Multi-Objective Optimization Approach for Land Use Allocation Based on Water Quality Criteria

Abstract

This research applies a multi-objective optimization linear programming (MOLP) approach considering uncertainties associated with decision variables for the evaluation of multiple scenarios to obtain sustainable strategies for optimal land use growth and distribution in the Ro Grande de Arecibo watershed, Puerto Rico. The studied scenarios consider several factors including primarily environmental, physical, and social and economical factors as part of a decision making process. This approach is one of the components together with a GIS model for a land allocation system.A multi-objective optimization approach is used to optimize several independent objectives simultaneously. The objective functions lie in the need to address the environmental goals in order to meet the water quality standards imposed by the United States Environmental Protection Agency (USEPA) and the local Puerto Ricos Environmental Quality Board (PREQB) in terms of nutrient loadings of total phosphorus (TP), total nitrogen (TN) and otal suspended sediments (TS).The analysis developed in this research use the results from a water quality analysis and simulation for a ten-year period (1995-2005) using the Hydrological Simulation Program Fortran (HSPF). The watershed simulation includes the hydrology, sediments and nutrients components (Total Nitrogen species and Total Phosphorus). These variables will provide data to generate the annual loadings and annual export coefficients intervals of the simulated species by land use in the watershed and used as input in the optimization analysis.A total of six different hypothetical scenarios were evaluated reflecting possible conditions in the future growth pattern at the watershed in the time study horizon (year 2025). Findings of this research will provide the base work to find possible solutions to difficult issues related to land use planning maintaining the viability of water quality and quantity.