Tác động thủy văn - sinh thái của hệ thống thủy lợi Cái Lớn-Cái Bé đến sản xuất tôm-lúa và cây trồng nước ngọt: phân tích quan trắc trước- sau vận hành

Abstract

This study evaluates the relationship between hydro-ecological variations (salinity and water level) and agro-aquaculture productivity following the pilot operation of the Cai Lon - Cai Be irrigation system during 2021-2023. The dataset includes observations from 12 monitoring stations (2020-2023) and production data of shrimp and rice across the Winter-Spring, Summer-Autumn, and Main cropping seasons. Data were standardized by season, and two indicators were derived: the Salinity Exposure Index (SI) and the Coefficient of Variation (CV), reflecting salinity magnitude and stability. A multivariate linear regression model (OLS) was then applied to quantify the effects of SI, average water level, and timing of initial water intake on yield. Results show that after system operation, mean salinity decreased by 10-20%, daily salinity fluctuation declined by nearly 50%, and the stable salinity duration for shrimp culture increased by 10-15 days; meanwhile, water level variation within the canal network was maintained within ±0.15 m. Correspondingly, shrimp yield increased by 10-12% and rice yield by 6-8%, with the most notable improvement observed in the transitional zone of An Bien - Go Quao. The regression model achieved R² = 0.76; F, p < 0.001, indicating a statistically significant relationship, where SI negatively and Havg and Mintake positively affect yield. The findings suggest that operating the system under a tidal-window regime allowing early salinity intake and late freshwater flushing combined with automated monitoring and community-based regulation, can optimize hydro-ecological balance and enhance climate resilience for shrimp-rice and freshwater farming zones.