纸坊沟流域水体氢氧同位素特征及其水量交换研究

Characteristics of hydrogen and oxygen isotopes and water exchange in the Zhifanggou watershed

以安塞县纸坊沟小流域为研究对象,通过对2016年6月—2017年5月降水、地下水和沟头、上游、中游、下游的地表径流氢氧同位素特征分析,研究黄土高原丘陵区小流域地下水补给与排泄的时空特征,为该区域地下水资源的合理利用提供依据。研究结果表明:降水氢氧同位素变异系数较高,具有明显的雨量效应、温度效应与季节效应。地表径流和地下水对温度的响应较好。6—11月降水补给地表径流过程中,因蒸发损失约为37%,补给地下水过程的损失为54%。流域不同部位的降水和地表径流对地下水的补给相似,地下水排泄比例从沟头到下游逐渐减小。地下水的补给与排泄也具有明显的季节特征,6月—翌年5月,降水和地表径流对地下水的补给排序分别为:夏季>秋季>冬季和冬季>秋季>夏季,春季无明显的补给现象。地下水对径流的排泄比例冬季最高,夏季最低。降水和径流对地下水的年补给为26.89%和73.11%。地下水中约有88%的水源于夏半年(6—9月)降水的补给,12%的水源于冬半年(10月—翌年5月)。

To study the spatial and temporal characteristics of groundwater recharge and discharge of small watersheds in hilly regions in the loess plateau,the Zhifanggou watershed is taken as the research object.The hydrogen and oxygen isotopes of groundwater,precipitation and surface runoff in the gully head,upper,middle and lower reaches from June 2016 to May 2017 are analyzed.They may provide a basis for rational utilization of groundwater resources in this area.The results show that the variation coefficients of hydrogen and oxygen isotopes in precipitation are the highest,and they have obvious rainfall effect,temperature effect and seasonal effect.Surface runoff and groundwater have a better response to temperature.From June to November,the evaporation loss is about 37%during the recharge process from precipitation to runoff and 54%during the recharge process to groundwater.The groundwater recharge from precipitation and runoff in different parts of the watershed are similar.The discharge proportion of groundwater decreases gradually from the gully head to downstream.The groundwater recharge and discharge also have obvious seasonal characteristics.From June to May in the following year,the groundwater recharge proportion from precipitation and runoff are:summer>autumn>winter and winter>autumn>summer,respectively.There is no obvious recharge in spring.The proportion of groundwater discharge is the highest in winter and lowest in summer.The average annual recharge proportion from precipitation and runoff is 26.89%and 73.11%,respectively.About 88%of groundwater originates from the recharge of precipitation in the summer months(June to September),and 12%from the the winter months(October to May in the following year).