乌兰布和沙漠东南缘湖泊群消涨与驱动因素

Lake fluctuation and driving factors in the Wulanbuhe Desert of China

湖泊是对环境变化响应敏感的地理单元,湖泊消长与响应机制研究对维持区域生态系统稳定具有重要意义。基于1999-2018年Landsat、气象、水文和农业种植面积等多种数据,在ArcGIS平台中利用改进归一化差异水体指数(MNDWI)及目视修正方法提取了乌兰布和沙漠东南缘湖泊群空间信息,运用统计学方法对主要驱动因子与湖泊消涨的关系进行了分析。结果表明:1999-2018年乌兰布和沙漠东南缘大湖泊(面积大于100 hm2)在面积上占优势,小湖泊(面积小于100 hm2)在数量占优势。趋势分析表明大湖泊面积和数量呈显著性减少趋势(相关系数分别为R=0.624>R18,0.01=0.561和R=0.648>R18,0.01=0.561);小湖泊减少趋势不显著。在空间分布格局上,研究区中部是大湖泊稳定分布区,大湖泊数量11~23个,面积2208~4581 hm2。研究区湖泊消长主要受到年实际引黄水量、农田面积和地下水埋深的影响。其中,实际引黄(河)水量影响所有湖泊(P≤0.01),而农田面积和地下水埋深分别对大湖泊(P≤0.01)和小湖泊(P≤0.05)影响显著。用这3个因子分别构建的多元回归模型显示,在大、小湖泊面积和数量预测方面,精度分别达到75.7%和60.5%以上。

The lake is the most sensitive geographical unit to environmental change,and the study on the response mechanism of lake fluctuation is of great significance for ecosystem stability.In this paper,based on Landsat data,meteorological data,hydrological monitoring data and cropland area from 1999 to 2018,the improved normalized differential water index(MNDWI)and visual correction methods were used to extract lake distribution information in the Wulanbuhe Desert by ArcGIS technique,and the relationship between the driving force factors and lake fluctuation was analyzed by statistical method.The results showed that large lakes area(area size more than 100 hm2)and small lakes number(area size less than 100 hm2)were dominant in the southeastern margin of the Wulanbuhe Desert in study period,respectively.The trend analysis showed that the area and number of large lakes had a significant decrease trend(R=0.624>R18,0.01=0.561 and R=0.648>R18,0.01=0.561),and the small lakes was not significant.In terms of lake spatial distribution pattern,the central part of the study area was a sustainable distribution area of large lakes.Typical year analysis indicated that the number of large lakes varied in 11-23,and the area changed between 2208 and 4581 hm2.The lake change was mainly affected by the yearly actual amount of yellow water diversion,cropland area and under groundwater table.Among them,the yearly water diversion have affected all lakes(P≤0.01),while the cropland area and under groundwater table had significant effects on large lakes(P≤0.01)and small lakes(P≤0.05),respectively.The multiple regression model constructed with the above mentioned key factors could predict the changes in the area size and number both of large lakes with an accuracy of over 75.7%and small lakes with an accuracy of over 60.5%.