土地利用方式变化对水循环过程响应机制研究

以挠力河流域为研究区,利用1990年和2013年土地利用类型,结合基于格子玻尔兹曼方法(LBM)的TOPMODEL模型定量评价了土地利用方式变化对水循环时空变化过程的影响。结果表明:基于LBM法的TOPMODEL模型可以很好模拟挠力河流域降雨径流水循环过程,对研究区具有较高的适用性;研究区林地、草地和建设用地面积变化不大,对于土地结构变化贡献比较小,而未利用地和旱田部分转为水田对土地结构变化贡献大;由于种植水田,导致5月到10月间的流域总蒸散发量增加、根系区缺水量减少、非饱和带缺水量减少、地表水量减少、地下水量增加;蒸散发增幅达8.9%,根系区缺水量降幅达10.5%,地表水量减少达43%;水田对水文情势影响的差异主要体现在水稻生育期的差异上,分蘖期对蒸散发量、根系区缺水量和非饱和带缺水量影响较大;水田灌溉对水循环过程的影响按变化幅度从大到小的顺序为非饱和带缺水量、根系缺水量、蒸散发量、入根系区水量、出根系区水量和地下径流量,其中入根系区水量差值和出根系区水量差值接近。

Mechanism of Response of Land Use Change to Water Cycle Process

Based on the farmland distribution maps of Naolihe River Basin in 1990 and 2013, the influences of paddy farmland and cultivation activity on temporal and spatial variation of water cycle process were analyzed quantitatively, combining with TOPMODEL model based on LBM method. Results showed that TOPMODEL model based on LBM method could simulate well the rainfall runoff process of Naolihe River Basin, and it had a high applicability on the investigated river basin. The area of forest land, grassland and construction land was not changed much, which contributed little to the change of land structure, while unused farmland and dry farmland were partly converted to paddy farmland, contributing obviously to the change of land structure. The presence of paddy farmland resulted in the increase of total evapotranspiration, decrease of the water deficit in root zone, decrease of water deficit in the unsaturated zone, decrease of surface water, and increase of underground water from May to October. Evapotranspiration was increased by 8.9%, water deficit in the root area was decreased by 10.5%, and surface water was decreased by 43%. Paddy farmland showed different effects on hydrological variables when rice was in different growth stages. It had great influence on evapotranspiration, water deficit in root zone and water deficit in unsaturated zone when rice was in tillering stage. The influence of paddy farmland irrigation on different water cycle processes was diminished in the sequence of SBAR, RZ, E, water quantity in inlet of root zone, water quantity in outlet of root zone, and RG, among which the differences of water quantity between irrigation and non-irrigation were almost the same for the inlet and outlet of root zone.