Characterisation of the Water Renewal in a Macro-Tidal Marina Using Several Transport Timescales

Abstract

In this paper, we investigate the water renewal of a highly populated marina, located in the south-west of France, and subjected to a macro-tidal regime. With the use of a 3D-numerical model (TELEMAC-3D), three water transport timescales were studied and compared to provide a fully detailed description of the physical processes occurring in the marina. Integrated Flushing times (IFT) were computed through a Eulerian way while a Lagrangian method allowed to estimate Residence Times (RT) and Exposure Times (ET). From these timescales, the return-flow (the fraction of water that re-enters the marina at flood after leaving the domain at ebb) was quantified via the Return-flow Factor (RFF) and the Return Coefficient (RC) parameters. The intrinsic information contained in these parameters is thoroughly analysed, and their relevance is discussed. A wide range of weather-marine conditions was tested to provide the most exhaustive information about the processes occurring in the marina. The results highlight the significant influence of the tide and the wind as well as the smaller influence of the Floating Structures (FS) on the renewal. Besides, this study provides the first investigation of the water exchange processes of La Rochelle marina. It offers some content that interest researchers and environmental managers in the monitoring of pollutants as well as biological/ecological applications.

On characteristic hydraulic times through hydrodynamic modelling: discussion and application in Patos Lagoon (RS)

“…Água vol. 15 n. 2, e2456 -Taubaté 2020 methodologies (Deleersnijder et al, 2001;Li and Shen, 2015;Qi et al, 2016;Viero and Defina, 2016;Huguet et al, 2019). Here, the analysis of Water Age allows us to analyze the average time that the water remains in the predefined domain over time.…”

“…Despite the extensive use of CHT analysis, there is no consensus in definitions, concepts and methodologies. As a result, several definitions of characteristic hydraulic timescales have been published (Bolin and Rodhe, 1973;Zimmerman, 1976;Monsen et al, 2002;Delhez et al, 2014;Cucco and Umgiesser, 2015;Liu et al, 2017;Huguet et al, 2019). There are several concepts that are different from each other but are closely related between them, thus very precise definitions are necessary to obtain correct result interpretations.…”

Residence Time Analysis in the Albufera of Valencia, a Mediterranean Coastal Lagoon, Spain

“…However, in lentic ecosystems, with and without tidal influence, the importance of renewal is decisive in their hydrodynamics, influencing the physical, chemical and biological processes that take place in these water bodies [4]. On the one hand, the water masses subjected to the action of the tides suffer the flow produced by the daily rise and fall of the tide and with it the consequent renewal [5]. This is the case of the Venice Lagoon (Italy), where the cleaning capacity of the basin is influenced by the renewal mechanism produced by the tidal exchange [6].…”

Numerical Simulation of Water Renewal Timescales in the Mahakam Delta, Indonesia

“…The exposure time is the total time spent by a water parcel in the domain of interest [4], and this timescale, combined with the residence time, allows estimating the return coefficient [5,25,26], a measure of the propensity of water parcels to re-enter the domain of interest after leaving it for the first time. These considerations suggest that age, residence time, and exposure time can be used as indicators to assess the transport rates of substances in estuaries and coastal regions [5,12,[27][28][29] as well as (with suitable modifications) to assist in developing reliable predictive models for clustering floaters (i.e., particles of intermediate density staying close to the water-air interface because of their positive buoyancy) on the free surface of a turbulent flow and for quantifying floaters distribution dynamics [30,31].…”