基于水文模型与遥感信息的植被变化水文响应分析

Analysis on hydrological response to the change of vegetation based on the hydrological model and remote sensing information

针对地表覆被改变带来的流域水文响应存在不确定性这一问题,为了探索我国南方山区植被变化下的水文过程时空演变规律,依据东江流域的土地覆被类型,结合野外调查试验与遥感数据提取典型植被特征信息,利用考虑水文、地形、土壤、植被等多要素综合的分布式水文模型DHSVM,对流域内各种典型覆被情景下的水文过程进行模拟,进而分析植被变化引起的径流、蒸发、土壤水变化的响应关系。结果表明:大面积人工种植桉树林,将会对流域水文过程产生较大影响,地表径流深比现状针叶林增大17.5%,蒸散发量减小18.1%,洪峰流量也有所增加,流域洪水灾害发生概率加大;当流域现有针叶林生态系统退化为草地时,多年平均径流量增加24.4%,蒸散量减少25.3%,不利于自然流域的水源含蓄;针叶林、阔叶林和混交林三类森林植被更替对流域的水文过程影响相比其他植被类型要小。研究成果为分析流域变化环境下的水文过程时空演变规律及其生态环境效应提供参考,对我国南方山区水资源管理规划和生态环境保护具有实际意义。

In view of the uncertainty of hydrological response of the watershed caused by the surface cover change in watershed,this paper aims at exploring the laws of temporal and spatial evolution of hydrological processes under the change of vegetation in mountainous areas in southern China.Combined with the remote sensing data,the information of typical vegetation features through the field investigating experiments are determined.The Distributed Hydrological Soil Vegetation Model(DHSVM)considering multi-factors,e.g.hydrology,topography,soil and vegetation,is used to simulate the hydrological processes under different scenarios of typical vegetation cover in the watershed.Then the response of runoff,evapotranspiration and soil moisture caused by the change of vegetation is analyzed.The results show that the large plantation of eucalyptus would strongly influence the watershed hydrological process.The surface runoff depth is 17.5%higher than that of current coniferous forest,while the evapotranspiration is 18.1%lower.The flood peak discharge increases also.It will increase the probability of flood disaster in the watershed.If the existing coniferous forest ecosystem were degraded to grassland,the annual average runoff depth would increase by 24.4%,and the evapotranspiration would decrease by 25.3%in the watershed.It isn t beneficial to the water reservation for the natural watershed.Besides,the replacement of coniferous,broad-leaved and mixed forest has less influence on the hydrological processes,compared with other vegetation types.The research findings provide a reference for the analysis of the laws of temporal and spatial evolution of hydrological processes and their ecological and environmental effects in the context of watershed enviroment change.It has practical significance for the management planning of water resources and ecological and environmental protection in mountainous areas in southern China.