GIS-based analysis and visualization of the groundwater changes in Minqin Oasis

Groundwater depth refers to the distance from the ground surface to the groundwater surface and groundwater level refers to the elevation of the groundwater surface. The changes of groundwater depth and groundwater level are both the most directive reaction to the changes of the groundwater resources. This paper combines the Ordinary Kriging Interpolation method with the techniques from geographic information systems to analyze the dynamic changes of the groundwater depth and the groundwater level in Minqin Oasis in Januarys between 1998 and 2010. The results show that: (1) the groundwater depth is greater in the south while it is less in the north. It has declined year by year and the annual mean decline rate was 0.55m/a. The decline range has been gradually decreasing from the southwest to the northeast and the area with bigger groundwater depth has been becoming bigger and bigger due to the increasing of human activities in the Oasis. (2) The groundwater level is higher in the southwest whereas lower in the northeast and it has been continuously decreasing year by year. Meanwhile, the area of low level region has been gradually expanding from the northeast to the southwest.