Towards a complete study of water renewal timescales of the Scheldt Estuary

de Brye, Benjamin [UCL] Debrauwere, Anouk [UCL] Deleersnijder, Eric [UCL]

Making sense of such a huge amount of information contained in present-day model outputs requires specific post-processing approaches presenting the model results in a format that is amenable to analysis. One of the strategies is to compute the timescales associated with the main processes occuring. These timescales synthesize the information hidden in the produced model results, and at the same time they give a quantitative insight into the dynamics and rate of functioning of the system. In this study we choose to follow this strategy to perform an in-depth analysis of the water renewal processes in the Scheldt Estuary. Applying the Constituent-oriented Age and Residence time Theory (CART, www.climate.be/CART) we compute the following timescales: (i) the age of the different renewing water types, (ii) the residence time, (iii) the exposure time, and (iv) the transit time. The numerical simulations are performed by the finite element model SLIM (www.climate.be/SLIM), which allows the use of a multiscale mesh going from the river scale (10 m) to the continental shelf break (100 km). We investigate the timescales interrelations and investigate how they vary in time and space. In order to further understand this spatio-temporal variability, we try to identify the major drivers of this variability.