Groundwater-Surface Water Interaction in the Upper Ganga-Yamuna Interfluve in Northern India: Impact of Two Centuries of Irrigation and Groundwater Use

The Indo-Gangetic Basin (IGB) is currently a global hotspot for groundwater overexploitation. Over the past two centuries, groundwater levels initially rose due to increased recharge from irrigation canals but later declined as extractions for agricultural, municipal, and industrial use intensified. However, the relative impacts of recharge and abstraction sources, such as precipitation, canal leakage, irrigation return flow, and municipal and industrial use, remain unclear, as do the effects on groundwater-surface water interactions and environmental flows. This study quantifies spatio-temporal changes in groundwater recharge and abstraction over the past two centuries and simulates with a groundwater model the effects on groundwater levels and groundwater-surface water interactions in the Upper Ganga-Yamuna interfluve in Northern India. The findings align with previous studies: canal water infiltration after canal construction (>1830) boosted recharge, but increased abstractions have lowered groundwater levels and reduced river discharge since the 1970s. Today, irrigation accounts for the majority of abstractions, with municipal and industrial uses far smaller. From around 2000, abstraction decreased groundwater levels to such extent that local rivers likely shifted from discharging to infiltrating. Groundwater-surface water interactions have weakened, particularly reducing discharge to local rivers. While the Yamuna and Ganges show reduced groundwater exfiltration, they are not (yet) losing. This shift threatens environmental river flows, degrades surface water quality by limiting wastewater dilution, and harms groundwater quality as polluted river water infiltrates, posing risks to both ecosystems and human health.