Restoration works on the "Otok Virje" arm as part of the EU project "Drava Life"
Croatian Waters, Water Management Department for Mura and Upper Drava, in the role of lead partner and project owner, is implementing an EU project called "Drava Life - Integrated River Management". This LIFE project aims to encourage the practice of unconventional, innovative, modern and sustainable practices of integrated management of lowland rivers in Croatia and the region through examples of restoration along the Croatian course of the Drava River. The aim of the project is to achieve improvement of the ecological and morphological condition of the Drava River in Croatia at a total of 8 locations in 5 counties through mutual international and national cooperation of all stakeholders in the river area.
The project envisages the development and implementation of over 40 specific activities. One of the current activities is the restoration of a 1.35-kilometer-long branch and partial dismantling of the existing embankment on the right-bank inundation of the Drava River from river kilometer 312 to 314 in the settlement of Otok Virje, in the municipality of Cestica in Varaždin County.
The main purpose of this project is to bring water into the arm at lower river flows and to stimulate morphological and biological dynamics in the arm and in the main channel of the Drava, thus leaving the possibility of creating new habitats for birds on steep banks and sandbanks that will be formed between the arm and the main channel.
The arm "Otok Virje" is located in the Drava River area upstream of the reservoir of the Varaždin - Ormoško Lake HPP and the Otok Virje - Ormož road bridge. In its current state, the Drava arm is not connected to the river on its upstream side, but water occasionally enters it from the downstream side. The area covered is mainly covered with tall vegetation, with wider stretches of forest areas along the Drava River itself.
The arm is designed for 95% of the duration of the Drava water level, and the flow rate will depend on the operational operation of the Formin HPP in Slovenia and the Varaždin HPP in Croatia. The slopes of the branch are 1:2 and 1:4, the width of the bottom of the newly constructed riverbed is up to 11 m, and the amount of excavation is estimated at around 65,000 m3. The restoration of the branch will reduce the pressure of the Drava main stream on the left bank near Ormož, and will also increase the flow capacity in the event of floods and raise groundwater levels in floodplain forests.
Currently, about 600 meters of the new channel bed has been excavated, access roads are being established with excavated material and vegetation is being removed from the channel route, and the removal of the existing 300-meter-long embankment has recently begun. The stones from the embankment will be used to fix and protect the entrance to the channel. By April, or the end of the works, depending on the weather conditions on the ground, it is planned to build a biological hydraulic structure in the concave part of the channel to protect against accelerated erosion.