rivers

GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers) is a model system for predicting chemical fate and exposure in surface waters. The GREAT-ER approach combines a series of well studied models (for sewers, waste water treatment plants and rivers) with spatial information managed by a GIS. A new version of GREAT-ER (version 2) has been developed which has a number of improved features com-pared to its predecessor. All components are now implemented as Free Software and make use of Free Software where possible. This simplifies the distribution, use and extension of the system and its components for scientific applications. In addition, two new platform-independent user interfaces have been developed. The first is a simplified web-based inter-face for easy access without installation and the second is a full-featured desktop version. The model system has been redesigned to increase its flexibility for the modification and extension of its component models. In addition, the file-based data storage system used in version 1 has been replaced by a database management system with a flexible Appli-cation Programming Interface (API). This makes it easier for users to share their results, using a new repository (also with web-based and desktop versions) serving as a central communication tool. The output from the new system has been successfully tested against the field-validated models in GREAT-ER 1.0