Impact of groundwater on floods in Peninsular India

The critical role of antecedent wetness conditions of unsaturated zones in modulating floods is widely recognised. However groundwater from deeper saturated zones is often overlooked despite its significant role in storm runoff generation. A new study from IISc reveals the importance of groundwater in shaping river floods in Peninsular India.

Shailza Sharma and PP Mujumdar from the Department of Civil Engineering analysed streamflow data from 70 catchments in Peninsular India to study the relationship between flood magnitudes and flood drivers such as extreme rainfall, soil moisture and groundwater. The results suggest that flood magnitudes are more strongly correlated with groundwater compared to the other two flood drivers.

They observed that groundwater runoff into rivers had a stronger influence on floods, compared to extreme rainfall and soil moisture, over short time scales. Over long time scales, rainfall appears to be the driving factor for flood size, as it affects both soil moisture and groundwater levels.

The authors examined the impact of reservoirs to understand the influence of flow regulations on the flood characteristics such as flood peak, volume and duration. Reservoir regulation has a positive effect by reducing the flood severity in Peninsular India. A reduction in flood peak and volume is achieved due to retention of water in the reservoir and by releasing this excess water over longer durations.

The study has immediate implications for river flood management in Peninsular India. In addition, the observation that water stored in deeper saturated zone contributes to river floods is novel and holds significant importance for future flood-related studies across the globe.


Sharma S, Mujumdar PP, Baseflow significantly contributes to river floods in Peninsular India, Scientific Reports (2024).