Uncertainty in river discharge forcings and error range on nowcasting numerical simulation of salinity and seawater temperature in Ise Bay, Japan.

We estimated the error range of the simulated salinity and seawater temperature based on the uncertainty of the river discharge into Ise Bay in a nowcasting numerical simulation model. We used two methods for calculating the river discharge forcing. In the first method, precipitation was used as the input for the storage function method. In the second method, the Basin Rainfall Index was used, which is a nowcasting dataset of river discharge simulated by the Japan Meteorological Agency. The uncertainty in annual river discharge in both methods was estimated to be within ±30 %. Simulations were conducted using the hydrodynamic simulation model. Annual simulation error ranges associated with the uncertainty in river discharge for salinity and seawater temperature were estimated to be approximately ±1.2 and ±0.15 °C, respectively. We proposed a practical research procedure that can be applied to other models and the simulation of the water environment of coastal and estuary areas.