密怀顺水源保护区土地利用演化驱动因素分析

密怀顺水源保护区位于北京密云、怀柔、顺义的三区交界处，是北京市第八水厂、怀柔应急水源地所在地。2014年底南水北调进京后，部分盈余水量开始通过潮白河河道回补密怀顺地下水。为保护饮用水源，摸清历史面源污染的潜在风险。通过转移矩阵数学模型，利用ArcGIS方法研究了土地利用时空演化规律，结果表明：（1）土地利用变化强度2015年~2018年是2012年~2015年的5.24倍，耕地、未利用地面积呈现减少趋势，林地、水域和湿地、草地面积呈现增长趋势，建设用地先增后减；（2）2015~2018年林地、水域和湿地、耕地变化率最大，分别为92.15%、67.46%、46.6%；（3）2015年后林地、水域和湿地、草地、未利用地面积呈现净转入趋势，耕地、建设用地面积呈现净转出趋势；（4）最活跃的土地属性转变是耕地转入林地，面积为68.23km2，（5）土地利用变化特点与政策驱动力息息相关，土地利用的演化趋势向着利于饮用水源安全的方向发展。可见研究成果可为水源保护区面源污染防治提供科学依据，对未来进一步研究农业面源对保护区土壤和地下水的环境影响奠定基础。

Study on the Driving factors of land use evolution in The Water conservation area of Mihuaishun

Mihuaishun Water Source Conservation Area is located at the junction of Miyun, Huairou and Shunyi districts, which possess Beijing No 8 Water Plant and Huairou Emergency Water Source. Since the South-North Water Transfer Project in Beijing at the end of 2014, partial surplus water has started to replenish underground water of Mihuaishun through the Chaobai River Channel. In order to protect drinking water sources and find out potential risks of historical non-point source pollution, the ArcGIS and transfer matrix model were used to investigate the spatial and temporal evolution of land use. The research results show that: 1) The intensity of land use change from 2012 to 2015 is 5.24 times than that from 2015 to 2018, and. 2) The rates of forestland, water area, wetland and cultivated land are greatly changed, which are 92.15%, 67.46% and 46.6% respectively. 3) The forestland, water area, wetland, grassland and unused land show a net roll-in trend, while the cultivated and construction areas show a net roll-out trend after 2015.4) 68.23km2 cultivated land is conversed into forestland, which is considered as the most active land attribute change. 5) The characteristics of land use change are closely related to policy driving forces. The research indicates that the cultivated land and unused area are decreasing, while the forestland, water area, wetland and grassland are increasing, and the construction land is first increased but then decreased. And the evolution trend of land use is conductive to the development of safe drinking water sources. It is wished that this thesis could provide scientific basis for prevention and control of non-point source pollution in water conservation areas , and lay a foundation for further studies on the influence of agricultural non-point sources on soil and groundwater environment in the conservation area.