云南高原杞麓湖流域的景观格局与水质变化

Relationship Between Landscape Pattern Changes and Water Quality in the Qilu Lake Basin of Yunnan Plateau

由于人类活动日益增强,高原湖泊杞麓湖景观格局和湖泊水质发生较大改变,探究其变化关系可为湖泊生态系统保护和流域管理提供科学参考。采用2005年、2010年和2015年遥感影像的解译结果,结合RS/GIS技术和Pearson相关统计方法,分析了10年间景观格局变化、湖泊水质变化及其相关性。结果表明：（1）2005-2014年杞麓湖水质偏差,其中总氮、高锰酸盐指数、生化需氧量和叶绿素a呈显著增长趋势,氨氮、总磷和透明度波动较大,2015年整体水质有所改善,但仍为劣Ⅴ类水。（2）杞麓湖流域主要景观类型是林地和耕地,占流域总面积的74%以上,10年间建设用地面积增加较快（＋876.42hm^2）,水域（-1 281.42hm^2）和耕地（-794.61hm^2）缩减较多,后5年湖滨湿地大量出现（＋1 432.08hm^2）;景观格局聚集程度增加,异质性略有减弱,破碎化程度降低,多样性和均匀程度变化不大,人类活动对景观格局影响强烈。（3）水田、旱地和建设用地聚集程度增强及破碎化程度降低与氨氮外的其它水质指标呈正相关,水域面积与氨氮和高锰酸盐指数呈负相关,水田与建设用地是杞麓湖水质退化的主要污染源。

Qilu Lake is one of nine plateau lakes in Yunnan Province.In recent years,increased human activity has changed the original landscape pattern and water quality in the Qilu Lake Basin has declined.In this study,we explored the relationship between changes in landscape pattern and water quality using Pearson correlation analysis of landscape pattern indices and water quality parameters.The results provide a scientific reference for ecosystem protection and watershed management.The evolution of landscape patterns in the Qilu Lake basin from 2005 to 2015 were analyzed using GIS and remotely sensed data collected in 2005,2010 and 2015.Water quality parameters（CODMn,BOD5,TN,TP,NH——3-N,Chl-a and SD）were provided by the Yunnan Province Environmental Monitoring Center.Results indicate：（1）Water quality in Qilu Lake was poor during the period 2005-2014.Among the seven water quality parameters,TN,CODMn,BOD5 and Chl-a increased significantly and NH3-N,TP and SD fluctuated widely.While water quality improved in 2015,it did not meet GradeⅤstandards.（2）The primary land uses in Qilu Lake basin are forestland and farmland,together accounting for 76.95%,76.54% and 74.53% of the total area in2005,2010 and 2015.Over the ten-year period,the area of construction lands increased by 876.42 hm^2 and lakeside wetlands by 1432.08 hm^2,while water-covered areas decreased by 1281.42 hm^2 and farmland by794.61 hm^2.The degree of landscape aggregation increased,slightly reducing heterogeneity.There was no obvious change in diversity or uniformity.Human activities had a large impact on land use.（3）The aggregation of paddy field,dry cropland and construction land increased,exhibiting apositive correlation with water quality parameters,except for NH——3-N.Water-covered areas were negatively correlated with NH——3-N and CODMn.Paddy fields and construction lands were the main drivers of water quality deterioration in Qilu Lake and non-point source pollution from paddy fields was the primary pollution source for Qilu Lake.