Addressing Salinity Ingress In Coastal Aquifers: Lessons From Odisha

Coastal aquifers support drinking water, farming, fisheries, industry and ecosystems, yet they are vulnerable to salinity ingress when freshwater pressure falls below seawater pressure. In Odisha, this risk is shaped by a long Bay of Bengal coastline, low-lying deltaic terrain, cyclones, tidal channels, intensive irrigation and growing settlements. Saltwater can move inland through porous sediments, estuaries, abandoned wells and poorly managed pumping systems, reducing the usefulness of groundwater even when water remains available in large quantities.

The experience of Odisha offers practical lessons for Australia. Coastal communities from Perth and Adelaide to Queensland’s fast-growing shoreline also depend on groundwater and face pressure from population growth, horticulture, tourism and climate variability. The National Project on Aquifer Management, operated by the Central Ground Water Board, provides a useful framework for combining aquifer mapping, water-quality assessment, monitoring and community-based management.

Why Coastal Aquifers Become Saline

Fresh groundwater normally forms a hydraulic barrier against seawater. Rainfall infiltrates the ground, recharges the aquifer and creates a freshwater head that pushes seaward. Excessive abstraction lowers that head, allowing seawater to migrate inland or upward into freshwater-bearing layers. The same effect can occur when recharge declines because of drought, hard surfaces, drainage changes or the loss of wetlands.

Odisha’s coastal plain contains unconsolidated sands, silts and clay layers deposited by rivers. These materials vary greatly over short distances. A clay layer may protect a deeper aquifer in one village, while a nearby sandy channel can provide a rapid pathway for saline water. Tidal creeks, palaeochannels and fractures around poorly constructed wells can also connect shallow saline zones with deeper groundwater.

Salinity ingress is not always visible at first. Electrical conductivity and chloride may rise before water develops an obvious salty taste. Irrigated crops may show reduced yields, soil degradation or leaf damage, while household users may experience corrosion in pipes and appliances. A sound assessment therefore needs hydrogeological mapping, seasonal water-level records and laboratory testing rather than relying on taste or isolated well samples.

Odisha Case Studies Along The Coast

The districts of Kendrapara and Jagatsinghpur illustrate the complexity of managing groundwater in a deltaic setting. Villages near tidal rivers and coastal embankments can experience brackish groundwater in shallow wells, particularly during dry months. Domestic demand, irrigation and aquaculture can draw on the same groundwater system, while cyclones and storm surges may temporarily add salt to ponds, soils and shallow aquifers.

Puri provides a different combination of pressures. The district has a major pilgrimage and tourism economy, expanding urban demand and agricultural activity. Seasonal population increases place additional pressure on local water supplies, while coastal sands can allow rapid movement of both recharge and contaminants. Monitoring must distinguish between short-term salinity caused by storm-related flooding and longer-term changes linked to pumping and recharge.

Further south, coastal parts of Ganjam show how groundwater quality can vary between villages only a few kilometres apart. The influence of lagoons, river mouths, irrigation practices and local geology makes a single district-wide solution unsuitable. Comparable investigations in Balasore and Bhadrak underline the importance of mapping aquifer boundaries and identifying freshwater pockets before new production wells are approved.

These cases should not be interpreted as evidence that every coastal well is at immediate risk. They show that salinity is spatially uneven and that management has to operate at aquifer scale. A village may retain a reliable freshwater lens while an adjacent bore becomes saline because it is deeper, too close to a tidal channel or screened across the wrong geological layer.

Monitoring That Detects Change Early

A reliable monitoring network combines observation wells, automatic water-level recorders, rainfall data, pumping records and periodic testing for electrical conductivity, chloride, sodium and other indicators. Sampling should cover pre-monsoon and post-monsoon conditions, because recharge and seasonal pumping can change the position of the freshwater–saltwater interface.

Field teams need consistent procedures for well selection, sensor placement, calibration and data validation. Practical advice on digital recorder guidance can help improve the quality of continuous water-level observations. A sudden water-level decline combined with increasing conductivity is more informative than either measurement alone.

Remote sensing and geographic information systems can strengthen field observations. Satellite imagery can identify land-use change, expanding aquaculture ponds, new roads and urban surfaces that alter recharge. Electrical resistivity surveys and bore-log interpretation can help locate saline layers and freshwater zones, while isotope or tracer studies may clarify whether salinity comes from modern seawater, trapped formation water or evaporated surface water.

For Australian practitioners, this approach is relevant in Perth’s superficial and fractured-rock aquifers, where groundwater supports wetlands, gardens and urban development. Household bore use, reticulated irrigation and dry summers can produce localised drawdown even when a regional water balance appears stable. Continuous monitoring gives regulators and communities time to adjust extraction before irreversible quality deterioration occurs.

Management Options For Freshwater Security

The first management priority is to keep freshwater levels high enough to resist landward saltwater movement. This may involve licensing limits, seasonal pumping rules, wider spacing between production wells and restrictions on new bores in vulnerable zones. High-volume users should be required to report abstraction and maintain properly constructed wells with screened intervals matched to the target aquifer.

Artificial recharge can be considered where hydrogeology, water quality and governance arrangements make it safe. Stormwater, treated wastewater or captured monsoon runoff may be directed into recharge basins or injection systems, but only after risks from nutrients, pathogens, chemicals and clogging have been assessed. In Odisha, restoring ponds, wetlands and drainage channels may provide a lower-cost form of managed aquifer recharge while also reducing flood impacts.

Agriculture can reduce pressure through drip irrigation, crop selection, mulching and irrigation scheduling based on soil moisture. Where salinity is already affecting farmland, farmers may need salt-tolerant varieties, improved drainage or a shift away from water-intensive crops. Aquaculture development should include safeguards against seepage, pond leakage and the uncontrolled disposal of saline water.

Australia offers relevant policy comparisons. The Murray–Darling Basin shows how extraction limits, metering and water accounting can support shared groundwater management, although coastal aquifers require additional protection against seawater intrusion. In Western Australia, groundwater allocation planning recognises the need to protect wetlands and dependent ecosystems. In Queensland, the Water Act 2000 provides a statutory framework for allocating and managing water resources, while local planning controls influence bore construction and coastal development.

Governance, Communities And Adaptation

Technical data becomes useful only when it informs decisions that local users can understand and trust. Odisha’s coastal groundwater planning needs cooperation among state agencies, panchayats, farmers, fishery operators, industries and households. Village-level water committees can help identify changing well conditions, discourage unsafe deepening and support shared rules during dry periods.

Aquifer maps should be presented in accessible formats, with clear explanations of recharge areas, vulnerable zones, water-quality trends and recommended pumping practices. The NAQUIM platform’s state, district and block-level resources can support this process by bringing together exploration results, aquifer characteristics, hydrology, water quality and management studies. The wider groundwater information portal also helps users connect technical evidence with planning and policy work.

Community participation is particularly important after cyclones. A storm surge can contaminate shallow wells, and residents may resume using them once floodwater recedes even though salinity remains elevated. Rapid post-event testing, temporary drinking-water supplies, well disinfection and advice on flushing or abandoning damaged wells can reduce health risks. Longer-term recovery should include checks on embankments, ponds, recharge structures and sanitation systems.

Australian communities face related decisions in different institutional settings. Residents in coastal towns may use rainwater tanks for gardens, rely on desalinated or reticulated water for drinking, and maintain private bores for lawns or small holdings. Water restrictions, bore licensing, drought declarations and urban development approvals need to work together so that private convenience does not undermine wetlands, neighbouring users or future supply.

Building A Long-Term Coastal Water Strategy

A durable strategy begins with a conceptual model of each aquifer system. This model should describe recharge sources, groundwater flow directions, geological barriers, pumping centres, tidal influences and likely salinity pathways. It should then be tested against water-level and water-quality observations and updated as new bore logs, climate records and extraction data become available.

Risk zoning can guide practical decisions. Areas with stable freshwater levels may support carefully controlled use, while transition zones require closer monitoring and extraction limits. High-risk areas near tidal channels, estuaries or heavily pumped well fields may need alternative supplies, managed retreat from groundwater dependence or strict restrictions on new abstraction.

Climate change makes this work more urgent. Sea-level rise can increase the inland reach of saline water, while changing rainfall patterns may reduce recharge. More intense cyclones can cause sudden contamination, and hotter conditions can increase irrigation demand. Adaptation therefore needs both infrastructure and demand management: protected recharge areas, resilient water treatment, efficient irrigation, emergency supply plans and reliable monitoring.

Odisha’s experience demonstrates that salinity ingress is a management problem as much as a geological one. Mapping identifies where the aquifer is vulnerable; monitoring shows when conditions are changing; regulation controls pressure on the resource; and community action protects shared supplies. The same sequence can guide coastal groundwater planning in Australia, provided local geology, legislation and water-use patterns are incorporated.

Government departments, researchers, utilities, consultants and community organisations can use NAQUIM resources to examine aquifer conditions, compare management approaches and support evidence-based decisions. Explore the available district and block information, review coastal water-quality evidence and apply monitoring and demand-management measures before saline impacts become permanent. Protecting freshwater aquifers now is more effective and less costly than trying to restore them after widespread contamination.