St. Ante Channel Project

St. Ante channel: The University of Zadar and the Ruđer Bošković Institute with the Šibenik, have decided to monitor hydrological features with Geolux as a partner in the St.Ante channel.

Krka National Park is located at the river Krka in southern Croatia. In the south, next to the waterfall, is Skradinski Buk, which is the longest waterfall on the Krka. With the submerged part of the mouth, the Krka is approximately 72.5 km long and is the 22nd longest river in Croatia.

From the Krka National Park, the Krka river flows into the sea at the Skradin, and further on it flows all the way to the famous shellfish farm located under the Šibenik bridge. With the further flow of the Krka, a river flows into the Adriatic Sea in front of Šibenik and forms an estuary in the channel of St. Ante. In estuaries, due to the mixing of salt and freshwater, the freshwater of the Krka River slides above the saltwater layer. In this type of area, salinity level is harder to define precisely, and a higher salinity ratio can affect the biological and agricultural development of the region

The water level and the total amount of accumulated water in the channel are crucial data for shellfish farmers near Šibenik. The strategic study of the City of Šibenik “Resource Mapping and Sustainable Management of the Mariculture Sector in Šibenik-Knin County” defines numerical models for shellfish farming. An important condition in modeling scenarios for rational production is the inflow of fresh water that has nutritive salts and can lower the seawater salinity. Regulation of shell salinity has a significant impact on the amount of produced meat and shellfish growth. Relevant data of water level in the channel and the amount of freshwater in the channel represents a great value to shellfish farmers in order to take timely protective precaution measures and to take care of the ideal level of salinity.

The Šibenik county area represents great importance in the segment of various maritime studies. The two main reasons why this county is a special area of interest is because there are Krka national park and the St.Ante channel. Current hydrology and biological studies are being conducted in the areas of brackish water and other potential environmental sea incidents.

The Ruđer Bošković Institute has a subsidiary in the Šibenik and they are conducting a different type of sea measurements to get the relevant data. As a part of the PEPSEA project (Protecting the Enclosed Parts of the Sea in the Adriatic from Pollution), together with the University of Zadar and the Šibenik city, they have procured tide gauge equipment from Geolux. The goal of the project is to develop a higher level of security solution for the protection of the sea and the coast from environmental pollution.

After following demo testing, they have decided to choose Geolux because of technical specifications. Besides specifications, Geolux was chosen because their equipment is easy to install and maintain. As a partner, they have decided to choose Geolux, which with its many years of experience in non-contact and advanced measurement technology has been recognized as an ideal partner for this project. Since there was no solid structure directly above the spot, Geolux had to mount a station on the pier using the tide gauge as a solid structure. As part of the tide gauge, level and surface velocity sensors were installed to measure sea level and water flow (discharge). Geolux has drilled a few holes on the stone wall where the pier is located to place an extended arm with the aim to connect it with the Datalogger, camera, and solar panel. A cable with stone weights was placed on the extended arm where the sensors are located, on which are sensors for measuring the temperature. It is possible to determine in real-time how much freshwater is in the channel. To prevent cables from salt intrusion, cables from the extended arm and junction box were protected with safety channels. At depths of 0.5m, 1m, 2m and 4m, sensors were installed in order to obtain relevant data of the salinity from several seawater layers. This is especially important for shellfish farmers that are located near the channel.

One of the biggest problems that can occur are the prediction of weather and wave heights affecting ship hydrodynamics. The St.Ante channel is the busiest channel in terms of fluctuated ships on the Croatian Adriatic sea during the summer season. The statistical calculation with the variables of the occurrence frequency of wave heights and the period of waves can determine the probability if there will be a storm or high waves in a certain period of time. The Maritime Meteorological Center receives data from local areas, including all data collected from tide gauges in the St.Ante channel during measurements to provide weather forecasts to the sailors and ship owners.

The channel is very important for the entire Croatian Adriatic coast because it is the busiest waterway during the summer season. The St. Ante channel can be dangerous for ships, especially smaller size ships because some winds can appear suddenly and have fatal consequences for boats and the whole Šibenik ecosystem. This event would result in oil leakage and extinction of a large number of plant and animal species if the oil leakage appears in the Krka National Park. By measuring the direction of flow and the speed of water flow on the surface, it is possible to plan the defense mechanisms against the spread of oil slicks, as well as the management of emergency services in crisis situations if there occurs an oil spill.

The measured data from the tide gauge in the channel proved to be accurate without any anomaly in measurement readings. The sensors and equipment that were mounted on the pier were not destroyed or even damaged due to weather conditions at sea. Collaboration on such a project is an example of how Geolux, with its knowledge and products, has proven to be a reliable partner who understands the complexity of various situations and can develop the best custom solution for different types of terrain.