Flash floods rising, new hotspots emerging across India: IIT study

Time of India

5 hours ago

Dehradun: A new study by researchers at IIT Gandhinagar has warned that flash floods – sudden, high-intensity events triggered by extreme rainfall – are becoming more frequent and severe across India.
Titled 'Drivers of Flash Floods in the Indian Subcontinental River Basins', the study documents the emergence of flash floods in regions previously considered low-risk.
The study points out that semi-arid zones in central India, where flash floods were uncommon, are now seeing more such events due to rising high-intensity rainfall. The western Himalayas face added risk from cloudbursts and snowmelt, which often trigger localised floods, debris flows, and landslides, the study adds.
Vulnerable river basins include the Ganga, Brahmaputra, and Godavari, with new risks emerging along the southeast coast during the northeast monsoon and in Andhra Pradesh during the pre-monsoon season.
Notably, earlier this week, heavy rainfall had triggered flash floods that wreaked havoc in parts of Madhya Pradesh. Several areas in Chhatarpur village were completely submerged as rivers and canals overflowed.
More than a dozen people had to be rescued from the affected regions.
The study also highlights an uptick in intense, short-duration rainfall across peninsular and western India, as well as the lower Himalayas -- trends linked to a warming climate. Even areas with historically low rainfall are now at risk, as dry soils increasingly repel water, converting moderate rain into dangerous runoff,the study says, adding that this shift necessitates the need for regular updates to flood risk maps.
The study noted that India sees around 10,000 flash floods annually, affecting over 90 million hectares of land, citing data from the National Disaster Management Authority (NDMA).
The Himalayas, west coast, and central India have emerged as key hotspots for such events, the study says. In the Himalayas, steep terrain and dense drainage systems are intensifying the threat, while central India and the Western Ghats face high flashiness – a rapid streamflow response to rainfall – exacerbated by low soil moisture.
The researchers found that nearly 75% of flash floods result from extreme rainfall coupled with saturated or dry soils that limit absorption, causing rapid runoff. The remaining 25% stem from short, intense downpours, often under six hours, that can overwhelm even well-drained areas.
The researchers called for the integration of geomorphological and real-time hydrological data to strengthen flash flood forecasting.
Sub-basin-level assessments, they noted, are critical for early warning systems, especially in hilly regions. The findings point to an urgent need for climate-resilient infrastructure, better land-use planning, and robust disaster management, they added.
"The findings have significant implications for flash flood management in India. The study highlights the need for region-specific adaptation strategies tailored to local topography and antecedent basin conditions, as not all extreme rainfall events result in flash floods. Recognising potential new flash flood hotspots is crucial for urban planning and infrastructure resilience in a changing climate," said Vimal Mishra, one of the authors.