Dynamics of Shallow Groundwater table and the Factors Impacting It in the Nearshore Vegetable Field of the Erhai Lake

YANG Yanxian; ZHANG Dan; LEI Baokun; LIU Hongbin; ZHAI Limei; MAO Yanting; FENG Guangheng; CHEN Anqiang

doi:10.13522/j.cnki.ggps.2017.12.017

Abstract：Understanding the dynamics of shallow groundwater table in the nearshore vegetable field of the Erhai Lake was essential for regulating groundwater resources and preventing nitrogen and phosphorus leaching.Based on groundwater data measured from June 2014 to May 2016 in the nearshore vegetable field,we analyzed the dy-namics of the groundwater depth and the factors affecting it. The results showed that the shallow groundwater depth at different elevations showed a normal distribution and the average depth of shallow groundwater table was from 25.21 cm to 45.07 cm with variation coefficient of 0.26 to 0.43.The shallow groundwater depth was deeper in the dry season than in the rainy season,and its monthly variation in the rainy reasons differs from that in dry reasons, characterized by a hysteresis.The variation coefficient of the shallow groundwater depth in the rainy season was greater than that in the dry season. The spatial variation of the shallow groundwater depth showed irregular distribution.The water level of the Erhai Lake,rainfall,irrigation,phreatic evaporation and spa-tial variability of soil physical properties were the main factors that affect the shallow groundwater depth in the nearshore vegetable field.There was a good linear correlation between the shallow groundwater water depth at el-evation of 1966 m and the water level of the Erhai Lake(p<0.01).There were also good linear correlations be-tween the shallow groundwater depths in other areas and the rainfall,irrigation(p<0.05).The soil parental materi-al was from river-lacustrine facies deposits into Quaternary red clay away from the Erhai Lake,and the permeabil-ity of different soil genesis were from stronger to weaker.These factors caused shallow groundwater depth was shallower and the smaller change range of water level with the farther away from the Erhai Lake and the higher the altitude.