It is estimated that 251 km3 of groundwater is abstracted per year in India mainly for irrigation purposes. In areas of Rajasthan, Punjab, and Haryana, groundwater levels are being depleted at a rate of 17.7 km3/year.
In such context, managed aquifer recharge (MAR) combined with rainwater harvesting (RWH) is considered as a sustainable water management solution. This approach helps to replenish aquifers and thus facilitates water storage for later use during dry seasons, high demand periods or environmental needs.
MAR structures are simple and inexpensive to deploy: percolation ponds, check dams or more innovative structures such as sand dams are currently utilized for RWH purposes worldwide.
Nevertheless, sound knowledge of their impact on groundwater quality during RWH at the local scale is required and special attention must be paid to both ecological and human risks.
Hence, our research focuses on the attenuation of the aforementioned issues by acquiring field data and laboratory evidence as well as developing simulation models that will inform a step change in the design, location and operation of RWH structures contributing to MAR.
Rajasthan abstracts 37% more groundwater which is second highest rate than is being recharged. Additionally, the state is severely affected by geogenic fluoride contamination (91% districts affected). Thus, the use of RWH structures seems to be a sensible approach to improve both the budget and the quality of groundwater. One of the barriers to a wider implementation include a true assessment of the impact of RWH on groundwater quality at a local scale and the potential environmental and health risks associated with this practice.
The aim of the project is to assess the impact of rainwater used for MAR on groundwater quality and more specifically understand how DOM present in rainwater affects fluoride and other pollutant levels, thereby improving MAR structure design and management practices in selected sites of Rajasthan, India.
Through a comprehensive surface water and groundwater quality monitoring programme focussing on both traditional and emerging MAR technologies, the specific objectives of the project in order to narrow the above knowledge gap are:
1. Evaluate water level and quality at three selected MAR sites in Rajasthan;
2. Assess the proportion of recharged groundwater attributable to MAR systems at selected sites;
3. Investigate the consequences of recharging aquifers with rainwater on the fate and transport of pollutants into aquifers, and understand the role of rainwater DOM levels in remediating fluoride and other groundwater contaminants;
4. Develop analytical protocols to facilitate the detection of micropollutants in water bodies;
5. Understand the interactions of local users with the MAR structure and also their role in water management.