基于环境同位素的陇东盆地地下水分析

Analysis on Groundwater Based on Environmental Isotopes in the Longdong Basin

目前同位素技术在水文水资源领域应用非常广泛,也取得了较大的成果,研究地下水同位素对于有效开发利用水资源和预测地下水环境的变化具有重要的意义。根据陇东盆地同位素测试结果,分析盆地地下水同位素分布特征,追溯地下水的来源及运移过程。结果发现:陇东盆地地下水均来源于大气降水,地下水循环具有浅层循环与深层循环两种模式。浅层地下水积极参与现代水循环,可更新能力较强,地貌对地下水径流控制作用明显。深层地下水为古地质时期补给形成的,水交替径流缓慢,可更新能力弱,地下水径流受地质构造控制,从向斜两翼向核部汇集在盆地中部排泄于河流基准排泄面。

The Longdong Basin underlying complex aquifers is a large sedimentary basin with arid climate and limited annual precipitation in eastern Gansu Province, and it is rich in mineral resources and one of the important energy bases. As a result the balance of natural ecosystem is frangible, it is essential to get a clear understanding for groundwater so as to estimate and rationally utilize the limited groundwater resources. It is not easy to understand the hydrogeologic conditions by common drilling or other field methods. At present the isotope methods are successfully applied to study the groundwater flow system, and hydrologists have got more information about the groundwater recharge, flow and discharge conditions. Based on the isotope analysis results of the groundwater and river water samples in the Longdong Basin, in this paper the sources and change of groundwater are analyzed. The results show that the water cycle patterns of shallow and deep groundwater are different, there is shallow groundwater in modern water cycle, so the renewable capability is strong, and runoff of shallow groundwater is affected by the geomorphologic conditions; whereas deep groundwater was mainly recharged in ancient geological periods, and the synclinal basin controls the groundwater flow, groundwater converges from the wings to the central part of the basin, and discharges to the datum plane of the lower reaches of a river, the runoff flows slowly, and the renewable capability is poor.