长武黄土塬区土地利用变化对潜水补给的影响

通过长武黄土塬区不同土地利用方式下深剖面土壤水分的长期定位监测以及氢氧稳定同位素示踪技术的使用，分析了该区域土地利用变化对地下潜水补给的影响。结果表明:① 降水补给地下水过程中存在着活塞流和优先流两种机制，由活塞流补给的地下水量，以休闲地居高，低产农田次之，最后是高产农田；② 随着该区域农田生产力大幅提升以及大面积农田转换为果园，地下水活塞流补给量逐年减少，加之地下水开采量增加，导致地下水位逐年下降，年均降幅达0.3 m；③ 同位素证据表明，目前长武塬区地下水补给以优先流形式为主。为了实现黄土塬区潜水资源的有效补给与可持续利用，需要合理调控土地利用结构，保持适度生产力水平。

Land use change affects groundwater recharge in the Changwu Loess Tableland of China

Long-term soil water data monitored in deep loess profiles under different land use patterns, combined with the hydrogen and oxygen stable isotopic tracer techniques, were used to investigate the effects of land use change on groundwater recharge in the Changwu Loess Tableland. Results showed that: ① Both piston flow and preferential flow coexisted in the process of groundwater recharge. The land uses, in order of decreasing the groundwater recharge by piston flow, are the fallow land, low-yield filed and high-yield field. ② The increased productivity and large scale conversion of cropland to apple orchards have resulted in reduced groundwater recharge by piston flow, combined with the increased groundwater mining, causing the groundwater table to decline continuously at 0.3 m/a. ③ The isotopic data indicate that preferential flow is currently the main path way for groundwater recharge. In order to achieve effective supply and sustainable utilization of groundwater resources on the Loess Tableland, it is necessary to regulate the land use structure reasonably and maintain an appropriate level of land productivity.