Analysis of groundwater level dynamic characteristics and influencing factors in Valley Plain of Lhasa City

In this paper, taking Chengguan District of Lhasa City as an example, the dynamic characteristics and influencing factors of groundwater in the valley plain of Lhasa City are analyzed. The intra−year and inter−annual variation characteristics of groundwater level from 1996 to 2015 in Chengguan District are analyzed, and the spatial interpolation of inverse distance weighting method（IDW）is used to obtain the spatial distribution and amplitude of groundwater level. The Pearson correlation analysis method and the Grey correlation method are used to analyze the influencing factors of groundwater level dynamics in Chengguan District and the degree of influence of each factor. The analysis results show that the groundwater level has the distribution characteristics of high in the east and low in the west, high in the middle, and low in the north and south. From 1996 to 2015, the groundwater level decreased year by year, with a decline range of 0.2~3.7 m, and an average annual decline is between 0.01 m and 0.19 m. The groundwater level is jointly affected by precipitation, temperature, extraction and the construction land area. The degree of influence is: the temperature > precipitation> the construction land area > the amount of groundwater extraction.