典型岩溶农业区地下水质与土地利用变化分析——以云南小江流域为例

The Groundwater Quality and Land Use Change in a Typical Karst Agricultural Region: A Case Study of Xiaojiang Watershed, Yunnan

以云南省泸西县小江典型岩溶农业流域为研究单元,利用1982和2004的地下水质数据及1982的航片和2004年的TM影像,在GIS支持下,研究其20年来的地下水质的时空变化及原因。结果表明:20年来流域地下水质在时间、空间分布上均发生较大的变化;流域耕地扩张和大量化肥、农药使用带来的非点源污染,造成地下水中的NH+4、SO24-、NO-3、NO-2、Cl-离子含量及pH值、总硬度、总碱度明显升高并超标,而林地减少或林地质量的下降,土地发生石漠化时,地下水中的Ca2+、HCO3-浓度明显降低,同时,地下水各指标的空间变化与土地利用空间格局的变化表现出动态一致性。

The present study analyzed the temporal and spatial changes of groundwater quality from 1982 to 2004 in Xiaojiang watershed, Yunnan, Southwest China. The results indicate： （1） There were obvious temporal and spatial changes of groundwater quality in Xiaojing ＋ watershed from 1982 to 2004. The total hardness, total alkalinity, pH, Mg^2＋, NH4^＋, SO4^2-, Cl^-, NO3^- and NO2^- of the groundwater increased significantly, but the Ca^2＋ and HCO3^- showed an obvious declining trend during the past 20 years in Xiaojiang watershed. Furthermore, the concentrations of NH4^＋, NO3^- and NO2^- of groundwater exceeded the drinking water standards in 2004. （2） The total land transformed covers 610.12 km^2, of which 134.29 km^2 of forestland were transformed into cultivated land, and 210 km^2 of unused land was transformed into cultivated land, and the construction land increased by 71.8% during the past 20 years in Xiaojiang watershed. （3） The groundwater quality change is related to the non-point pollution of massive use of fertilizers and pesticides due to the expansion of cultivated land and the deterioration of eco-environment bought by the worsening of forestland quality. As forestland and unused land transformed into cultivated land, the total hardness, total alkalinity, pH, and the concentrations of NH4^＋, SO4^2-, NO3^-, NO2^-, and Cl^- in the groundwater increased significantly, but the concentrations of Ca^2＋ and HCO3^- in the groundwater declined obviously.