Goal Programming Models for Determining Freshwater Inflows to Estuaries

Abstract

This paper presents two multiobjective models for the estuary‐management 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. Salinity is expressed as a function of freshwater inflow in a nonlinear‐regression equation, which is used as a constraint. Additional nonlinear constraints are the harvest‐regression equations for the various species 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 non‐linear optimization system (GAMS/MINOS) programming code. Because of the uncertainty associated with the regression equations for salinity and harvest, a second formulation was developed in which the constraints are expressed in a chance‐constrained formulation. The chance‐constrained goal‐programming model is solved by using the GRG2 programming code. The models for both formulations are applied to the Lavaca‐Tres Palacios Estuary in Texas.