Introduction

Coastal aquifers are among the most vulnerable groundwater systems in the world. Increasing population pressure, urbanization, industrial growth, tourism, and intensive groundwater abstraction along coastlines have led to a growing threat of sea water intrusion into freshwater aquifers.

Sea water intrusion compromises groundwater quality, renders wells unusable, affects agriculture and drinking water supply, and poses long-term risks to coastal water security. Once salinization occurs, recovery of coastal aquifers is often slow, costly, and technically challenging.

Sea water intrusion assessment and coastal aquifer management therefore play a critical role in ensuring sustainable freshwater availability in coastal regions.

At Hydrodynamic Modeling Consultancy Pvt. Ltd., we deliver integrated coastal aquifer management solutions combining hydrogeological investigations, numerical modelling, monitoring, and policy-aligned management strategies.

What Is Sea Water Intrusion?

Sea water intrusion is the landward movement of saline seawater into freshwater aquifers due to an imbalance between freshwater hydraulic pressure and seawater pressure.

Primary Causes of Sea Water Intrusion

• Excessive groundwater abstraction in coastal zones

• Decline in freshwater recharge

• Lowering of groundwater table below sea level

• Reduction in river flows and natural barriers

• Climate change, sea level rise, and extreme events

In coastal aquifers, freshwater normally floats above seawater due to density differences. Disturbance of this balance allows saline water to migrate inland and upward into wells.

Impacts of Sea Water Intrusion

Sea water intrusion has wide-ranging environmental, economic, and social consequences:

• Salinization of drinking water sources

• Reduced agricultural productivity due to saline irrigation water

• Corrosion and damage to industrial infrastructure

• Increased treatment costs for water supply systems

• Long-term degradation of coastal aquifer systems

These impacts make early detection and proactive management essential.

Importance of Coastal Aquifer Management

Coastal aquifer management aims to control, prevent, and reverse saline intrusion while ensuring sustainable groundwater use.

Objectives of Coastal Aquifer Management

• Maintain freshwater–seawater equilibrium

• Regulate groundwater abstraction

• Enhance freshwater recharge

• Protect drinking water sources

• Build climate-resilient coastal water systems

Effective management requires science-based planning and continuous monitoring.

Key Components of Sea Water Intrusion Assessment

1. Hydrogeological and Aquifer Characterization

• Delineation of coastal aquifer geometry and boundaries

• Identification of confined, unconfined, and multi-layered aquifers

• Assessment of hydraulic properties and groundwater gradients

2. Groundwater Level and Salinity Monitoring

• Monitoring of groundwater levels relative to mean sea level

• Electrical conductivity (EC), TDS, and chloride profiling

• Identification of saline fronts and transition zones

3. Geochemical and Isotopic Analysis

• Differentiation between marine intrusion and other salinity sources

• Mixing analysis of freshwater and seawater

• Identification of upconing and lateral intrusion processes

4. Numerical Modelling of Sea Water Intrusion

Numerical models provide predictive understanding of intrusion dynamics.

Applications include:

• Simulation of freshwater–seawater interface movement

• Assessment of abstraction and recharge scenarios

• Evaluation of barrier and mitigation measures

Density-dependent models such as SEAWAT are widely used for coastal aquifer studies.

Coastal Aquifer Management and Mitigation Strategies

Demand-Side Management

• Regulation and reduction of groundwater abstraction

• Shifting pumping away from vulnerable coastal zones

• Conjunctive use of surface water and groundwater

Supply-Side and Structural Measures

• Artificial recharge and Managed Aquifer Recharge (MAR)

• Freshwater injection and hydraulic barriers

• Recharge through treated wastewater or stormwater

• Restoration of wetlands and recharge zones

Policy and Regulatory Measures

• Coastal groundwater zoning and abstraction controls

• Protection of drinking water well fields

• Integration with coastal zone management plans

• Long-term monitoring and compliance frameworks

Case Study: Sea Water Intrusion Assessment for a Coastal Industrial Cluster

Project Background

A coastal industrial and urban cluster experienced rising salinity in groundwater wells, threatening drinking water supply and industrial operations.

Key Challenges

• High groundwater abstraction close to the coastline

• Declining recharge due to urbanization

• Absence of systematic monitoring

Hydrodynamic Modeling Consultancy Pvt. Ltd. – Approach

• Hydrogeological and coastal aquifer characterization

• Groundwater level and salinity monitoring network design

• Density-dependent groundwater modelling to simulate intrusion

• Evaluation of abstraction control and recharge scenarios

• Development of a coastal aquifer management plan

Outcomes

• Identification of intrusion-prone zones

• Optimized abstraction and recharge strategy

• Stabilization of groundwater salinity trends

• Improved regulatory confidence and water security

How Hydrodynamic Modeling Consultancy Pvt. Ltd. Supports Coastal Aquifer Management

We provide end-to-end sea water intrusion and coastal aquifer management services, including:

• Coastal hydrogeological and aquifer investigations

• Groundwater level and salinity monitoring programs

• Sea water intrusion assessment and mapping

• Density-dependent groundwater modelling (SEAWAT)

• Managed Aquifer Recharge (MAR) and barrier design

• Policy-aligned coastal groundwater management plans

• Regulatory and compliance support

Our solutions are science-driven, climate-resilient, and regulator-ready.

Why Sea Water Intrusion Management Is Critical

• Protects drinking water sources in coastal regions

• Prevents irreversible aquifer salinization

• Supports sustainable urban and industrial growth

• Enhances climate resilience against sea level rise

• Reduces long-term water treatment and infrastructure costs

Sea water intrusion management is a strategic necessity for coastal sustainability.

Conclusion

Sea water intrusion represents one of the most serious threats to coastal groundwater resources. Without timely assessment and proactive management, coastal aquifers can suffer long-term and often irreversible damage.

Hydrodynamic Modeling Consultancy Pvt. Ltd. delivers integrated sea water intrusion and coastal aquifer management solutions that combine hydrogeology, advanced modelling, monitoring, and policy frameworks—ensuring sustainable freshwater security in coastal environments.