诺敏河流域土地利用与覆被变化及其对水文过程的影响

流域土地利用/覆被变化及其水文效应是当前全球变化研究的重要内容.为正确认识大兴安岭森林采伐对水文过程的影响,以诺敏河流域为例,在遥感和地理信息系统技术支持下,结合地形图和卫星遥感影像数据,获取1954-2005年诺敏河流域5期土地利用/覆被数据,在GIS空间分析模块下分析诺敏河流域土地利用/覆被变化过程,并探讨土地利用/覆被变化对水文过程的影响.结果表明,近50 a诺敏河流域土地利用方式发生了明显变化,林地和草地分别减少1 940.1 km2和748.99 km2,与林草地的大面积减少相对应,耕地面积增加2 741.7 km2.自1998年实施大兴安岭天然林保护工程以后,林地采伐和耕地开垦速率明显降低；土地利用/覆被变化影响年径流量,林地大规模减少、耕地明显增加的后期土地利用较前期径流量有所增加,且随着降雨的增多,土地利用变化对径流的影响效应随之增强.同一降雨条件下土地利用/覆被变化对径流的影响在生长季具有明显差异.

Land Use/Cover Change and Its Effects on Hydrologic Processes in Nuomin River Basin

Land use/cover change and its effects on hydrologic processes are becoming an important aspect of global change research.In order to understand the effects of deforestation on hydrologic processes in theDaxing'anling area,a five-stage land use/cover date base in the Nuomin River basin since 1954was established based on remote sensing imagery data and topographic map.With GIS spatial analysis tools,the paperanalyzed the land use/cover change characteristics and its effects on hydrologic process.Results indicatedthat land use changed prominently in the Nuomin River basin during the past five decades.Forest and grassland decreased by 1 940.10and 748.99km²,respectively,and in contrast,cropland increased by 2 741.7km².Since the nature forest protection project came into force in the Daxing'anling area in 1998,woodlandreduction and farmland reclamation have showed a declined trend.Land use/cover change had effects on annual runoff and runoff increased during the late land use period with decreased forest and more cropland,andthe impact of land use/cover change on runoff was strengthened in response to increased rainfall.Besides,the effects of land use/cover change on runoff production were characterized by seasonal fluctuation.