Flooding of regulated riverbank: causes and protection solutions

Abstract

The river of Zrmanja is one of the largest in the south Croatian region of Dalmatia, characterized by a karst terrain. About 12 km upstream from the river mouth in the Adriatic Sea, it passes through the town of Obrovac, the most important and largest town in the Zrmanja area. About 5 km upstream from Obrovac, the HEPP Razovac with dam and retention regulates the river flow from the upstream and sea tides from downstream in the town. A gauging station is also located in the town, next to the downside of the main bridge. Both river banks in Obrovac are regulated, but the right bank is too low just upstream the bridge so it is sometimes flooded. The City government and the House of Culture are located there and in such circumstances they always suffer damages, especially in the last few years. Therefore, it is necessary to perform river reconstruction to protect these and neighboring objects from floods. The aim of this paper is to present hydrological and geotechnical conditions in Obrovac and suggest structural measures to raise flood protection. Respecting that, few solutions are prepared and will be presented with comparison at same technical level, including both advantages and disadvantages.