Impact assessment of long-term high-volume abstraction of groundwater from Palla floodplain aquifers of Delhi, India

Abstract

The global demand for freshwater resources has universally stressed the groundwater system. This is particularly seen in urban areas like the National Capital Territory (NCT), Delhi where extreme disturbance in the natural flow conditions may result in a variety of complex hydrological crises. To address the issues of uneven water distribution in NCT-Delhi, a detailed assessment was undertaken to formulate a holistic approach to efficiently utilize natural water in the late 1990s and early 2000s, leading to the development of the Palla well field, which has been deemed successful on the water supply front. However, its hydrogeological impact assessment was not fully reviewed until now.In this context, the study presented here aims to assess the impact of the long-term pumping from Palla well field tube wells on the physical and chemical attributes of the hydrogeological system. The experimental investigations revealed that the aquifers have high potential, and can achieve dynamic equilibrium relatively faster, thereby showing resilience to the drastic effects of prolonged pumping. Furthermore, the isotopic signatures revealed varying impacts of recharge associated with given hydrological settings.Additionally, the XRD and SEM-EDS analyses indicate that the sediment-groundwater interaction does not primarily control the major ion chemistry in the younger alluvium. However, iron enrichment in a few groundwater samples was supposedly observed to be a product of the chemical weathering of iron oxides. Overall, the multifaceted investigation provided evidence that there is no major detrimental impact on the groundwater system from the prolonged pumping in the Palla wellfield.