Developing Indicators for Adaptive Capacity in Rice Farming Under Saltwater Intrusion in the Philippines and Vietnam

Challenge

Saltwater intrusion threatens rice yields and livelihoods in coastal areas of the Philippines and Vietnam, intensified by climate change.

Solution

Researchers developed and tested multidimensional indicators to assess and strengthen farmers’ capacity to adapt to saltwater intrusion.

Overview

Rice is a staple food and a key source of livelihood in Southeast Asia. In coastal areas of the Philippines and Vietnam, however, saltwater intrusion – the movement of saline water into freshwater zones – is becoming a serious challenge. This process, often worsened by sea level rise, tidal surges, and changing rainfall patterns, reduces soil productivity and damages crops. As rice is sensitive to salinity, even small increases in salt levels can lead to substantial yield losses.

With support from the Asia-Pacific Network for Global Change Research (APN), a research team led by Catherine Roween C Almaden (Xavier University – Ateneo de Cagayan, Philippines) worked with partners in both countries to understand how farming households adapt to this problem. The project aimed to develop and apply a set of multidimensional indicators, consolidated into a Measure-based Adaptation Index (MAI), that could measure adaptive capacity – the ability of communities to adjust, cope, and recover in the face of environmental change.

Understanding saltwater intrusion impacts

Saltwater intrusion disrupts rice farming in multiple ways. It can cause soil degradation, force farmers to switch to less profitable crops, or require expensive mitigation measures such as building dikes and installing pumps. It also affects water availability for irrigation and domestic use. The team recognized that adaptation is not just a matter of technology or infrastructure – it involves social, economic, institutional, and environmental factors.

Developing multidimensional indicators

To capture this complexity, the researchers designed indicators across several dimensions: human, social, financial, physical, and natural capital. These dimensions reflect, for example, access to knowledge and training, community networks, availability of credit or savings, condition of farming equipment and infrastructure, and quality of natural resources. The results from these dimensions were combined into the MAI, a composite score that quantifies a household’s overall adaptive capacity.

Data were collected from 326 coastal rice farmers in Northern Mindanao in the Philippines and 258 rice farmers in in the Mekong Delta, Vietnam. The KoBoCollect app was used on Android devices to collect household survey data efficiently in the field, ensuring accuracy and speed. Additional insights came from interviews and focus group discussions with local government officials, agricultural extension workers, and community leaders.

Findings and results

The MAI and its component indicators helped identify strengths and gaps in adaptive capacity at the household and community level. In the Philippine study site of Plaridel, Misamis Occidental, strong social networks and active farmer organizations provided mutual support, boosting adaptive capacity. In contrast, in Vietnam’s Ben Tre and Tra Vinh provinces, limited financial resources were the main constraint on adaptation.

Results highlighted that:

• Income diversification: In both countries, households with diverse income sources, such as combining rice farming with aquaculture or small trade, were more resilient to crop losses.
• Access to knowledge: Training on saline-tolerant rice varieties improved farmers’ confidence in adaptation practices.
• Communal infrastructure: Investment in shared irrigation systems, especially those covering many hectares, reduced individual costs and risks.

Capacity building and policy relevance

Beyond the research, the project engaged stakeholders through discussions, interviews, and training in Plaridel, Misamis Occidental, and the Vietnam sites of Ben Tre and Tra Vinh, to validate the indicators and the MAI, and to discuss practical applications. These sessions included farmers, local government units, agricultural extension workers, and provincial policymakers. The project’s findings highlighted several region-specific challenges, including the seasonal peak in salinity levels in the Mekong Delta during the dry season (February–April).

Policymakers could use the MAI and its indicators to target support programs, such as subsidies for salt-tolerant seeds, credit schemes for households with limited financial capital, or technical assistance for upgrading communal irrigation systems covering many hectares. The framework also provides a basis for monitoring adaptation progress over time, enabling comparison between areas with strong social networks and those with weaker institutional support, and tracking improvements in household resilience metrics year by year.

Outlook

The project combined scientific assessment with local knowledge to create tools, including the MAI, that can guide immediate and long-term adaptation strategies. Scaling up the use of these indicators in other coastal rice-growing regions could help safeguard food security and livelihoods in the face of climate change.

Project details

Acknowledgements

This project was supported by the Asia-Pacific Network for Global Change Research (APN) under its Collaborative Research Programme for Young Researchers (CRYS). Acknowledgedment is also given to the participating farming communities, local government units, and partner institutions in the Philippines and Vietnam for their valuable contributions.

Related information

• Project Permalink
• Project Final Report
• Almaden, C. R. C., Rola, A. C., Baconguis, R. D., Pulhin, J. M., Camacho Jr, J. V., & Ancog, R. C. (2019). Determinants of Adaptation for Slow-Onset Hazards: The Case of Rice-Farming Households Affected by Seawater Intrusion in Northern Mindanao, Philippines. Asian Journal of Agriculture and Development, 16(1362-2019-2696), 117-132. Retrieved from https://ajad.searca.org/read-articles/13-view-article?aid=963
• Almaden, C. R. C., Diep, T. T., Rola, A. C., Baconguis, R. D. T., Pulhin, J. M., Camacho, J. V., & Ancog, R. C. (2020). Factors Influencing Measure-based Adaptation of Rice Farmers for Slow-Onset Hazard: the Case of Saltwater Inundation in the Philippines and Vietnam. Environmental Management. doi:10.1007/s00267-020-01332-2
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