Comparative analysis of evapotranspiration and water yield in basins of the Northern Gulf of America between the past and next 40 years

Abstract

The Northern Gulf of America (NGOA, formerly known as Northern Gulf of Mexico) is a key economic region for seafood production, recreation, and marine transportation. This study compared evapotranspiration (ET) and water yield in the Sabine River Basin (SRB) and Pearl River Basin (PRB) along the NGOA, focusing on coastal watersheds between two 40-year weather scenarios: past (1985–2024) and future (2025–2064). The analysis was conducted using the HAWQS (Hydrologic and Water Quality System) model, along with Mann-Kendall (M-K) and Kolmogorov-Smirnov (K-S) tests. Simulations showed a two-month shift in the timing of maximum monthly water yield, moving from January in the past scenario to March in the future scenario at the coastal watersheds. Monthly water yield was closely correlated to monthly precipitation, indicating that precipitation played a crucial role in producing water yield. Seasonal ET was roughly twice as high in spring and summer compared to fall and winter, while seasonal water yield was about twice as large in spring and winter compared to fall and summer. Future annual ET at the coastal watersheds were moderately or slightly higher than that of the past, while both the past and future annual ETs were lower in the northernmost (inland) watersheds than in the southernmost (coastal) watersheds. Overall, impacts of weather variation on ET and water yield varied among basins in the NGOA. These findings offer valuable insights to water resource managers, helping them make more informed decisions to mitigate water evaporative losses and increase water yield in coastal watersheds of the NGOA and the similar conditions around the world.