Nutrient distribution mapping model of the Bera River basin in Saleh Bay, West Nusa Tenggara

Saleh Bay is a semi-enclosed marine ecosystem that is vulnerable to nutrient inputs from surrounding watersheds. This study aimed to map the spatial distribution of watershed-derived nutrients and assess their implications for coastal water quality using numerical modeling. Simulations incorporated wind, tides, bathymetry, river discharge, and in- situ concentrations of dissolved oxygen (DO), nitrate (NO₃), ammonia (NH₄), and phosphate (PO₄). Hydrodynamic model validation against the current Copernicus Marine Service data showed strong performance, with RMSE values of 0.0316–0.0340 and correlation coefficients exceeding 0.97. Nutrient simulations indicated generally low NH₄ (