sedimentation and assessement of sediment release Andrea Maffio*, Alberto Elli*, Orsola Brasi*, Daria Gatti** 7th Int. Conf. on Hydroinformatics – HIC 2006 Nice France, 26-28 Aprile 2006 * CESI RICERCA ** CESI SpA Sedimentation in artificial reservoirs in hydropower systems and/or for irrigation and drinking water uses, brings about issues related to operational safety (e.g. clogging of dam bottom outlets) and environmental impact (e.g. on aquatic life) due to sediment release to the downstream water bodies. In the framework of the R&D "Ricerca di Sistema" Program, CESI has developed the software ITERS, a modeling-GIS integrated tool to support decisions for setting up actions to mitigate reservoir sedimentation and downstream environmental effects due to water and sediment release. ITERS allows user to analyze hydro- sedimentological processes in the watershed, reservoir, and downstream river considering different procedures and modeling approximations to be chosen depending on available data and study purpose. ITERS graphical user interface permits to carry out, in an integrated way, landscape data analysis (use is made of ESRI ArcGIS interface and 3D Analyst, Spatial Analyst extensions) as well as mathematical modeling predictive simulations based on hydrodynamics/transport equations and empirical laws (one- dimensional and two-dimensional schematization). Examples of results provided by ITERS are: watershed sediment yield assessment, digital elevation model representation, input data extraction from GIS, reservoir sedimentation and released water turbidity estimate during flood events or flushing maneuvers, sediment- induced impact on aquatic ecosystem in the downstream river due to reservoir emptying. To evaluate software functionality, implemented procedures and modeling results ITERS has been applied to study sedimentation in a reservoir located in the northern Italian Appennine.