Assessing the hydrological mechanisms and impacts on groundwater of the 2023 flooding in Himachal Pradesh and Punjab

Following severe and successive flooding in Himachal Pradesh (HP) and Punjab in July and August 2023, the British Geological Survey (BGS), in partnership with the National Institute of Hydrology (NIH) Roorkee and the Indian Institute of Technology (IIT) Mandi, undertook a study to investigate flood mechanisms in the upland areas of HP and the impacts on downstream groundwater in Punjab. The aim of this project was to constrain the scale of the extreme events that occurred in HP and Punjab during the 2023 monsoon and to assess their cumulative impact on groundwater recharge and contamination. The objectives were: • characterise flood dynamics, cumulative impacts of persistent rain and the role of dams during flooding in the mountains (HP) and plains (Punjab) • quantify the impacts of floods on groundwater levels and recharge in Punjab, and relate this to upstream and downstream flood characteristics • quantify flood impacts on groundwater quality in Punjab