Design storm prediction and hydrologic modeling using a web-GIS approach on a free-software platform E.M. Castrogiovanni a, * , G. La Loggia b , L.V. Noto b a Regione Siciliana-Ufficio Idrografico Regionale, via G. Bonsignore 1, I-90135, Palermo, Italy b Dipartimento di Ingegneria Idraulica ed Applicazioni Ambientali, University of Palermo, Viale delle Scienze, Palermo, Italy Received 13 April 2004; received in revised form 15 December 2004; accepted 16 December 2004 Abstract The aim of this work has been to implement a set of procedures useful to automatise the evaluation, the design storm prediction and the flood discharge associated with a selected risk level. For this purpose a Geographic Information System has been implemented using Grass 5.0. One of the main topics of such a system is a georeferenced database of the highest intensity rainfalls and their assigned duration recorded in Sicily. This database contains the main characteristics for more than 250 raingauges, as well as the values of intense rainfall events recorded by these raingauges. These data are managed through the combined use of the PostgreSQL and GRASS-GIS 5.0 databases. Some of the best-known probability distributions have been implemented within the Geographical Information System in order to determine the point and/or areal rain values once duration and return period have been defined. The system also includes a hydrological module necessary to compute the probable flow, for a selected risk level, at points chosen by the user. A peculiarity of the system is the possibility to querying the model using a web-interface. The assumption is that the rising needs of geographic information, and dealing with the rising importance of peoples participation in the decision process, requires new forms for the diffusion of territorial data. Furthermore, technicians as well as public administrators needs to get customized and specialist data to support planning, particularly in emergencies. In this perspective a Web-interface has been developed 0169-8095/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.atmosres.2004.12.015 * Corresponding author. Tel.: +39 091 7079583. E-mail addresses: mcastrogiovanni@uirsicilia.it (E.M. Castrogiovanni), glal@idra.unipa.it (G. La Loggia), valerio@idra.unipa.it (L.V. Noto). Atmospheric Research 77 (2005) 367 – 377 www.elsevier.com/locate/atmos