Salinity’s Growing Impact on Agriculture in the Bengal and Mekong Deltas

Coastal regions and deltas are critical hubs of global and regional food security, supporting dense populations and diverse economic activities. However, these areas are increasingly vulnerable to salinization, driven by rising sea levels and upstream seawater intrusion. This problem is compounded during dry seasons by groundwater extraction, reduced freshwater inflows, and unsustainable agricultural practices. Despite its significance, the mechanisms and future dynamics of salinization in coastal and deltaic regions remain poorly understood.

A study conducted by CGIAR and Wageningen University focuses on the Ganges-Brahmaputra-Meghna (Bengal) Delta in southwest Bangladesh and the Mekong Delta in Vietnam, two of the world’s most climate-vulnerable regions and significant rice-producing areas. It aims to:

  1. Identify Current Salinity Hotspots (2010): Using combined water and soil salinity data to map areas with high salinity in both deltas.
  2. Project Future Salinity Hotspots (2050): Employing scenario SSP1/RCP 4.5 to model water and soil salinity changes, integrating machine learning for soil salinity projections.
  3. Assess Agricultural Vulnerability: Evaluating the impact of salinity on rice cultivation by identifying cropping areas affected by varying salinity levels.

Key Findings

1. Salinity Hotspot Mapping:

  • In the Bengal Delta, hotspots are concentrated upstream of the Sundarbans, where reduced freshwater flow exacerbates salinization.
  • In the Mekong Delta, the most affected regions are the low-lying southwest and southern coastal areas.

2. Future Projections:

  • Soil salinity is expected to increase in both deltas, with inland areas of the Bengal Delta and the eastern Mekong Delta becoming more affected.
  • High to medium salinity zones are projected to expand and move further inland, indicating a worsening scenario compared to current conditions.

3. Agricultural Impacts:

  • The areas of rice cultivation exposed to medium to high salinity are predicted to grow significantly, threatening future productivity.
  • While the exact yield reduction could not be determined due to the complex interactions between salinity levels and crop stages, the findings underscore the need for adaptation strategies.

Recommendations

To sustain current productivity levels, a shift toward adaptive saline agriculture is imperative. This involves coordinated efforts from farmers, government bodies, research organizations, civil society, private enterprises, and development partners. Enhanced field-level data collection and further studies are crucial to refine understanding and inform actionable strategies.

Food security

This research highlights the urgent need for proactive measures to address salinization in the Bengal and Mekong Deltas. By identifying current and future hotspots and assessing agricultural vulnerability, it provides a foundation for developing resilient agricultural practices and policies to safeguard food security in these critical regions.

Download the full report: Impact of Salinity on Agriculture of Ganges-Brahmaputra-Meghna Delta and Mekong delta.pdf
Islam, F., de Miguel Garcia, A., van Scheltinga, C.T., Gülpen, M., Biemans, H., Mondal, M., Urfels, A., Nelson, K. 2024. Impact of Salinity on Agriculture of Ganges-Brahmaputra-Meghna Delta and Mekong Delta. Technical report. Los Banos, Laguna: International Rice Research Institute.

Featured image: Rohan Reddy/Unsplash

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