陕西省乾县地下水位动态变化特征分析

Groundwater Table Dynamics in Qianxian County of Shaanxi Province

依据渭北高塬与关中平原过渡地带的陕西省乾县近16 a地下水位埋深监测资料,结合研究区数字高程模型(DEM)反映的地貌和水系分布状况,选取7口地下水位监测井,对乾县城区、羊毛湾灌区和宝鸡峡灌区地下水位年际和年内动态变化特征进行了分析。结果表明,乾县城区近10 a地下水位以0.31 m/a的速度上升;羊毛湾灌区和宝鸡峡灌区近16 a地下水位均呈下降趋势,并且前者下降幅度大于后者;降水量偏多使得水库水位高于其附近地下水位,距离水库近的地区,地下水位受水库补给和降雨入渗补给双重作用迅速上升;距离水库远的地方,地下水位主要受降雨入渗补给,地下水位上升具有滞后性。灌区地下水位具有在2月和10月左右达到高水位,7月降至低水位的特征。实施节水和井渠结合灌溉是保证乾县地下水资源可持续利用的有效途径。

Inter-annual and seasonal characteristics of groundwater table fluctuations in the urban area of Qianxian County,Yangmaowan irrigation area,and Baojixia irrigation area were analyzed based on the groundwater table data collected from seven monitoring wells between 1992 and 2007,along with DEM which reflects the topography and drainage system distribution of the study area.The study area is located in the transition zone from the North Weihe to Guangzhong region.The results indicate that the groundwater table in the urban area of Qianxian County rose at a rate of 0.31 m/a during the study period.However,the groundwater tables in Yangmaowan and Baojiaxia irrigation areas were declining in the past sixteen years;the groundwater table of Yangmaowan irrigation area declined faster than that of Baojiaxia irrigation area.In wet years,the groundwater tables of the wells that is close to reservoirs rose quickly due to the combined effects of both reservoir recharge and rainfall infiltration.On the contrary,the groundwater tables of the wells that is far from reservoirs rose more slowly as rainfall infiltration was the only recharging source.The irrigation areas had the relatively higher groundwater tables in February and October and the lower ground-water tables in July.Combination of channel and well irrigation is suggested for the sustainable use of groundwater resources in Qianxian County.