Prediction of Daily River Discharge to Estuaries Based on Meteorological Data

A methodology is proposed to predict the daily river discharge (RD) to estuaries from rivers draining in similar temperate zones. Multiple regression models are proposed to estimate RD using only available meteorological data. The models are based on monthly air temperature (T) and recent (PR) and non-recent (PNR) atmospheric precipitation (rainfall). They consist of the linear and nonlinear terms of T, PR, and PNR, without interaction terms between them. Four rivers located in the north and centre of Portugal (flowing to the Atlantic Ocean) are used in this study—Vouga, Antuã, Neiva, and Mondego. The optimal period used to compute the recent precipitation history is between 4 and 7 days for Vouga, Antuã, and Mondego and is 11 days for Neiva. The recommended lag to compute the non-recent precipitation history is between 50 and 90 days. The optimisation of the lengths of recent and non-recent periods improved the model performance, compared with previously proposed models with interaction terms between the meteorological variables. The obtained models provide a clear interpretation of the impact that meteorology has on RD. All rivers showed similar responses, but the flows of bigger rivers (Vouga, Mondego) were more significantly affected by precipitation and temperature. The proposed models are useful for analysing biogeochemical processes in rivers and estuaries, as well as for assessing flood and drought risks in sensitive areas.