SENSITIVITY OF COASTAL AQUIFER MANAGEMENT DESIGN TO UNCERTAINTY

Coastal aquifer management through the application of optimization design is challenging when fresh water demands are high for coastal communities. The fresh water in coastal aquifers is underlain by salt water, and when the water is extracted from the ground, salt water is often drawn into the fresh water zone. This process is called salt water intrusion. Salt water intrusion threatens the purity of the water in the wells, and can have serious affects upon ecologic systems that rely upon fresh water input from the aquifer. There are multiple sources of uncertainty in ground water modeling. In this study the effects of uncertain in hydraulic conductivity on coastal aquifer management designs is examined with respect to fresh water potential and risk of well contamination. The study utilizes the Ghyben-Herzberg approach to model the fresh water- salt water interface. This approach provides a worst case scenario for the risk factors. The model used for this study is a box model based upon the hydrologic dynamics of a coastal aquifer in New England. Various management designs are explored for a fixed supply problem. The uncertainty of the hydraulic conductivity is modeled using a multi-scenario approach. By quantifying the risk factors of these aquifers to ground water pumping, statistical analyses are used to perform sensitivity analysis of management designs.