基于CoupModel的三峡库区典型农林地水量平衡模拟

Water Balance Models of Typical Forestland and Farmland in Three Gorges Reservoir Area with CoupModel

应用CoupModel（土壤-植物-大气系统热量、物质运移综合模型），在野外观测试验的基础上对三峡库区典型阔叶林（木荷和石栎）、针叶林（杉木和马尾松）和农地（玉米）SPAC系统水量平衡进行了模拟。结果表明，土壤含水率模拟结果与实测值具有较好的一致性（R^2为0．80～0．91）；蒸散是水量平衡中主要的支出项，比例高达61％，蒸散量由大到小为阔叶林（720mm／a）、针叶林（700mm／a）、农地（601mm／a）；农地年均深层渗透量（452mm／a）分别比阔叶林、针叶林高60mm和47mm，且在降雨较多的年份表现更明显；试验期间阔叶林系统水分支出高于输入，这是引起阔叶林地土壤储水呈现负补偿现象的主要原因；水分盈余是农地水量平衡的主要特征，而林地却发生了春旱和秋旱，农林地水分条件具有较大差异。植被覆盖类型对水量平衡具有重要影响。在实施植被建设、退耕还林时，选择与当地水分条件相适应的树种、采取合理的抚育措施是必要的。

Based on field measurement, the CoupModel （Coupled heat and mass transfer model for soilplant-atmosphere system） was applied to simulate water balance in three kinds of vegetation types, including broadleaved forest （Schima superba and Lithocarpus glaber） , coniferous forest （Cunninghamia lanceolata and Pinus massoniana） and farmland （Zea mays） in Three Gorges Reservoir Area of China. The results showed that the simulated values of soil moisture were fairly consistent with measured ones and the determination coefficient （ R2 ） were 0. 80 to 0. 91. Evapotranspiration was main output of water balance with the percentage up to 61%, and the figures were ranked as follows： broad-leaved forest （720 mm/a） 〉 coniferous forest （700 mm/a） 〉 farmland （601 mm/a）. Annual simulated deep percolation decreased by 60 mm for broad-leaved forest and 47 mm for coniferous forest compared with that for farmland （452 mm/a） , and it was even greater in wet year. For broad-leaved forestland, water consumption was more than income during the experimental period, which was the main reason causing soil water deficit. The water balance of farmland was characterized by moisture surplus, while spring and autumn drought occurred in forestlands. There was obvious difference between forestland and farmland for water conditions. Model results indicated that the vegetation species significantly influenced the magnitude of water balance components, which called for further attention to the selection of tree-species when planning future afforestation projects. Forest tending should also be applied scientifically during the practice of vegetation restoration.