The monsoon-driven river basins are more vulnerable to the flash-floods triggered by intense rainfall activities. Due to the lack of adequate high resolution forecast of real-time hydro-meteorological variables, a reliable forecast of flash floods remains a challenge. One plausible way to generate such a high-resolution forecast of hydro-meteorological variables is to use a coupled atmospheric–hydrologic modelling system. Thus, in this study, a physically-based, fully distributed, multi-scale hydrologic modelling framework, WRF-Hydro with optimized configurations (stand-alone and coupled-mode) is used to simulate the important hydro-meteorological variables like precipitation, runoff, soil moisture, and land surface heat fluxes over Cauvery river basin, India. In stand-alone mode, the model is driven by the high-resolution gridded data from the Global Land Data Assimilation System; while the coupled model is run with the WRF atmospheric model. In this study, the ability of a fully coupled WRF–WRF-Hydro modelling framework , with 3 km grid spacing is used to simulate the hydro-meteorological conditions during an extreme rainfall event (08–09 August 2019). The innermost domain of WRF-Hydro in conjunction with a high resolution hydrological routing grid (300 m) is also utilized, to include the subgrid scale disaggregation–aggregation weighting procedures to generate the land–atmospheric feedbacks on the hydrometeorological variables. The resulting variables have been validated through relevant observations; the overall performance of the coupled WRF-Hydro is shown to be relatively good when compared to the WRF-only simulations.

季风驱动的流域更容易受到强烈降雨活动引发的山洪暴发的影响。由于缺乏对实时水文气象变量的高分辨率预测，对洪水的可靠预测仍然是一个挑战。产生这样高分辨的水文气象变量预报的一种可行方法是使用大气水文模拟系统。因此，在本研究中，使用具有优化配置（独立模式和耦合模式）的基于物理的，完全分布式的多尺度水文建模框架WRF-Hydro来模拟重要的水文气象变量，例如降水，径流，印度的Cauvery流域上空的土壤湿度和地表热通量。在独立模式下，该模型由来自全球土地数据同化系统的高分辨率网格数据驱动。而耦合模型与WRF大气模型一起运行。在这项研究中，具有3 km网格间距的完全耦合WRF-WRF-Hydro建模框架的能力用于模拟极端降雨事件（2019年8月8日至9日）期间的水文气象条件。WRF-Hydro的最内层区域还与高分辨率水文路由网格（300 m）结合使用，包括亚网格规模分解-聚合加权程序，以生成有关水文气象变量的陆地-大气反馈。结果变量已通过相关观察得到验证；