Agricultural Sciences: Techniques and Innovations Vol. 4

The Plain of Reeds, a critical agricultural heartland within Vietnam's Mekong Delta, faces profound challenges from anthropogenic climate change. This chapter provides a comprehensive analysis of the impacts of climate change on the water resources essential for its intensive rice cultivation system. By integrating historical hydro-meteorological data (1984–2022) with future projections from an ensemble of Global Circulation Models (GCMs) under RCP4.5 and RCP8.5 scenarios, this study utilises the FAO-AquaCrop model to quantify shifts in irrigation water dynamics. Historical analysis reveals a discernible warming trend of approximately 0.2°C per decade and complex alterations in rainfall patterns, including an increase in dry-season precipitation and a strengthening of the El Niño-Southern Oscillation (ENSO) signal. Crucially, future projections indicate that despite a potential increase in total precipitation, the concurrent and more pronounced rise in air temperature will significantly elevate crop evapotranspiration rates. This leads to a projected increase in net Irrigation Water Demand (IWD) across all rice-growing seasons and emission scenarios. The Winter-Spring crop, cultivated during the driest period, is identified as the most vulnerable, with a substantial projected increase in water requirements. In response, this chapter evaluates adaptation strategies, demonstrating through model simulations that adjusting sowing calendars is a highly effective, low-cost measure. Advancing the sowing date of the Winter-Spring crop, for instance, can reduce IWD by up to 15.6% by better aligning crop growth with cooler temperatures and residual late-season rainfall. These findings provide a critical scientific basis for developing climate-resilient agricultural policies and water management strategies to safeguard the productivity and sustainability of the Plain of Reeds.