Abstract
Numerical models are essential tools for the study and analysis of the hydrodynamics of estuarine systems. However, the model results contain uncertainties, which need to be minimized to increase the accuracy of predictions. In this work, the ensemble technique is proposed as a solution to improve hydrodynamic forecasts for estuarine regions. Two numerical models, openTELEMAC-MASCARET and Delft3D, were considered for the application of this technique to two Portuguese estuaries. Superensembles for three scenarios (summer, winter, and extreme event) were built to assess the effectiveness of the technique in improving water level prediction. Various weighing techniques were tested in the construction of the ensembles. Weighing techniques that consider the previous performance of each model alone outperformed other techniques. This was observed for all scenarios considered, at all sampling points and in both studied estuaries. The effect of the ensemble size was also analyzed. It was found that the size of the set is directly related to the prediction accuracy, with the best results provided by the superensembles with the highest number of elements. It is concluded that the combined use of several hydrodynamic models reduces the uncertainty of the results and increases the reliability and consistency of predictions for estuarine regions.
Highlights
Coastal regions, the estuarine areas, are of strategic importance from an environmental, economic, and social point of view
40% of the world population lives at a distance less than 100 km from the coast, and that percentage is increasing
Estuaries are dynamic coastal systems, with strong variations in salinity, currents, stratification, and water quality. They are subject to the influence of meteo-oceanographic and geomorphological phenomena such as wind, tides, waves, currents, river flows, transport of sediments, erosion, and Hydrodynamic Models Ensemble for Estuaries accretion
Summary
The estuarine areas, are of strategic importance from an environmental, economic, and social point of view They provide multiple ecosystem services, such as fishery and other food resources, leisure and tourism, energy, water, and raw materials. 40% of the world population lives at a distance less than 100 km from the coast, and that percentage is increasing This implies an increase in economic activities, coastal infrastructures, and urban intensification (Dangendorf et al, 2012; IPCC, 2012; Hallegatte et al, 2013; Moser et al, 2014; Bell et al, 2018). The massive occupation entails the artificialization of the banks, which leads to a loss of biodiversity, affecting both the physical and environmental properties of the water/land interface This increases the vulnerability of the system and, the risk to populations and their assets, with adverse effects on the economy (Peixoto, 2016). Considering the current context of climate change, an increase in the frequency and intensity of extreme events is expected (IPCC, 2012), with serious consequences for society and the environment, and with impacts on populations, infrastructures, habitats, and ecosystem services (Vose et al, 2014; Bell et al, 2018)
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