Optimal safe groundwater yield for land conservation in a seashore area under uncertainty

This paper presents a procedure for estimating safe yield of a 3-layer aquifer groundwater system. First, based on Darcy's Law, a set of equations is derived to describe the groundwater flow regime. The estimation of parameters for these equations is based upon observations on water-well elevation and natural recharge. These equations then serve as building blocks for a linear programming model, which maximizes groundwater extraction while subjected to minimum water-table elevation requirements for the prevention of saline intrusion. The model is compact, transparent and flexible for handling different patterns of natural recharge and well field. Uncertainty in system modeling and parameters estimation is explicitly dealt with by gray linear programming. To test the usefulness of the procedure, this paper presents the results of a case study of the Chou-Shui-Chee alluvial fan in Taiwan. The 3-layer aquifer is sliced into 19 computational cells. Based on natural recharge estimates and existing extraction well distribution, estimated safe yield is about 1/3 of the natural recharge rate under the restriction that the groundwater table at the outflow to the Taiwan Strait is at least 2 m above mean sea level.