Geological structure and seabed morphology of the Stoupa submarine groundwater discharge system,Messinia, Greece

Detailed marine geological–geophysical survey of the submarine groundwater discharge (SGD) system at Stoupa, Messinia (Greece) was conducted as part of an offshore study aiming at the evaluation of the discharge rate, the quality of the water and the investigation of potential ways for exploitation. Systematic mapping of the seafloor included swath bathymetry, seismic profiling and side-scan sonar imaging in order to reveal the precise morphology of the submarine discharge site, to better understand the structure of the SGD system and the nature and thickness of the sedimentary cover, and finally to provide the necessary data for a potential exploitation design. The SGD system is located in an E–W trending ellipsoidal depression characterized by two depth maxima at 27 and 29 m. This depression has been developed on the hanging wall of a N–S trending fault, whilst the groundwater discharges occur at the base of a 10-m-high steep and faulted rocky slope developed on conglomerates or limestone formations, also occurring in the coast. Recent sand deposits cover the seabed around the depression. The complex morphology of the discharge site, the steep slopes, and the rapid changes (due to erosion with subsequent slope collapse) during enhanced water flow periods, do not favor submarine constructions for the exploitation of the SGD system.     

An integrated GIS-based method for wind-power estimation: application to western Cyprus

This study presents an integrated method for the estimation and analysis of potential wind-energy resources in Cyprus, which is applied at selected sites on the western side of the island. Firstly, a statistical analysis of wind speed and direction data was conducted at six meteorological stations in western Cyprus, establishing daily, monthly and annual variations of wind speed. Also examined were the Weibull distributions of the wind at each site. These wind statistics serve as the basis for estimating corrected statistical distributions over the extended study areas, which were calculated using the Wind Atlas Analysis and Application Program (WAsP) that modifies wind flow estimates based on local topographic effects. As a result, a geographic and wind-resource database was formulated around each station. Aggregation of this data using statistical weighting methods allows the extrapolation of observed results and the visualization for selected hours of the day over the western part of Cyprus. The results indicate the strong influence of the sea-breeze on the island’s wind potential, and identify a number of areas of higher wind-energy potential suitable for wind-resource exploitation. It is hoped that both the methodology applied and results obtained can be further used by potential investors and wind-energy developers.     

Filling in missing sea-surface temperature satellite data over the Eastern Mediterranean Sea using the DINEOF algorithm

The Data Interpolating Empirical Orthogonal Functions method is a special technique based on Empirical Orthogonal Functions and developed to reconstruct missing data from satellite images, which is especially useful for filling in missing data from geophysical fields. Successful experiments in the Western Mediterranean encouraged extension of the application eastwards using a similar experimental implementation. The present study summarizes the experimental work done, the implementation of the method and its ability to reconstruct the sea-surface temperature fields over the Eastern Mediterranean basin, and specifically in the Levantine Sea. L3 type Satellite Sea-surface Temperature data has been used and reprocessed in order to recover missing information from cloudy images. Data reconstruction with this method proved to be extremely effective, even when using a relatively small number of time steps, and markedly accelerated the procedure. A detailed comparison with the two oceanographic models proves the accuracy of the method and the validity of the reconstructed fields.     

Circular plumes in Lake Pontchartrain estuary under wind straining

Circular shaped density plumes of low turbidity, low fecal indicator (Escherichia coli and enterococci) concentrations, and high salinity have been observed near the Industrial Canal in Lake Pontchartrain, north of the City of New Orleans. A conceptual model in polar coordinates and a numerical model are developed, together with data analysis, to illustrate the dense plume. It is demonstrated that the northward expansion of the plume occurs under northerly winds. The northward expansion of the plume occurs under northerly winds that drive downwind flow at the surface and upwind radial flow at the bottom. Northerly wind-induced straining, similar to tidal straining, promotes vertical stratification. As a result, the water becomes stratified near a thin bottom layer (<1 m), within which density currents are facilitated. The stability of the stratified plume suppresses wind-induced turbulent mixing inside the plume. The bottom water outside of the plume is more effectively stirred by the wind, the result being that the suspended sediment concentration outside of the plume area is much higher than inside. This contrast in mixing makes the plume visible from the surface by satellites even though the stratification is at the bottom. Laterally, wind stress produces a torque (vorticity) in areas of non-uniform depth such that upwind flow is developed in deep water and downwind flow in shallow water. The continuity requirement produces an upwind flow along the axis of the Industrial Canal (IC). The upwind flow is balanced by the downwind flow over the shallower peripheral areas along the coast.