For decades, Pakistan's water debate has revolved around dams, canals and reservoirs. Every drought renews calls for new storage projects, while every flood revives demands for better infrastructure. These are important conversations, but they often overlook a more fundamental question: how well do we actually understand the water beneath our feet?

Groundwater now supplies nearly two-thirds of Pakistan's drinking water and irrigates much of the country's agricultural land. Yet in many parts of the country, we still do not know with sufficient certainty where this water originates, how quickly aquifers are replenished, how old the water is, or whether current extraction rates are sustainable. We measure what we can see—river flows, rainfall and reservoir levels, but much of Pakistan's most valuable water resource remains hidden underground.

This invisible resource is under growing pressure. Farmers across Punjab continue to drill deeper tube wells to sustain agricultural production. In Balochistan, centuries-old karez systems are disappearing as groundwater levels decline. Karachi struggles with chronic water shortages while seawater gradually intrudes into coastal aquifers. Climate change is altering snowfall, glacier melt and rainfall patterns across the Indus Basin, introducing uncertainties that traditional water management approaches were never designed to address.

The challenge is no longer simply one of water scarcity. It is increasingly a crisis of understanding. Fortunately, scientific advances are opening new possibilities. One of the most promising developments is the integration of artificial intelligence (AI) with isotope hydrology, an area of research that has recently received significant international attention through a new initiative of the International Atomic Energy Agency (IAEA). While the technology itself is sophisticated, its central objective is remarkably simple: helping countries understand their water resources more accurately so they can make better decisions.

The mention of nuclear science often evokes images of reactors or radiation, but one of its most valuable peaceful applications lies in understanding water. Isotope hydrology uses naturally occurring isotopes—different forms of hydrogen and oxygen present in water molecules as scientific tracers. These isotopic signatures function much like fingerprints, revealing where water came from, how long it has remained underground, how different water sources mix, and whether groundwater is being replenished or merely depleted. Such information is impossible to obtain........

© The Friday Times