Die Anwendung ökohydraulischer Modelle auf hydraulische und wasserwirtschaftliche Problemstellungen

摘要

Ecohydraulics includes the role of physical processes such as hydraulics, sediment transport, and geomorphology in ecological systems. In recent decades, a number of numerical models were developed for simulating hydraulic, hydromorphological, and ecological processes. There are very few model systems existing which could simulta-neously simulate hydromorphodynamic processes, habitat quality distributions, and population status. Therefore, this research work aims to develop an ecohydraulic model system which combines advanced numerical methods and ecological theories to explore the dynamics and interplay between fluvial processes in rivers and the quality of physical habitat for fish and their density distribution.The main objective of this study is to develop fish habitat suitability and fish popula-tion models as well as to incorporate these models into a hydromorphodynamic soft-ware. The fish habitat suitability models assess habitat quality based on abiotic pa-rameters, namely flow velocity, depth, substrate, and temperature (if relevant), all of which are derived from the 2D hydromorphodynamic numerical model system TE-LEMAC. The relationships between these parameters and habitat features are repre-sented as habitat suitability curves. Four different methods are used to combine these curves into global indices of habitat quality. The quality of habitat can therefore be predicted for a given stretch of river under certain flow conditions. Two different sim-ulation models of population dynamics of fish are developed. The first model is con-verted from a logistic population concept, where model parameters are related to the time-dependent fish habitat conditions (e.g. weighted usable areas and overall suita-bility index). The second model is based on an age structured model concept with numbers as the only state vector. Age-specific fecundities and survival rates depend on the habitat qualities defined. The hydromorphodynamic, habitat, and population models are linked together in one model system.The practical applicability of the developed system to ecohydraulics modelling was explored through three case studies and compared with as well as validated using available observed data. On the basis of the calculated results, the model system is proven to be efficient in describing population dynamics of the European grayling (Thymallus thymallus. L.) in the Aare River in Switzerland. Satisfactory predictions of the long-term population evolution of the rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and flannelmouth sucker (Catostomus latipinnis) in the Colorado River in the United States were obtained. Furthermore, the effects of the Da-Wei Power Plant in the Jiao-Mu River in China on the schizothorax (Schizothorax) and schizothorax (Racoma) fish species were investigated. The efficiency of fish stocking strategies was evaluated and optimal fish stocking numbers were also pro-posed. The developed ecohydraulic model system provided very promising results, which highlighted the fundamental role of the temporal variability of hydromorpho-logical parameters in structuring populations of fish species. Simulating population trends in anticipation of any changes in water management mode, using the software developed in this study can provide decision-makers with useful information to opti-mise their management measures.