GOAL PROGRAMMING-MODELS FOR DETERMINING FRESH-WATER INFLOWS TO ESTUARIES

This paper presents two multiobjective models for the estuary-manageme nt problem based upon goal-programming procedures. The multiobjectives are the minimization of freshwater inflow into bays and estuaries and the maximization of commercial-fish harvest for five fish species. Sa linity is expressed as a function of freshwater.inflow in a nonlinear- regression equation, which is used as a constraint. Additional nonline ar constraints are the harvest-regression equations for the various sp ecies that express harvest as a function of the quantity of freshwater inflow. The goal programming model is a nonlinear-programming problem solved by using the general algebraic modeling system/modular in-core nonlinear optimization system (GAMS/MINOS) programming code. Because of the uncertainty associated with the regression equations for salini ty and harvest, a second formulation was developed in which the constr aints are expressed in a chance-constrained formulation. The chance-co nstrained goal-programming model is solved by using the GRG2 programmi ng code. The models for both formulations are applied to the Lavaca-Tr es Palacios Estuary in Texas.