Contents & Foreword, Characterizing And ... - IRRI books

Framework for exploratory and predictive land-use analysisThe generic methodology for exploratory and predictive regional land-use analysisconsists of a (multiple-goal) optimization model, an “engine” to calculate inputs andoutputs of land-use systems, and a GIS (Fig. 1). This methodology was named SOLUS(sustainable options for land use) by Bouman et al (1999a) and Schipper et al (2000).The same elements also form the building blocks of the land-use planning and analysissystems (LUPAS) developed for exploratory studies in four regions of Asia (Roetteret al 1998). Regional characterization or land evaluation in the widest sense includesthe assessment of resource availability and land suitability and quantification of theinput-output relations of the various land-use systems (Laborte et al 1999).OptimizationThe optimization model is constructed using linear programming techniques. It selectsland-use systems for the area under consideration by optimizing toward a specificgoal. This goal may be the maximization of economic surplus in the agriculturalsector, maximization of employment, minimization of certain environmental effects,or maximization of some household utility function. The optimization model mayalso be of the multiple-goal type in which subsequent optimizations are performedtoward different goals. An optimization goal in linear programming models is implementedby a so-called objective function. Optimizations are performed under constraints,which may be absolute, for example, no more land can be used than is availablein the area, or normative, for example, minimum threshold boundaries may beimposed on the production of a given crop or on certain sustainability parameters.The optimization of a certain objective function under a set of coherent constraints,and using a specific set of land-use systems to choose from (see below), is called ascenario. Trade-offs between economic and sustainability objectives are quantifiedby running the model for different scenarios.GeographicdataGeographicinformation systemMapsProblemdefinitionNongeographicdataTechnicalcoefficientgeneratorScenariosLinear programmingmodelTables,reportsAnalysis and user interactionFig. 1. Schematic illustration of the land-use exploration frameworkSOLUS. Boxes are models/tools, ovals are data, solid lines are flowof data, dotted lines are flow of information.474 Bouman et al