Analysis of long‐term water balance in the source area of the Yellow River basin |
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Authors: | Yoshinobu Sato Xieyao Ma Jianqing Xu Masayuki Matsuoka Hongxing Zheng Changming Liu Yoshihiro Fukushima |
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Institution: | 1. Research Institute for Humanity and Nature, 457‐4 Kamigamo‐motoyama, Kita‐ku, Kyoto 603‐8047, Japan;2. Frontier Research Center for Global Change, 3173‐25 Showa‐machi, Kanazawa‐ku, Yokohama 236‐0001, Japan;3. Department of Forest Science, Kochi University, 200 Monobe‐Otsu, Nankoku, Kochi 783‐8502, Japan;4. Key Laboratory of Water Resources and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences, Beijing, People's Republic of China |
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Abstract: | To analyse the long‐term water balance of the Yellow River basin, a new hydrological model was developed and applied to the source area of the basin. The analysis involved 41 years (1960–2000) of daily observation data from 16 meteorological stations. The model is composed of the following three sub‐models: a heat balance model, a runoff formation model and a river‐routing network model. To understand the heat and water balances more precisely, the original model was modified as follows. First, the land surface was classified into five types (bare, grassland, forest, irrigation area and water surface) using a high‐resolution land‐use map. Potential evaporation was then calculated using land‐surface temperatures estimated by the heat balance model. The maximum evapotranspiration of each land surface was calculated from potential evaporation using functions of the leaf area index (LAI). Finally, actual evapotranspiration was estimated by regulating the maximum evapotranspiration using functions of soil moisture content. The river discharge estimated by the model agreed well with the observed data in most years. However, relatively large errors, which may have been caused by the overestimation of surface flow, appeared in some summer periods. The rapid decrease of river discharge in recent years in the source area of the Yellow River basin depended primarily on the decrease in precipitation. Furthermore, the results suggested that the long‐term water balance in the source area of the Yellow River basin is influenced by land‐use changes. Copyright © 2007 John Wiley & Sons, Ltd. |
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Keywords: | Yellow River basin source area hydrological model water balance land‐use change |
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