典型喀斯特植被类型条件下绿水循环过程数值模拟

绿水对于喀斯特地区的生态恢复具有重要意义。从绿水循环过程入手,综合考虑冠层截留过程、土壤水分运动过程和植被蒸散发过程,建立典型喀斯特地区不同植被类型条件下的绿水循环过程模型。模型在小型人工模拟降雨实验和长时段监测数据的验证下,依托遥感和GIS手段,扩展到区域尺度,模拟了研究区2005年10月~2006年3月的绿水循环过程,结果表明:(1)研究区的绿水占了降雨量的87.4%,大部分降水通过冠层截留、蒸散发和入渗转化为绿水,供给生态用水。(2)典型喀斯特地区不同植被类型条件下绿水循环存在重要差异,随着喀斯特生态恢复和植被类型改变,生态系统把更多的降雨转化为绿水,即转化为生态用水。(3)模拟时段内的绿水贮存量呈增大趋势,不易发生干旱,是"春旱"和"夏旱"前绿水补充的重要时段。

The numerical simulation on green water cycle of typical vegetation types in karst area

Green water is vital to vegetation recovery in karst area. Considering the processes in green water cycle, this paper coupled the canopy interception process, soil moisture movement process and evaportranspiration process, and built a green water cycle processes model to simulate and analyze green water cycle of typical vegetation types in karst area. Under the rainfall simulation experiment calibration and soil moisture monitor calibration, the model was extended to regional scale, and was used to simulate the green water cycle in a karst area, Guizhou Province, China, during October 2005 to March 2006. The results show that: First, most of the rainfall during this period turns into green water through canopy interception and infiltration into soil, which totally occupies 87.4% of rainfall and is supplied for vegetation ecosystem water use. Second, there are many differences in green water cycle processes of different vegetation types in the study area. The percentages of green water of different vegetation types are 93.3%, 93.2%, 91.5%, 81.9% for shrubs, coniferous woodland, mix woodland, grassland respectively. It can be concluded that with the vegetation recovery from grassland to shrubs and woodland in the study area, there will be more and more rainfall turning into green water which is used by the vegetation ecosystem and benefits the vegetation recovery. Third, the changes of green water cycle between months in different vegetation types share the same characteristics. The green water storage is increasing in October, January, and March in all vegetation types, and is decreasing in November, December, and February. In this period, the amount of green water is much greater than that of blue water, and the green water storage is increasing overall. Drought is unlikely to occur during October to March and the green water storage is supplemented in this period before the "spring drought" and "summer drought" in this karst area.