Developing a Pilot Operational Oceanography System for an Enclosed Basin

Stamatios Petalas,Angeliki Sampatakaki,Agisilaos-Alexandros Dimitrakopoulos,Ioannis Mamoutos,Vassilis Zervakis

doi:10.3390/jmse8050336

Stamatios Petalas, Angeliki Sampatakaki + Show 3 more

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https://doi.org/10.3390/jmse8050336

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Abstract

The first stages of the development of a pilot oceanographic observatory for an enclosed basin (Kalloni Gulf, Lesvos, Greece) are described. The focus of the present work is related to the estimation of the water exchange with the open sea, using a numerical model of the region, volume flux measurements based on current velocity, and sea-level measurements. Three different methods of assessment of the exchange are described and evaluated, in order to select a reference method to calibrate submarine telephone cable measurements. The high-resolution coastal circulation model for the enclosed sea, nested in a larger-domain model, is developed and evaluated against in situ data, focusing on the adequate representation of the exchange and the hydrographic structure in the basin. Monitoring the water level is selected as the best-suited method for estimating the water exchange in hourly-to-weekly time scales. The model reproduces adequately the tidal exchange and sea-level response, as well as the hydrographic characteristics of the basin. The cable voltage measurements exhibit tidal signals overwhelmed by low-frequency noise, possibly attributable to circuitry and ground failures; however, the most suitable method for estimating exchanges of the basin with the open sea appears to be sea-level monitoring.

Highlights

Enclosed and semi-enclosed coastal marine basins constitute areas of specific oceanographic interest due to their role as sources of anomalous property waters for the open sea, as well as their socioeconomic significance [1]
Where V is the volume of the basin, Qnet the net water volume flux rate exchanged with the open sea through the strait, P the precipitation rate, R the land effluents’ rate and E the evaporation rate over the basin
The submarine telephone cable provides us with a means to measure the voltage between the two shores across the strait and convert that to Qnet measurements, assuming a net volume flux versus voltage curve is constructed to be used as the calibration curve

Summary

Introduction

Enclosed and semi-enclosed coastal marine basins constitute areas of specific oceanographic interest due to their role as sources of anomalous property waters for the open sea, as well as their socioeconomic significance [1]. In addition to the role that these basins play in the circulation and hydrography of the neighboring open sea, the specific hydrographic and biogeochemical characteristics of these basins greatly enhance their ecological and socioeconomic importance [5] Due to their limited geographical area and the concentration of human population and activities there, enclosed basins exhibit a much higher sensitivity to human impacts [6] and there is a pressing need for drafting comprehensive and effective management policies, especially due to the range of contrasting pressures and demands from the different coastal stakeholder groups. The aim of drafting management policies for a coastal region requires exceptionally good understanding of the natural and anthropogenic processes and their ecological and socioeconomic impacts, and the associated development of monitoring and forecasting tools e.g., [7]

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