Integrated modelling of aquatic ecosystems in China: Ecohydrology and hydraulics

Catchment properties, in-stream processes, and their effects on aquatic organisms are closely linked, but the interactions of key driving forces, processes, and possible feedback mechanisms are not yet sufficiently understood. Aim of the project is the development of an integrated ecohydrological modelling approach to assess the impacts of fast environmental changes on aquatic ecosystems in the catchment of the River Changjiang in the Poyang lake region in China. Measuring and sampling campaigns jointly planned and conducted by hydrologists, hydraulic engineers, and hydrobiologists provide the basis for linking three different models: A dynamic DPSI-system (Driver-Pressure-State-Impact) is created, integrating the models SWAT (catchment processes), HEC-RAS (in-stream processes), and BIOMOD (species distribution). Major drivers such as climate, land use, and channel parameters are model input data, while the main pressures on the ecosystem (due to changes in hydromorphology, water and nutrient balances) are defined and represented in the model algorithms of SWAT and HEC-RAS. The changes of the abiotic state parameters, e.g. streamflow, water depth, and substrate, are temporally resolved in the model output. Finally, the impact of the modified hydrological and hydraulic conditions on the aquatic ecosystems will be evaluated by determining the occurrence probabilities and the possible shifts of distribution ranges of benthic macroinvertebrates modelled by BIOMOD. The paper presents the developed concept, the procedure of the field campaigns, and the first steps of the integrated ecohydrological and hydraulic modelling. The distribution of benthic macroinvertebrates estimated by the species distribution model is described in KUEMMERLEN et al.(2012).Original Abstract: Einzugsgebietseigenschaften, Gerinneprozesse und ihre Auswirkungen auf aquatische Organismen sind eng verknuepft, aber die Interaktionen zwischen den wesentlichen treibenden Kraeften, den Prozessen und relevanten Rueckkopplungsmechanismen werden bisher noch nicht vollstaendig verstanden. Das Ziel des Projektes ist die Entwicklung eines integrierten, oekohydrologischen Modellansatzes zur Darstellung der Auswirkung von schnellen Umweltveraenderungen auf aquatische Oekosysteme am Beispiel des Changjiang-Einzugsgebietes im Poyang-Gebiet in China. Von Hydrologen, Hydraulikern und Hydrobiologen gemeinsam geplante und durchgefuehrte Mess- und Probenahmekampagnen sind die Basis fuer die Integration von dr