Weighted Usable Volume - Habitat Modeling

Habitat research goes back for several decades. The importance of diversify available habitat for aquatic biota has been shown by many authors throughout the last years. In order to understand complex natural river structures and to analyze functional interactions between aquatic biota and abiotic components of the environment many methodologies were developed with the main goal to provide practical tools for river management. One of the most used models is the "Physical HABitat SIMulation model, PHABSIM" (Bovee 1982). In nearly every model the principals of the PHABSIM - model will be applied. These models nonnally calculate the "Weighted Usable Area" (WUA) for aquatic organisms under specified environmental conditions. Weighted usable area as a result of mean velocity data in verticals or transects do not describe the real world situation of velocity distributions in rivers cause of data smoothing. Instream flow modelers are nowadays increasingly utilizing 2 D and 3 D hydrodynamic modeling approaches to assess aquatic habitat versus discharge relationships. Out of technical increase of instrumentation, resolution and sampling strategies, new possibilities out of the use of acoustic Doppler or laser 3 D profilers open new vistas within hydraulic- and habitat modeling. As an example the fnkage between energy intake and use, which is used in bioenergetic models, necessitates a very detailed description of the study site with a 3 D velocity field. For further development in habitat modeling, the use of WUV (weighted usable volume) as a result of a special velocity distribution, which describes the real world of living space without data smoothing consequentially is a raust. The important and decisive differente between the existing habitat models and the new model is the integration of the whole infonnation of spatial distribution of the flow velocity within a river system or reach into the habitat model by using WUV (weighted usable volumes). Our principal object is to set up new software components for standardized calculation methods of physical parameters to analyze available living space. The main project aim is the integration of the whole infonnation of spatial distribution of measured or simulated velocilies into habitat models. As a final result of the new modeling strategy the real world of livable space and its within-year fluctuations will be shown.