1:21:00
Navigating the Salinity Crisis: Challenges of Saline Water and Soil in Coastal Bangladesh
EPICentre UCL
Overview
This webinar addresses the critical issue of water and soil salinity in coastal Bangladesh, framing it as a natural hazard with significant impacts on livelihoods, health, and food security. Dr. Shams highlights the unique geographical context of Bangladesh as a low-lying delta, making its densely populated coastal regions particularly vulnerable. The presentation delves into the scientific understanding of salinity, its seasonal variations, and long-term trends, supported by research from UCL and Dhaka University. It also explores various adaptation strategies, ranging from agricultural diversification to engineering solutions like managed aquifer recharge, while acknowledging the challenges of scalability and sustainability.
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Chapters
- Water and soil salinity is presented not just as an environmental issue but as a natural hazard with diverse impacts.
- High salinity negatively affects freshwater resources, human health (e.g., pre-eclampsia, high blood pressure), and food security by reducing crop yields and impacting livestock and fisheries.
- It also leads to land degradation, economic losses, infrastructure damage, ecosystem disruption, and can ultimately cause human displacement and migration.
- Drivers of salinity include natural factors like water-rock interactions, sea-level rise, and storm surges, as well as anthropogenic influences.
Recognizing salinity as a hazard helps prioritize interventions and understand its multifaceted threat to human well-being and development.
Pre-eclampsia is highlighted as a significant cause of maternal death in coastal Bangladesh, directly linked to high salinity exposure through drinking water.
- Bangladesh, situated on a low-lying mega-delta, has a large coastal population (around 35 million) directly exposed to salinity issues.
- The region experiences strong seasonal variations in rainfall, leading to water scarcity during the dry season when salinity levels rise.
- Surface water salinity is highly seasonal, peaking in the dry months, and long-term data shows a substantial increase in salinity in the southwest and southeast coastal areas.
- Shallow groundwater in coastal aquifers is often highly saline, exceeding recommended drinking water standards, and even deep groundwater can show elevated chloride levels in some areas.
Understanding the specific geographical and hydrological context of Bangladesh is crucial for developing targeted and effective solutions to the salinity crisis.
A map showing surface water salinity in Bangladesh clearly indicates high concentrations in the southwest coastal region, with seasonal variations reaching over 12,000 micromhos per centimeter.
- Long-term data reveals strong seasonal dynamics where soil and water salinity increase during the dry season and sharply decline with the onset of monsoon rains.
- Temperature peaks often correlate with salinity peaks, suggesting a link between higher temperatures and increased salt concentration, likely due to evaporation.
- While cyclones can impact salinity, their effect is more pronounced during the pre-monsoon season compared to the post-monsoon season.
- Rising sea levels and changes in sea surface salinity are identified as key factors influencing coastal salinity, with a generally rising sea level trend and a slight decrease in sea surface salinity observed over time.
Detailed scientific analysis of salinity trends and influencing factors provides the evidence base needed for accurate hazard assessment and predictive modeling.
Graphs show an inverse relationship between rainfall and salinity, with salinity levels peaking in March-April-May and dropping significantly with monsoon rains starting in June.
- Farmers are adapting by shifting from rice cultivation to more salt-tolerant and profitable crops like watermelons, maize, sunflowers, and beans.
- Innovative agricultural practices include creating floating beds for vegetable production in waterlogged areas and using mulching to reduce evaporation.
- Engineering solutions are being implemented, such as desalination through reverse osmosis, rainwater harvesting, and freshwater storage.
- Managed Aquifer Recharge (MAR) is a promising technique where freshwater is injected underground during the monsoon to create a freshwater lens for use in the dry season.
Exploring diverse adaptation strategies, from traditional farming adjustments to advanced engineering, is essential for building resilience against the pervasive salinity crisis.
Farmers are increasingly growing watermelons instead of rice in the dry season due to better profitability and lower water requirements in saline conditions.
- Despite technological feasibility, the sustainability of adaptation measures like MAR faces significant challenges, primarily due to socioeconomic factors and community engagement.
- Lack of willingness to pay for maintenance and a cultural perception of water as a free resource hinder the long-term operational success of community-managed systems.
- Institutional support from government agencies or NGOs is crucial for sustaining these interventions, as purely community-led models often struggle.
- Addressing salinity requires continuous technical and financial support from global communities and a focus on scalable, sustainable solutions that consider local socio-cultural contexts.
Understanding the barriers to sustainability is critical for refining future interventions and ensuring that adaptation efforts effectively address the long-term salinity threat.
Approximately 50% of the 100 Managed Aquifer Recharge schemes installed in coastal Bangladesh are currently not operating due to maintenance costs and community engagement issues.
Key takeaways
- Water and soil salinity is a significant natural hazard in coastal Bangladesh, impacting health, food security, and livelihoods.
- The low-lying deltaic geography of Bangladesh makes its coastal populations highly vulnerable to salinity intrusion.
- Salinity exhibits strong seasonal patterns, increasing in dry periods and decreasing with monsoon rains, influenced by temperature and rainfall.
- Long-term trends indicate a worrying increase in both surface and groundwater salinity in vulnerable coastal areas.
- Farmers are adapting through crop diversification and innovative agricultural techniques, while engineering solutions like MAR offer potential but face sustainability challenges.
- Socioeconomic factors, including community willingness to pay for maintenance, are critical determinants of the success of salinity adaptation measures.
- Addressing the salinity crisis requires a combination of technological innovation, robust institutional support, and international collaboration for scalability and long-term sustainability.
Key terms
Salinity CrisisNatural HazardCoastal BangladeshMega DeltaFood SecurityWater ScarcityGroundwater SalinitySurface Water SalinityManaged Aquifer Recharge (MAR)Adaptation StrategiesSea Level RisePre-eclampsia
Test your understanding
- How does water and soil salinity act as a natural hazard, and what are its primary impacts on human populations?
- What specific geographical and climatic factors make coastal Bangladesh particularly susceptible to salinity issues?
- Describe the seasonal dynamics of soil and water salinity in coastal Bangladesh and explain the role of temperature and rainfall.
- What are the main challenges associated with the sustainability of adaptation measures like Managed Aquifer Recharge in coastal Bangladesh?
- How are farmers in coastal Bangladesh adapting their agricultural practices in response to increasing soil and water salinity?