Connectivity of groundwater flow within crystalline-rock aquifers controls the sustainability of abstraction and baseflow to rivers, yet is often poorly constrained at a catchment scale. Here groundwater connectivity in a sheared gneiss aquifer is investigated by studying the intensively abstracted Berambadi catchment (84 km²) in the Cauvery River Basin, southern India, with geological characterisation, aquifer properties testing, hydrograph analysis, hydrochemical tracers and a numerical groundwater flow model. The study indicates a well-connected system, both laterally and vertically, that has evolved with high abstraction from a laterally to a vertically dominated flow system. Likely as a result of shearing, a high degree of lateral connectivity remains at low groundwater levels. Because of their low storage and logarithmic reduction in hydraulic conductivity with depth, crystalline-rock aquifers in environments such as this, with high abstraction and variable seasonal recharge, constitute a highly variable water resource, meaning farmers must adapt to varying water availability. Importantly, this study indicates that abstraction is reducing baseflow to the river, which, if also occurring in other similar catchments, will have implications downstream in the Cauvery River Basin.

结晶岩含水层中地下水流的连通性控制着引流和向河流的基流的可持续性，但在集水区范围内通常受到的约束很有限。在这里，通过研究密集提取的贝拉姆巴迪流域（84 km ²），位于印度南部的Cauvery流域，具有地质特征，含水层特性测试，水文特征分析，水化学示踪剂和地下水数值流模型。研究表明，横向和纵向的连接良好的系统已经从横向到垂直主导的流动系统高度抽象化地发展了。可能由于剪切作用，在地下水位较低时仍保持高度的横向连通性。由于其低储量和水力传导率随深度的对数减小，在这样的环境中具有高提取和季节性补给的结晶岩含水层构成了高度可变的水资源，这意味着农民必须适应变化的水量。重要的是，这项研究表明，抽象化正在减少河流的底流，