Controlling floods and droughts through underground storage: from concept to pilot implementation in the Ganges River Basin.
Floods and droughts, along with over-exploitation of groundwater, are major issues of concern across much of the developed and developing world. This report presents an approach - referred to as 'Underground Taming of Floods for Irrigation' (UTFI) - for tackling these challenges in a novel and integrated manner. This approach involves interventions at the river basin scale to strategically recharge aquifers upstream during periods of high flow, thereby preventing local and downstream flooding and simultaneously providing additional groundwater for irrigation during the dry season for livelihood improvement. The three key stages and risks to be addressed in moving from the concept stage to mainstream implementation of UTFI are explained. An analysis of the Ganges River Basin indicates that the prospects for UTFI are high, with 68% of the inner region of the basin having high or very high suitability. Based on a hydrologic analysis of the Ramganga sub-basin, along with tentative estimates of recharge performance based on surface and subsurface recharge methods, the anticipated land area required to store and capture excess floodwater and reduce peak flows are defined. The economic benefits to local agriculture and the wider public benefits from flood reduction are substantial, and warrant the upfront investments and maintenance. After a detailed site selection and consultation process, a suitable site was selected in western Uttar Pradesh where a village pond was retrofitted with recharge wells and associated infrastructure to draw monsoon flows from a nearby flood-prone river. This pilot trial serves as both a scientific experiment and practical demonstration. If the trial and the UTFI approach, in general, can be technically, economically, socially and institutionally verified then there is enormous potential to apply the approach to help decision makers when planning investments in climate change adaption/mitigation and disaster risk reduction.