Hydrological linkages between different water resources from two contrasting ecosystems of western peninsular India: a stable isotope perspective

Water scarcity is a leading concern in both developing and developed nations. Coping with water scarcity requires an understanding of various hydrological processes that act upon precipitation, surface and groundwater at a local scale. We measured isotopic signatures of several water samples from two distinct ecosystems, i.e. tropical savanna in the West and the warm semi-arid region in the East lying across the Western Ghats mountain range, India, to understand the hydrological processes. The results show that the hydrogeological conditions strongly influence the isotopic characteristics of water of different resources, governed by different hydrological processes, even at close spatial scales. Based on the local evaporation lines of different water resources within a particular ecosystem, it is inferred that the water resources are well linked at one site, but have diverse connectivity at the other site. Further, the isotopic signatures of all the water resources are systematically affected by the monsoon precipitation. In addition, anomalously depleted isotopic signatures are observed during known hailstorm events. This may provide a means to trace their signature in the existing water resources.水资源短缺是发展中国家与发达国家共同面临的首要环境关切。应对水资源短缺，需明晰局地尺度下作用于降水、地表水与地下水的各类水文过程。本研究采集了印度西高止山脉沿线两处典型生态系统——西部热带稀树草原与东部暖半干旱区域的多组水样，测定其同位素特征（Isotopic Signatures），以此解析相关水文过程。研究结果表明，即便在空间尺度相近的区域，水文地质条件（Hydrogeological Conditions）也会通过不同水文过程显著影响不同水体的同位素特征。基于特定生态系统内不同水体的局地蒸发线（Evaporation Lines），可推断出其中一处点位的各类水体间连通性良好，而另一处点位的水体连通性则存在显著差异。此外，所有水体的同位素特征均受季风降水的系统性调控。进一步观测发现，在已知冰雹事件期间，水样呈现异常贫化的同位素特征，该现象或可为追踪现有水体中的冰雹信号提供可行途径。