurations. Two scenarios, the North Sea Combined Alternative and South Sea Combined Alternative, as suggested by PEIR were examined. The simulation of North Sea Combined Alternative indicates that the Marine Sea might have a better eutrophic status than that of the whole Sea because of fewer sediment resuspension events due to lower average wind speed acting on a smaller surface. On the other hand, the simulation of South Sea Combined Alternative suggested that the concentrations of nutrients in the water column would be the same or higher than those of the whole Sea, because of more sediment resuspension events due to higher average wind speed and due to shallower water depth. In the both alternatives, however, the anoxia in the hypolimnion would be spatially and temporally increased due to increased stratification periods, during which time toxic substances (such as hydrogen sulfide) and organic materials could be accumulated in the sediments.
DLM-WQ with the new sediment algorithm successfully accounts for the dominant processes that control eutrophication in the current Salton Sea and provides an indication of variations in properties that could be expected in potential future configurations. In addition to being a tool for comparing future configurations, DLM-WQ provides a basis for designing future monitoring needs.