Within the frame of the research project "Improved approaches for water resources management for intensly used watersheds based on integrated benefit and risk assessment (WSM-300)" sponsored by Deutsche Bundessstiftung Umwelt, a methodology is developed which guides and supports an improved water resources management on the level of small watersheds (up to 300 km²). The developed methodology is to be implemented into a software based tool within the framework of a generic Decision Support System (DSS). Ihwb is mainly participating in the research project with the case study Modau .

The EU Water Framework Directive requires the achievement of good ecological status of water bodies until the year 2005. After the survey of the current status, Germany is now in the monitoring phase. Beyond the necessary in field measurments simulation models can contribute in this phase.

For the case study of the Upper Modau and the flood control reservoir Ober-Ramstadt (located in Hessia, Germany) the suitability of water quality models to achieve the aims of the EU Water Framework Directive is analysed.

Since midyear 2005 in Hessen five pilot projects are in progress. The projects should prepare the compilation of the river basin management plans by testing several working steps, whereas each project has specific exigencies.

By the end of 2006 a river basin plan for each surface water body and two groundwater bodies in the watershed of the Modau must be published (Pilotprojet Modau ). The development of the river basin plan and the implemented program of measures as specified in Annex VI and VII of the WFD are based on the results of the survey report and the monitoring programs. In a first step it has to be determined in how far the environmental objectives of the relevant water bodies can not be achieved. The gap analysis identifies the discrepancy between the current status of a water body and the required (good) status. Based on this, adequate measures to improve the status of the water bodies have to be analysed. The analysis should result in a combination of measures which improve the status of a water body most efficiently. The final reports of the single pilot projects are published on the homepage of the 'Hessisches Ministerium für Umwelt, ländlichen Raum und Verbraucherschutz' (HMULV ) (in german).

Traditionally urban and rural hydrology is treated from a different point of view, usually from different engineering disciplines as well. However, recent development in european water politics (European Water Framework Directive) calls for a rather integrated view in managing our water resources; this also includes an integrated view of rural and rural areas and their interactions.

Aim of this work is to develop an approach to integrate a detailed modelling system for urban areas in a grid-based, GIS-coupled modelling system for natural catchment hydrology. The integrated modelling system will allow to study the influence of urban areas on natural stream flow on a detailed basis by explicitly considering interactions of waterflow between urban and rural areas.

The purpose of the SMUSI model is the simulation of pollution load in urban sewer systems. This model is used to determine the dimensions of constructions for water pollution control in combined sewer systems. The SMUSI model allows to prove to the controlling authorities that the limits for dirt discharge are not exceeded. The model is available to the experts community against payment of a licence fee.

The sofware runs on any normally equippted pc. It is especially suitable for use in enineering agencies charged with the planning of urban sewer systems. The Hessisches Landesamt für Umwelt und Geologie is responsible for the distribution of SMUSI 5.0. IHWB no longer provides free support. Paid support is available upon request.

Computer based simulation models are widely used in water resources management. The knowledge of basic physical processes is still limited, so models are always a simplified representation of the regarded system. For this reason model results should be considered as estimates or predictions with uncertainty as inherent attribute. The sources of model predictive uncertainty are diverse.

The objective of this research is to derive a methodology to (1) quantify and include different sources of uncertainty in hydrological models (2) to analyse their impact on model results both separately and collectively in order to (3) achieve a more complete information of model predictive uncertainty as an important requisite for (4) an improved assessment of risks.

Furthermore this is expected to provide more detailed insight into validity of models and model parts, to give valuable indications of possibilities to reduce uncertainty, to augment model performance and reliability and increase information content and credibility of model results.