Linking freshwater hydrology to global food security in the Mekong Basin

Abstract Tropical flood pulse rivers are crucial for global food security, especially in developing nations. The Mekong River basin is one of the world’s most significant agricultural regions, sustaining millions through rice production and export. However, rapid hydrological changes from hydropower development, altered flow regimes, and climate variability threaten the flood pulses essential for rice cultivation. Using a multivariate autoregressive state space analysis, we examined how hydrological variability influences rice production across four lower Mekong basin countries: Cambodia, Laos, Thailand, and Viet Nam. Our study integrated high-resolution hydrologic and agricultural data spanning decades to assess the effects of flood magnitude, duration, and saline intrusion on rice yields. We found significant spatial tradeoffs, particularly in areas affected by flooding and salinity. In Viet Nam, large flood pulses mitigate saline intrusion and expand arable land but reduce cultivation efficiency likely due to fertilizer runoff. In Cambodia, where saline intrusion is minimal, excessive flooding lead to field inundation and reduced arable land, decreasing yields. Our findings reveal the complex interactions between hydrology, land use, and agricultural productivity, emphasizing the need for coordinated transboundary water management. By identifying key tradeoffs, this research informs decision-makers on optimizing agricultural strategies to ensure food system resilience amid changing hydrological and climatic conditions.