A process-driven biogeochemistry model, Wetland Carbon Assessment Tool - DeNitrification-DeComposition model (WCAT-DNDC) was validated and applied to examine the responses of daily net ecosystem exchange (NEE), net primary productivity (NPP), ecosystem respiration (ER), methane (CH4) and nitrous oxide (N2O) emissions in the Lake Maurepas swamp forests under dry (2011), normal (2019), and wet (2021) conditions, SLR (low 0.27 m and high 0.50 m over the next 50 years), and a Mississippi River (MR) diversion with various hydrologic and salinity regimes. Model simulations were conducted at twelve Coastwide Reference Monitoring System (CRMS) sites that were classified as three habitats (throughput, relict, and degraded) inside the Lake Maurepas swamp forests.