Development of Watershed Modeling Systems for a Comparative Study of Three Conceptual Hydrologic Models on Two Medium-sized Catchments in Poyang Lake Basin

Principal Investigator:
Chen, David Yongqin

Co-investigator(s):
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Summary:
Poyang Lake, located south of the Yangtze River, is the largest fresh-water lake in China. Five major rivers (Ganjiang, Fuhe, Xinjiang, Raohe, Xiushui) drain into Poyang Lake which discharges into the Yangtze River at Hukou. The "Century Project" for sustainable development of Mountain-River-Lake (MRL) ecosystem of the entire Poyang Lake drainage system has extensively attracted international attention and will continue to be a vital project of watershed management and restoration in China into the 21th century. Flooding has been a major hazard causing severe economic losses and ecological damages in Poyang Lake drainage system. To forecast and control floods and to characterize the hydrologic variations of Poyang Lake and its interactions with the Yangtze River, a hydrologic model is urgently needed to simulate and predict the hydrologic regimes of the five river basins.

To develop a watershed modeling system for hydrologic calibration and validation on the entire Poyang Lake drainage system is obviously a tremendous task. It is proposed in this study to start with two mid-order and medium-sized catchments of several hundred square kilometers and with diversified and representative land use/land cover patterns. Three widely used conceptual hydrologic models (two American models, HEC-1 and HSPF, and one Chinese model, the Xinanjiang model) will be tested on the two study catchments and compared to each other with an emphasis on model performance for examining the validity and suitability of models. GIS-based watershed modeling systems of the two study catchments will be developed to integrate drainage features and watershed characteristics such as land use/land cover, vegetation, and soils in digital spatial databases. The two systems will be used to conduct terrain analysis and watershed characterization for developing hydrologic model inputs and to analyze and display the flood-prone areas based on runoff simulation results. This model intercomparison study will not only contribute to the scientific understanding of the validity and suitability of conceptual hydrologic models for typical catchments in east central humid region of China, but also provide practical experience and implications for choosing and applying hydrologic models for the development of flood forecasting and control system for the entire Poyang Lake drainage system in the future. The modeling systems and simulation results of this study will be highly valuable resources for watershed management and restoration activities that are vital to the social and economic development in the Poyang Lake drainage system. In particular, the influence of the Three Gorges Dam on the hydrologic interactions between Poyang Lake and the Yangtze River will need to be assessed using a suite of robust hydrologic models which will be used and tested in this study.