河套灌区解放闸灌域植被指数与地下水埋深的定量关系

干旱荒漠地区地下水补给是地表植被水分消耗的主要补给源,地下水埋深与植被指数(NDVI)关系密切。针对植被指数与地下水埋深响应关系研究的不足,分析了基于河套灌区解放闸灌域植被指数(NDVI)与地下水埋深(H)的定量关系。采用2016年3—9月的10个时相的landsat8遥感影像数据与同时期的57眼地下水埋深观测数据,经NDVI遥感提取与地下水埋深(H)的地统计分析,建立NDVI与H的时空相关关系,并做显著性检验与密切程度的划分,进一步分析不同地下水埋深分区下H与NDVI的关系。结果表明:NDVI与地下水埋深(H)存在显著线性关系,二者的密切程度以中度和高度相关为主,负相关区域在地下水浅埋区居多,正相关区域在地下水深埋区居多。从空间上看,具有统计学意义的线性关系约占灌域总面积的40%。当H≤2.5 m时,不同的埋深分区对灌域的NDVI均值的影响为埋深(H)越小,NDVI均值越大,呈负相关关系变化;当H>2.5 m时,NDVI均值较大,地下水不再对作物生长进行水分补给,此时NDVI均值的增大与埋深(H)分区的变化关系不大。从空间上进行NDVI与地下水埋深(H)的点对点的相关性分析,增强了二者相关性的空间可视性,为灌区灌溉管理提供理论支撑,有助于节水增产措施的深入规划与落实。

Study on the Quantitative Relationship Between Vegetation Index and Groundwater Depth in Jiefangzha Irrigation Area in the Hetao Irrigation District

Groundwater recharge is the main source of water replenishment of surface vegetation in the arid desert areas,and the depth of groundwater is closely related to the vegetation index NDVI.In view of the shortcomings of the research on the relationship between NDVI and groundwater depth change,this paper carried out a quantitative relationship between NDVI and groundwater depth(H)based on the Jiefangzha irrigation area in the Hetao Irrigation District.Using ten landsat8 remote sensing image data from March 2016 to the end of September 2016 and 57 groundwater observation data in the same period,the spatial and temporal dynamics of NDVI and groundwater depth(H)were obtained by geostatistical analysis.On this basis,the spatial and temporal correlation between NDVI and H was established through ArcGIS,and the significance test and the degree of closeness were divided.The quantitative relationship between H and NDVI in different groundwater depth zones was further analyzed.It was concluded that there was a significant linear relationship between NDVI and H.The close degree of NDVI and H was mainly moderate and high correlation.The negative correlation area was concentrated in the shallow groundwater area,and the positive correlation area was concentrated in the deep groundwater area.In terms of space,the linear relationship with statistical significance accounted for about 40%of the total irrigation area.When H≤2.5 m,the influence of different groundwater depth zones on NDVI mean value showed a negative correlation change;while when H>2.5 m,the mean value of NDVI was larger,and the groundwater did not supply water for crop growth.Therefore,the increase of NDVI mean value had little relationship with the change of H division.Carrying out the point-to-point correlation analysis of NDVI and H in space could enhance the spatial visibility of the correlation between the two,provide theoretical support for irrigation management in irrigation districts,and contribute to the in-depth planning and implementation of water-saving and production-increasing measures.