The recent floods in Nepal have raised concerns in India, but it's not just about the water flowing downstream. The relationship between these two countries is more complex than that. Nepal's rivers, which drain into India and the Ganges, can cause floods in India, but the severity of these floods depends on various factors on both sides of the border.
One of the main misconceptions is that Nepal 'releases' water into India, but this is not accurate. Nepal has limited large reservoirs, and its main storage dam, Kulekhani, holds a small volume of water. The Kosi and Gandak barrages are operated by India, and the flooding is primarily caused by rainfall in Nepal, not by any intentional release of water.
However, Nepal's rainfall plays a significant role in determining the timing and size of flood peaks reaching India. The Kosi disaster in 2008 is a notable example. Despite the river carrying less water than the embankment's capacity, the catastrophe was caused by the embankment's failure, not an exceptional flood. This highlights the importance of structural integrity and maintenance of Indian embankments.
India's Central Water Commission and Nepal's Department of Hydrology and Meteorology share real-time rainfall and river-level data, which is crucial for flood forecasts. However, there are gaps in monitoring stations, especially in the fastest-flowing Chure catchments, and a lack of a shared forecasting model between the two countries.
The real concern for India lies in the Himalayas. The recent Nepal disaster is similar to other catastrophic events in India, such as the Chamoli and Dharali disasters. These events are not conventional floods but rather the result of intense rain, melting ice, and sediment mixing, creating a high-energy slurry that can destroy everything in its path.
Climate change is exacerbating these issues. Extreme rainfall is increasing, and the region is warming faster than the global average. This leads to more moisture in the atmosphere and heavier monsoon bursts. High-mountain hazards, such as glacial lake outbursts and rock-ice avalanches, are also on the rise, producing faster and more debris-laden floods that are challenging to predict.
The consequences of these events are far-reaching. More extreme events mean more landslides and sediment in rivers, raising riverbeds and reducing channel capacity on both sides of the border. India's exposure to these hazards is significant, and the need for better shared data, forecasting, and river management is crucial to mitigate the risks and protect both countries from the devastating impacts of these natural disasters.
