How is the Palar River basin revealing India’s groundwater future?

Groundwater is becoming India’s most important and most threatened source of water. In Tamil Nadu’s Palar River basin, an area that once depended on a flowing river but now survives mostly on wells, the future of groundwater is already visible. As the river has dried and rainfall has become more erratic, farmers and households rely almost entirely on aquifers. This shift has brought new problems: rising salinity, chemical contamination, and declining water quality.

A new study on the Palar basin uses chemistry, mapping tools, and artificial intelligence to understand what is happening under the ground. “Hydrogeochemical Insights for Sustainable Irrigation: A Case Study from the Palar River Basin, Tamil Nadu” (Dange, Arumugam, & Vijayaraghavalu, 2025), published in Agricultural Water Management, situates this basin within a broader sustainability discourse.  By analysing 132 groundwater samples, the research reveals how geology, industry, farming practices, and climate pressures are reshaping the basin’s water. The authors construct a multidimensional understanding of irrigation water quality, linking their findings explicitly to the Sustainable Development Goals (SDGs) — notably SDGs 2, 6, 12, and 13. The findings show not only what is changing in the Palar, but also what many parts of India may soon face.

What does mapping the anatomy of groundwater tell us about the Palar basin?

The study undertakes an extensive physicochemical survey of 132 groundwater samples across Gudiyatham, Anicut, and K.V. Kuppam blocks, covering a 37.2 km stretch of the Palar River. Parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), and Sodium Adsorption Ratio (SAR) were measured against national and WHO standards to determine irrigation suitability.

How do equations translate into ecosystems in groundwater science?

The analytical framework integrates Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) with a Fuzzy Inference System (FIS)—a computational model that mimics human decision-making under uncertainty. Unlike conventional Water Quality Indices (WQIs) that offer fixed thresholds, the FIS accommodates overlapping variable ranges and multidimensional interdependencies.

The model classified groundwater samples into excellent, good, average, and unsuitable for irrigation with over 80% accuracy, significantly outperforming single-parameter indices. This approach bridges the epistemological divide between data science and field hydrology, offering a replicable framework for real-time water quality assessment across similar semi-arid basins in India.

What’s really in the water, and why does it matter?

The hydrochemical data reveal silicate weathering as the dominant natural process influencing groundwater chemistry — a typical feature of crystalline aquifers in peninsular India. However, superimposed upon these natural controls are strong anthropogenic signals.

The Sodium Adsorption Ratio (SAR) ranged from 0.3 to 121, exceeding the irrigation safety limit in several locations. Elevated sodium levels degrade soil permeability, leading to reduced crop yields and soil alkalinity. Similarly, high Scaling Index (SIL) and Ryznar Stability Index (RSI) values indicate mineral scaling and corrosion risks in irrigation systems, particularly near the river corridor. These findings reflect a hydrochemical transition from rock-dominated to pollution-dominated regimes, signalling a need for immediate intervention.

Is the Palar basin a mirror to global water crises?

The Palar Basin’s dynamics resonate with global hydrogeochemical patterns observed in the Murray–Darling Basin (Australia), Nile Delta (Egypt), and Yangtze River Delta (China)—regions where over-extraction, evaporation, and poor irrigation management have led to salinisation and groundwater decline.

By applying a fuzzy-logic-based decision framework, this study contributes a methodological innovation of global relevance: a scalable model that can account for both hydrogeological uncertainty and data scarcity. It repositions groundwater research within the climate adaptation and food security agenda, demonstrating that localised groundwater diagnostics are essential instruments for achieving SDGs 2 (Zero Hunger) and 6 (Clean Water and Sanitation).

How do soil, crops, and chemistry intertwine in a thirsty landscape?

The study’s implications for agro-hydrological planning are clear. In areas where groundwater exhibits high SAR and sodium content, the authors recommend salt-tolerant crops—such as sorghum, barley, and cotton—alongside gypsum-based soil amendments and drip irrigation systems. Where water remains low in salinity, high-value horticultural crops like tomatoes and cucumbers can be sustained.

These recommendations align with adaptive irrigation strategies in Gujarat, Punjab, and Haryana, where micro-irrigation and crop rotation have slowed salinity progression. Such practices, when integrated with spatially referenced groundwater monitoring, can create climate-resilient agricultural zones in Tamil Nadu’s semi-arid landscapes.

What are the hidden health risks of heavy metals in groundwater?

The study also identifies heavy metal contamination—notably chromium, cadmium, and iron—in groundwater samples, likely from industrial and tannery effluents. Such contaminants, once absorbed into irrigation water, bioaccumulate in crops and soil, posing chronic cardiovascular and toxicological risks to humans.

In response, the researchers advocate for community-based groundwater monitoring, localised reverse osmosis (RO) plants, and constructed wetlands to treat contaminated sources. These interventions complement the Jal Jeevan Mission’s focus on water safety while integrating environmental governance with public health outcomes.

Can data and AI drive a more sustainable groundwater future?

At the governance level, the Palar study proposes a data-integrated groundwater management framework, combining fuzzy logic modelling with geospatial datasets. The authors outline a fivefold action agenda:

1. Continuous groundwater monitoring through automated loggers and citizen observatories.

2. Integration of water quality maps into district and state irrigation planning.

3. Predictive early-warning systems using AI to identify emerging salinity or contamination hotspots.

4. Circular water management, including effluent reuse and aquifer recharge.

5. Alignment with SDG-linked planning instruments, ensuring institutional accountability.

Such an approach can reorient India’s water governance from reactive crisis management towards preventive aquifer stewardship, linking agricultural productivity with ecological sustainability.

Why does this research matter for India’s water security?

The Palar River Basin is home to more than 659,000 groundwater-dependent residents, making its water security directly synonymous with local livelihood security. The study provides an empirical basis for designing block-level groundwater management frameworks under India’s Atal Bhujal Yojana and PMKSY programmes.

By integrating hydrogeochemical diagnostics with artificial intelligence, this research marks a shift from descriptive hydrogeology to decision-analytic hydro governance. Its implications extend beyond Tamil Nadu: as aquifers across India face declining recharge and rising contamination, the fusion of fuzzy logic, GIS, and PCA-based analysis offers a replicable template for evidence-based irrigation planning.

Ultimately, the study underscores the principle that groundwater sustainability is not a purely technical challenge but an institutional and behavioural one. The Palar Basin, in its struggle to balance human demand with geological limits, exemplifies the broader negotiation India must undertake between growth and ecological restraint.

The Palar basin’s story is not just about one river; it reflects the challenges of groundwater across India. As aquifers become the main source of water for drinking and farming, understanding their chemistry and health is essential. This study shows that data, science, and technology can help identify pollution early, guide crop choices, and protect soils. But lasting change will require more than technical tools.

Better monitoring, stronger regulation, and active community involvement will be critical to protect groundwater from overuse and contamination. The Palar reminds us that aquifers are slow to recharge and quick to degrade. If India wants secure food systems and safe water in the decades ahead, managing groundwater wisely before crises emerge must become a national priority.