The impact of salinity intrusion on rice productivity

Abstract

More than half of Vietnam's national rice production is produced in the Mekong Delta. Many hectares of rice were damaged due to extensive salinity intrusion during the dry season of 2016. The impact of salinity intrusion on rice production is studied by (1) mapping the impact using remote sensing data (MODIS NDVI time-series) and (2) investigating how the impact affects farmers' lives. Ground data is collected in Soc Trang province through interviews with commune officials and farmers. Quantitative data includes damages to rice areas as aggregated by the local government and land use points for classification.

Rice areas are mapped through supervised classification, using extreme gradient boosting. Peak detection analysis is used to distinguish distinct rice cropping schedules within district boundaries. Compared against an evaluated climatology, hampered rice growth is mapped for two hot-spots (Long Phu and Nga Nam district). This can be attributed to salinity problems through interpretation of ground collected information and an understanding of the local salt-intrusion mechanisms. Reconciling affected rice grid cells mapped through satellite analysis with hectares of damaged rice recorded by the local government is difficult.

Analyzed perspectives of salinity affected farmers highlight the uncertain current conditions and future for rice production in the Mekong Delta. Local government officials and farmers feel the changing climate conditions and the urge to respond through preventive or adaptive measures to avoid similar impacts of salinity intrusion in the future. In this research, soft information gathered through interviews provided contextual learning opportunities to better direct, develop and interpret remote sensing analysis and results.