GEOÖKO VOLUME/BAND XXXV, 39 – 77 GÖTTINGEN 2014 MANAGEMENT SUppORT By OpTIMIZATION-BASED TRADE-OFF ANALySIS – THE ExAMpLE OF BIODIESEL CROp pRODUCTION SVEN LAUTENBACH, MARTIN VOLK, MICHAEL STRAUCH, GERALD WHITTAKER & RALF SEPPELT SUMMARy Modeling in decision support applications has often been used to compare outcomes bet- ween alternative scenarios of decision options. he introduction of optimization methods enable the comparison of a very large number of scenarios that can be used to construct an approximation of Pareto optimal trade-ofs among competing objectives. hese represent the best compromise solutions that are available to the stakeholders. We show for the example of biodiesel crop production how such an optimization approach can be used to identify a set of potential solutions. We speciied the separate objectives of biodiesel crop production, food and fodder production, water quality and minimum discharge, and searched for the best trade-ofs among them using a relative recent optimization method. he analysis was based on an integrated river basin model (SWAT) and a multi-objective genetic algorithm (NSGA-II), and was set in the Parthe catchment in Central Germany. To ease communi- cation with stakeholders and decision makers, we identiied clusters in the results through use of a self organizing map approach. he clusters represent solutions of similar manage- ment strategies for the watershed, from which decision makers and stakeholders can select suitable compromise solutions. he efects of increased biodiesel crop production on the other objectives were mainly triggered by the share of silage corn and sugar beets in the crop rotations. Generally speaking, negative efects on low low caused by increased biodiesel crop production in the region could be avoided by a shift from silage corn to sugar beets or a reduction of total crop yields. Nitrate concentrations were more sensitive to total crop yield by bioenergy and food and fodder crops. Keywords: River Basin Management, water quality, bioenergy, land use, genetic algorithm, crop rotation schemes, self organizing map, optimization, trade-offs ZUSAMMENFASSUNG Simulationen im Umweltbereich werden oftmals eingesetzt um die Ergebnisse unterschied- licher Szenarien miteinander zu vergleichen. Mithilfe von Optimierungsansätzen lassen sich darüber hinaus potentielle Managementmaßnahmen in sehr hoher Zahl vergleichen. Auf