Rising Tides, Falling Harvests: Examining the Effects of Salinity Intrusion on Paddy Production in Lower Mekong Delta, Vietnam
Salinity intrusion, caused by global sea-level rise, is a major threat to paddy cultivation in the Mekong Delta of Vietnam (MKD). Salinity exposure reduces crop yields, increases soil salinity, and exacerbates fresh water scarcity, resulting in altered land use decisions and decreased paddy farming profitability. This study evaluates the effects of salinity intrusion on paddy yields and planted acreage, using a 21-year district-level panel dataset from the 13 provinces in the MKD. Specifically, we analyze the relationship between current salinity levels and paddy yield, as well as the relationship between lagged salinity levels and the paddy planted area. We examine these relationships across all districts, as well as for salinity-prone and non-salinity-prone districts and by proximity to the coast (20 km, 20-60 km, and 60+ km). The results indicate that salinity intrusion poses a significant challenge to paddy production in salinity-prone and coastal regions. Salinity level significantly and adversely affects paddy yields in salinity-prone and coastal districts. Similarly, high salinity levels in the past five years significantly reduce planted paddy acreage in these same regions. We also find that paddy yields in the MKD peaked in 2015 and have been declining since. The study highlights the regional differences in challenges associated with salinity intrusion in paddy production. Policymakers and agricultural managers need to take a region-specific approach to ensure that interventions are tailored to the specific needs and challenges faced by farmers. This entails supporting intensified paddy production in less salinity-prone areas and facilitating transitions to economically profitable alternatives to paddy in more salinity-prone areas.