India witness floods during the summer monsoon (June–September) that disproportionately affect the socioeconomic well-being of millions of people. Nonstructural measures such as flood early warning systems play a crucial role in mitigating the impacts; however, these require a proper understanding of flood drivers. The drivers of floods in the Indian river basins have not been examined for the observed and projected future climate. Here using a novel framework, we examine antecedent moisture conditions and precipitation characteristics before high flow events. We estimate the probability of occurrence of flood drivers and their association with peak flood magnitude under the observed and projected future climate in Indian river basins. Multiday precipitation, a proxy to heavy precipitation on wet soil conditions, was found as the predominant flood driver in the observed and projected future climate. We show that multiday precipitation is more prominent driver than extreme soil moisture conditions in larger rivers basins while extreme precipitation drives floods in smaller river basins. The frequency of major drivers of floods is projected to rise in the future, which may pose a greater risk to agriculture and infrastructure under the warming climate.

中文翻译：

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多日降水是印度河流域洪水的主要驱动因素

印度在夏季季风（6 月至 9 月）期间发生了洪水，严重影响了数百万人的社会经济福祉。洪水预警系统等非结构性措施在减轻影响方面发挥着至关重要的作用；但是，这些都需要正确了解洪水驱动因素。印度河流域洪水的驱动因素尚未针对观测和预测的未来气候进行检查。在这里，我们使用一个新的框架，检查高流量事件之前的前期水分条件和降水特征。我们估计了在印度河流域观测和预测的未来气候下洪水驱动因素的发生概率及其与洪水峰值的关系。多日降水，代表潮湿土壤条件下的强降水，在观测和预测的未来气候中，发现它是主要的洪水驱动因素。我们表明，在较大的流域，多日降水比极端土壤湿度条件更显着，而极端降水在较小的流域引发洪水。预计未来洪水主要驱动因素的频率将上升，这可能在气候变暖的情况下对农业和基础设施构成更大的风险。