Determination of nautical depth by density measurement and by acoustic sounding

Pilot investigations were carried out with the objective of testing the usefulness of measuring the density of the mud/water medium to determine nautical depths in the Port of Gdansk. Results show significallt differences between the nautical depth and the depth detennined by acoustic methods at loose bulk cargo terminals. It was also found that too large depth values were obtained when 33 kHz transducers were used. Applicability of acoustic profiling for distinguishing structure of deposits which must be dredged was tested

Morfologia dna Przekopu Wisły

Opened in 1895, the Przekop Wisły canal is a straight channel in the mouth of the Vistula River, which has been dug to adjust the hydrological situation in the Żuławy region. Recently, applying a multibeam echosounder has enabled the first comprehensive morphological registration and analysis of the bottom of the Przekop Wisły canal. The channel contains rapid, a side bar, a pool, and a front bar alongside sand dunes that have developed on the surface of these morphological units. The Przekop Wisły canal, in its current bathymetric situation, has been shown not to meet the conditions required for a free flow of water in case of considerable swelling, especially in case of an intense flow of drifting ice. No marine factors (naturally, apart from changes in sea level) were found to have a significant or direct effect on the morphology and sediments of the bottom of the Przekop Wisły canal.Uruchomiony w 1895 roku Przekop Wisły jest prostolinijnym fragmentem ujściowego odcinka Wisły wykonanym w celu uregulowania sytuacji hydrologicznej w rejonie Żuław. Zastosowanie echosondy wielowiązkowej umożliwiło przeprowadzenie pierwszej, dokładnej rejestracji rzeźby i analizy morfologicznej dna Przekopu Wisły. W obrębie koryta wyróżniono bystrze, odsyp boczny, ploso i odsyp środkowy wraz z rozwijającymi się na ich powierzchni falami piaszczystymi. Wykazano, że Przekop Wisły, w obecnej sytuacji batymetrycznej, nie spełnia w wystarczającym stopniu warunków do swobodnego spływu wód w przypadku dużych spiętrzeń, a szczególnie w sytuacji intensywnego spływu lodów dryfowych. Nie stwierdzono istotnych, bezpośrednich skutków wpływu czynników morskich (naturalnie oprócz zmian poziomu morza) na budowę dna przekopu i jego osadów

Nonlinear acoustical methods in the detection of gassy sediments in the gulf of Gdańsk

The application of nonlinear backscattering of acoustical signals in detection of gas bubbles in subsurface layer of sediment of the Gulf of Gdansk is presented. Gas bubbles concentration was estimated assuming that nonlinear scattering in soft sediments is similar as in water. Summary, difference and double harmonics generated only by gas bubbles were recorded and used for bubble density estimation. Comparisons of the concentrations received from different nonlinear components show generally agreement in calculated bubble density distributions, although values of densities acquired from almost identical volumes in a single transmission differ

The relief of the offshore sea bottom at Karwia-Chałupy, Polish Baltic coast

Morphology of sea bottom of the Władysławowo area, from Karwia to Chałupy, has been studied based on the detailed digital bathymetric map prepared in a scale of 1:25 000 with isobaths every 0.25 m. A significant differentiation of the bottom relief has been observed, with the level changes up to 1-3 metres, mostly connected with the occurrence of specific systems of ridges and runnels. They are probably partly relict forms (fluvial and/or coastal?), changed to certain degree during the rapid stage of the Litorina transgression, and in partly forms created by the recent waves. Several types of the sea bottom surface, differing in pattern of morphological forms, have been recognised within inshore, near shore, and open sea (above 16 m depths) areas. The full knowledge of the origin and development of these relief forms requires further specialised research, currently carried out. Nonetheless, the already obtained picture of the sea bottom relief indicates an intensified abrasion of the offshore sea bottom, and an intensive, irreversible sweeping out of the sediments from the shore to the open sea, most probably by rip currents, at a distance up to several kilometres from the shore. It is in accordance with the results of a former large-scale (1:500) study of the sea bottom at the test field at Chłapowo, performed with the use of an integrated system of non-invasive and direct methods