诱发滑坡的地下水流系统响应历史与趋势——以甘肃黑方台灌区为例

The response of regional groundwater system to irrigation at Heifangtai terrace, Gansu Province

灌溉的地下水系统响应是黑方台地区灌溉诱发地质灾害研究的基础。黑方台台塬自上而下由黄土、砂砾石和基岩3个含水岩组构成。以对斜坡稳定性影响最大的黄土含水系统为研究对象,分析了灌溉前后水均衡变化,采用数值模拟的方法恢复了引水灌溉引起的地下水流系统演化过程,对不同灌溉量下地下水流系统发展趋势进行了预测。结果表明,黑方台地区长期大量引水灌溉打破了地下水均衡,改变了地下水系统的天然状态,使地下水的分布及其水流系统发生了很大变化,中心部位地下水位44年间上升了至少20m,减少灌溉量至350×104m3/a地下水位将呈下降趋势。研究成果可为黑方台滑坡地质灾害综合治理提供科学依据。

The response of regional groundwater system is the basis for the research on landslides induced by irrigation. The Heifangtai terrace comprises three groundwater units of loess, gravel and sand-mud stone. Taking the loess unit as the study object, which affects the stability of loess slope most, the authors analyzed the changes of water balance in the loess unit before and after irrigation, recovered the evolution of groundwater system induced by irrigation and predicted the development trend of the groundwater system under the condition of different irrigation volumes with the numerical method. The calculated results show that the water balance has been broken and the original groundwater system has been changed after a long term irrigation in this area. The groundwater level in the center of the plateau has increased by 20m in the past 44 years, and it tends to decrease when the volume of irrigation is reduced to 350×104m3/a. The results obtained can provide scientific support for comprehensive prevention and control of geo-hazards in Heifangtai area.