洞里萨湖流域土地利用变化与其水质的关联性

为探究洞里萨湖流域土地利用变化对湖泊水质的影响,以MODIS土地覆盖产品（MCD12Q1）、湖泊浊度和营养状态指数为数据源,结合GIS空间分析、Theil-Sen Median趋势分析、Mann-Kendall检验和相关性分析等方法,系统研究该流域近20年土地利用与湖泊水质的时空变化特征及两者间的关联性。结果表明：洞里萨湖流域土地利用以林地显著减少（P<0.01）和草地、耕地显著增加（P<0.01）为主要特征,年均变化率分别达到了流域总面积的-1.13%、0.8%和0.35%;相应地,湖泊浊度和营养状态指数亦为上升趋势,但未通过显著性检验。研究时段内,湖泊浊度与林地强负相关（r=-0.65）,与草地、耕地和建设用地强正相关,相关系数分别为0.61、0.74、0.72,与湿地弱正相关（r=0.35）;然而,湖泊营养状态指数仅与湿地弱负相关（r=-0.31）。研究结论为认识洞里萨湖水质变化的驱动因子与流域管理提供科学参考。

Correlation between land use change and water quality in Tonle Sap Lake basin

In order to explore the impact of land use change on lake water quality in Tonle Sap Lake basin, the methods of GIS spatial analysis, Theil-Sen Median trend analysis, Mann-Kendall test and correlation analysis were used to systematically investigate the spatio-temporal variation characteristics and the correlation of land use and lake water quality in recent 20 years based on MODIS land cover products(MCD12Q1), lake turbidity and nutrient state index data. The results showed that land use in the Tonle Sap Lake basin was mainly characterized by a significant decrease in forest land (P<0.01) and a significant increase in grassland and cropland (P<0.01), with the average annual change rates reaching -1.13%, 0.8% and 0.35% of the total basin area, respectively; meanwhile, the lake turbidity and nutrient status index showed an upward trend, but did not pass the significance test. During the study period, lake turbidity was strongly negatively correlated with forest land (r=-0.65), strongly positively correlated with grassland, cropland, and construction land, with correlation coefficients of 0.61, 0.74, and 0.72, respectively. It was also weakly positively correlated with wetland (r=0.35). However, lake trophic state index was only weakly negatively correlated with wetland (r=-0.31). It is concluded that the above conclusions provide scientific references for understanding the driving factors of water quality changes in Tonle Sap Lake and basin management.