洞庭湖区土地利用变化对地表产流的影响分析

利用20世纪80年代末期和90年代末期获取的陆地资源卫星图像，通过GIS分析方法，对洞庭湖区近10年的土地利用／覆盖变化进行了统计分析。并以1996年7月日降雨资料分别计算了1989年和1999年土地利用状况下区域的产水量。结果表明：洞庭湖区10年间土地利用变化的主要趋势是耕地面积减少和建设用地、水域面积的增加。土地利用的主要转化方式有水田转化为建设用地、水田转化为水域、林地转化为建设用地以及旱地转化为建设用地。同样的降雨条件下，洞庭湖区1999年下垫面状况下的产水量比1989年多206×105 m3，建设用地面积的增加是这一时期产水量增加的主要原因。土地利用的变化影响汛期产水量和汇流速度，加强洪泛区的土地管理，合理控制调整土地利用状况是减轻洪涝灾害威胁的有效手段。

IMPACT OF LAND USE CHANGE ON RUNOFF-YIELD OF DONGTING-LAKE AREA

Based on the Landsat TM and ETM data acquired at the end of 1980's and 1990's respectively, the authors analyzed the characteristics of land use/cover changes in the Dong ting Lake area through GIS analytical method. Runoff in 1989 and 1999 was calculated using rainfall pattern in July of 1996. The results show that the characteristics of land use change in Dong ting lake area are reflected in the decrease of the cultivated land and the increase of construction land and the water area . The main conversion of land use include four types: paddy field converted to built up areas and water, the area of forest transformed to built up areas and dry land area converted to construction land. Compared to 1989,runoff increased by 206×105 m3 in 1999 if 1996 precipitation was used. The increase of the construction land is the main reason that runoff increases in this period. Land use change influenced the runoff and confluence process in flood season. To strengthen the land management in flood area and the rational control and adjustment of land use status will lighten the threat of flood disaster.