Tools The IMPETUS project employs a holistic approach for analyzing and forecasting the effects of the global change on water resources in the Ouémé River, a river catchment in Benin, located in West Africa. for Modeling Water Supplies Developing tools for decision support with ArcGIS Engine and Java By Rainer Laudien, Sebastian Brocks, Stefan Weyler, Alexander Christmann, Niklas Köhn, and Georg Bareth, BMBF Project IMPETUS Westafrika at the University of Cologne Editor's note: The IMPETUS research project (Integrated Approach to the Efficient Management of Scarce Water Resources in West Africa) is incorporating GIS in the Spatial Decision Support Systems that are being developed. This lets IMPETUS provide decision makers with a more holistic and interdisciplinary approach when developing scenarios related to present and future problems with freshwater supply. A previous article about this project appeared in the Summer 2008 issue of ArcUser. "Visualization, Interpretation, and Evaluation—Building a multitemporal Spatial Decision Support System (SDSS) scenario view with ArcGIS Engine" described the technical SDSS framework of IMPETUS. Although this article focuses on the tools developed for the project, an overview of the use of GIS in the IMPETUS project is included. The goal of the IMPETUS project is the development of management options for different components of the hydrological cycle using the SDSS tools. Because decision making requires an exhaustive knowledge of the processes, driving forces, possibilities, and stakeholders, ArcGIS Engine was used in computer-based SDSSs to handle huge amounts of data and provide visually attractive, reliable, and convincing displays of that data to users. Functionality developed for three of the ArcGIS Engine-based SDSSs will be discussed. Explicitly designed to provide a decisionmaking environment that enables the analysis of geographic information to be carried out in a flexible manner, SDSSs help researchers and managers make decisions. Modern computerbased SDSSs are comprehensive and complex systems that compile individual decision steps into an overall software structure and include spatial data, quantitative, and/or qualitative models with expert knowledge. SDSSs can be customized to the needs of individual users based on a given logical decision tree that has been predefined by users and developers during the design process. These systems are developed based on predefined, multifarious logical decision trees focused on a specific question. In the case of the IMPETUS project, that question was how to create an integrated 16 ArcUser Fall 2009 approach to the efficient management of scarce water resources in West Africa. By providing users with access to large amounts of significant spatial data, SDSSs are powerful problem-solving tools that often use a GIS component to add spatial analysis functionality. The ability of GIS to layer spatial and attribute data distinguishes this technology from many other decision support systems. Materials and Methods To include GIS and remote-sensing functionalities in the SDSSs, the Esri developer library for ArcGIS Engine 9.2 was used to program these systems. With ArcGIS Engine, a software developer can implement spatial analysis functions within computer-based spatial decision tools. To execute these SDSSs, the Java Runtime Environment (JRE) and ArcGIS Engine must be installed on the computer. The SDSSs were developed using the Eclipse software development kit (SDK). During the programming process, specific ArcGIS Engine components and other libraries, such as the POI-HSSF components furnished by Jakarta POI Java API for reading Microsoft Excel '97 file formats, were used in addition to standard JavaBeans [the reusable software components of the Java 2 platform]. Alphanumeric data and rasters, vector, and www.esri.com