Water renewal in the basins along the eastern Adriatic coast

Abstract

       Renewal time was calculated for a number of eastern Adriatic coastal basins. Three simple methods were used. Two of them used current meter data and the third one, salinity time series data.

       In introduction of the first two methods, the problem arises of how to define characteristic water renewal transport because of the eddies occurring at the en­trance; because of the small period oscillations, and because of the differences between the flow at different locations in the basin. Out of all the previously mentioned causes a part of water that enters the semiclosed basin spreads in the basin to a certain extent, and going off the entrance smaller and smaller volume of water takes part in the circulation. This difficulty was overcome either by a convenient averaging or by introduction of a special correction for the transport at the entrance.

       Third method uses salinity time series and is based upon the assumptions that increase or decrease of salinity is always due to the water of extreme salinity and that salinity fluctuations are in one sense either increasing during the entire time period of the calculation or decreasing during the entire period.

        The renewal time was calculated by all three methods for a number of basins along the eastern Adriatic coast. Though the currents in this area are not fast, renewal velocity is favourable from the pollution aspect. Ventilation of the basin in rather good and as marine biological production here is not too high, the area has good natural conditions for reasonable urbanization.