Quantifying wind contribution to water exchange in marinas using an improved analytical formulation

Water exchange is a key factor affecting environmental conditions in marina basins,
particularly in microtidal environments where tidal forcing alone may not ensure
adequate seawater renewal. This paper presents an improved analytical formulation that
extends the classical tidal prism approach by incorporating the contribution of windinduced circulation to water exchange. The formulation was developed using threedimensional hydrodynamic simulations performed with MIKE 3 FM and tracer-based
analyses of e-folding time. The investigation was carried out on hypothetical marina
configurations with characteristic length-to-width ratios of L/B = 1 and L/B = 2, sidepositioned entrances, and flushing culverts embedded in the breakwater structure.
Numerical simulations showed that water exchange is significantly influenced by wind
velocity, wind direction, tidal forcing, and exchange area. The characteristic wind
directions E, SE, W, and NW produced the most efficient water exchange, while
increasing wind velocity and effective exchange area generally resulted in shorter efolding times. The proposed formulation was validated against numerical model results
and also applied to Marina Opatija as a real-case study. The results showed good
agreement between analytically calculated and numerically simulated e-folding times.
The developed formulation provides a practical engineering tool for rapid assessment
of short-term water exchange and comparison of marina design alternatives under
microtidal conditions