What can 25 years of observing the same watershed teach us about groundwater? Can intensive pumping make groundwater deeper in valleys than on hills? Can decades of depletion be reversed by just a few exceptionally wet years? And how does fertilizer applied at the surface end up contaminating groundwater tens of metres below?

Professor Shekhar Muddu joins host Veena Srinivasan on the Water Data Podcast for a deep dive into the Kabini Critical Zone Observatory and what decades of field measurements have revealed about groundwater, agriculture, pollution and climate.

The conversation traces the evolution of the observatory from paired forested and agricultural catchments to a long-term interdisciplinary experiment studying groundwater levels, geochemistry, soil moisture, evapotranspiration and human water use.

Shekhar and Veena explore how intensive groundwater pumping altered natural groundwater gradients, how farmers responded to declining well yields, and how extreme rainfall events can produce large pulses of recharge. They also discuss research showing very high nitrate concentrations in parts of the aquifer, revealing how modern agricultural pollution can travel rapidly into deep groundwater through fractured hard-rock systems.

The episode also looks at the future of water observation in India, from satellite-based soil-moisture measurements to evapotranspiration monitoring, solar-induced fluorescence, carbon fluxes and the need for long-term environmental observatories.

The Water Data Podcast is a talk show on the science, systems, and stories of water, hosted by Veena Srinivasan.

For all references and further readings related to the episode, visit https://welllabs.org/wdp-sekhar-muddu/

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Recording by Nabina Chakraborty, Vraj Acharya and Nanditha Gogate. Video editing by Srisabari Varaguna Pandian. Graphics and artwork by Aparna Nambiar and Kanishka Goyal. Audio mixing and mastering by Vijay Doiphode. Podcast production and management by Nabina Chakraborty and Pavan Srinath.