Eulerian and lagrangian transport time scales of a tidal active coastal basin

Abstract In this work the flushing features of a tidal active coastal basin, the Venice lagoon, have been investigated. The water transport time scale (TTS) has been computed by means of both an eulerian and a lagrangian approach. The obtained results have been compared in order to identify the main differences between the two methods. The eulerian water transport time (WRT) scale has been computed through the definition of the remnant function of a passive tracer released inside the lagoon whereas the lagrangian water transport time (WTT) scale has been computed tracking the trajectories of simulated particles released inside the basin. Both the methodologies rely on computer modeling. A 2D hydrodynamic model based on the finite element method has been used. The model solves the shallow water equations on a spatial domain that represents the whole Adriatic Sea and the Venice lagoon. Numerical computations show that the two techniques, when applied to a tidal active coastal basin, characterized by a complex morphology and dynamic, are differently influenced by the tidal variability. In particular, the type and the phase of the tidal forcing at the beginning of the computation strongly influence the WTTs distribution within the basin. On the other hand, the WRTs computation is not affected by the tidal forcing variability.

[1]  J. Kalff,et al.  Organic matter mineralization rates in sediments: A within‐ and among‐lake study , 1998 .

[2]  E. Moreno-Ostos,et al.  The residence time of river water in reservoirs , 2006 .

[3]  Georg Umgiesser,et al.  A finite element model for the Venice Lagoon. Development, set up, calibration and validation , 2004 .

[4]  D. Prandle,et al.  A modelling study of the mixing of 137Cs in the seas of the European Continental Shelf , 1984, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[5]  S. Carpenter,et al.  Pelagic responses to changes in dissolved organic carbon following division of a seepage lake , 1996 .

[6]  J. C. Andrews,et al.  Space‐time variability of nutrients in a lagoonal patch reef , 1983 .

[7]  A. Cucco,et al.  Modeling the water exchanges between the Venice Lagoon and the Adriatic Sea , 2008 .

[8]  J. Zimmerman,et al.  The tidal whirlpool: a review of horizontal dispersion by tidal and residual currents , 1986 .

[9]  H. Takeoka.  Fundamental concepts of exchange and transport time scales in a coastal sea , 1984 .

[10]  Nancy E. Monsen,et al.  A comment on the use of flushing time, residence time, and age as transport time scales , 2002 .

[11]  Deterministic Diffusion, Effective Shear and Patchiness in Shallow Tidal Flows , 1988 .

[12]  P Humeau,et al.  Numerical and experimental hydrodynamic studies of a lagoon pilot. , 2001, Water research.

[13]  G. Bendoricchio,et al.  A water-quality model for the Lagoon of Venice, Italy , 2005 .

[14]  A. Cucco,et al.  Development and validation of a finite element morphological model for shallow water basins , 2008 .

[15]  A. Cucco,et al.  Modeling the Venice Lagoon residence time , 2006 .

[16]  W. Boicourt,et al.  Model for Estimating Tidal Flushing of Small Embayments , 1992 .

[17]  D. Luketina.  Simple Tidal Prism Models Revisited , 1998 .

[18]  Thomas M. Powell,et al.  Interannual fluctuations in primary production: Direct physical effects and the trohic cascade at Castle Lake, California , 1990 .

[19]  H. Takeoka.  Exchange and transport time scales in the Seto Inland Sea , 1984 .

[20]  J. V. D. Kreeke,et al.  Residence Time: Application to Small Boat Basins , 1983 .

[21]  J. Zimmerman,et al.  Chaotic Stirring in a Tidal System , 1992, Science.

[22]  J. Zimmerman,et al.  Mixing and flushing of tidal embayments in the western Dutch Wadden Sea part I: Distribution of salinity and calculation of mixing time scales , 1976 .

[23]  柳 哲雄,et al.  Interactions between estuaries, coastal seas and shelf seas , 2000 .

[24]  Wim van Leussen,et al.  Physical Processes in Estuaries , 1988 .

[25]  H. Rodhe.  4 Modeling Biogeochemical Cycles , 1992 .

[26]  M. Darwish,et al.  TVD schemes for unstructured grids , 2003 .

[27]  J. Zimmerman,et al.  Some principles of mixing in tidal lagoons , 1982 .

[28]  Alain Norro,et al.  Application of COHERENS Model for Hydrodynamic Investigation of Sacca di Goro Coastal Lagoon (Italian Adriatic Sea Shore). , 2006 .

[29]  M. T. Babu,et al.  Modelling tide-driven currents and residual eddies in the Gulf of Kachchh and their seasonal variability: A marine environmental planning perspective , 2005 .

[30]  Ming-Hsi Hsu,et al.  Residence time of the Danshuei River estuary, Taiwan , 2004 .