IIT Delhi and IIT Roorkee have found that riverine floods in India are changing over the past 40 years (1970–2010) based on data from >170 monitoring stations across the country.
Key highlights of the study
- Decline in Flood Magnitude: 74% of stations showed decreasing flood magnitude trends whereas 26% showcased increasing trends. Larger catchment experienced reduced flood magnitudes
- Region Specific:-
- West and Central Ganga basin: 17% decline per decade in monsoon floods (due to declining precipitation and soil moisture)
- Narmada basin: Consistent decrease in magnitude of floods(mainly on account of dam construction)
- Marathwada region: River flows are decreasing at 8% during monsoon and 31% in pre-monsoon season
- Region Specific:-
- Rise in Pre-Monsoon Flood Intensity: Malabar Coast (Kerala, Tamil Nadu): Increase of 8% per decade in pre-monsoon flood intensity (due to rising pre-monsoon rainfall). It affects rivers such as Chaliyar, Periyar, Bharathapuzha etc.
- Shift in Flood Timing: Upper Ganga(delayed floods), Central India (earlier floods), Southern India (generally sees later floods)
Implications
- Reservoir operations & water security: Declining floods may mean lower reservoir levels affecting water supply, irrigation and hydropower.
- Overhauling of Flood management system: Increased focus on early warning, green buffers, smart planning, and resilient infrastructure
