Can groundwater development reduce reliance on large scale water transfers?

Abstract:

Inter basin water transfers (IBWTs) provide a way to manage water scarcity in the presence of considerable regional differences in water supply and demands of two basins. Although there are several studies on IBWTs, the impact of groundwater development on management of large-scale water transfers is yet to be explored. Here, we investigate the role of groundwater development in reducing reliance on IBWTs for monsoon dominated basins in Southern India. We evaluate an IBWT scheme, the Inchampalli-Nagarjuna Sagar (INS) project, proposed to transfer water from Godavari river basin (Inchampalli reservoir) to Krishna river basin (Nagarjuna Sagar reservoir). We formulate two variants of a multi-objective decision problem to evaluate the impact of the INS-IBWT megaproject with and without conjunctive use of groundwater. One formulation includes an artificial recharge module coupled to the IBWT surface water balance model (recharge formulation), while the other does not (no-recharge formulation). Artificial recharge in the command area of the recipient reservoir is simulated considering the hydro-geology of the region. Pareto optimal transfer strategies are identified by stochastic optimization with the BORG algorithm considering uncertainties in reservoir inflows and five objectives: reliability, resilience and vulnerability of demand satisfaction, reliability of flood protection and minimum environmental flows. We estimate the range of mean annual demand deficits across all the Pareto optimal strategies as 72-138 Mm³ (380- 490 Mm³) in the recharge (no-recharge) formulation. Thus, an improvement in performance is observed in the presence of artificial recharge when demand deficits are aggregated across donor and recipient basins. However, artificial recharge does not necessarily reduce the reliance on the water transfer. A similar range of annual volumetric transfers (9200-12900 Mm³) is observed for Pareto optimal strategies of the recharge formulation compared to the no-recharge formulation (9400-12700 Mm³). Our analysis indicates that groundwater development may help to efficiently utilize the water transferred from the INS-IBWT but not necessarily reduce reliance on the project for the recipient basin.