Hidrológiai Közlöny, 2017 (97. évfolyam)
2017 / 3. szám - MANAGING ENVIRONMENTAL RISKS - FLOOD PROTECTION EXPERIENCES AND COOPERATION IN THE DANUBE RIVER BASIN - Gombás Károly - Balatonyi László: Extremities in winter season - outlook for mitigation measures
84 point all month long and were dropped below -20 - -23°C on the coldest mornings over snow covered territories. Water temperatures decreased very quickly due to typically low water levels across all rivers and the ice development was constant. It escalated to a 170 km continuous ice formation on the Danube River where the thickness reached four meters in some areas. Based on the trilateral treaty, Croatia and Serbia initialized the ice-breaking activities. The local authorities provided the contact and supply (Láng 2017). The operations took place on two locations for 17 days:- „Icebreaker XI.” and “Icebreaker VI.” ship couple were deployed to the section Dunaíöldvár-Vukovár. The most important task was to create a route through the ~10 km ice cover near Dalj (1348-1358 rkm).- „Széchenyi” flagship and the “Icebreaker VII.” ship couple was ordered the section Vukovar-Bel- grade to minimize the damages in ports, marines, The operation was successful and the problematic sections could have been broken through. However the work was exceptional because both ships had to cut themselves through the icefield from upstream. Cutting from upstream of the congested ice involves considerable risks as the ice has no place to clean behind the ship. It can slips back to the ship’s aft and closes her (as it happened with Jégtörő VI and VII as well). For successful crossing, it is necessary for the ships to keep moving in the ice and this requires „scrolling” ships. Without scrolling equipment it is impossible to cut through an ice-wall from upstream. It also became apparent that without the high-performance two-engine vessels the crossing would not have been possible. The ice breaking activity was necessary in order to stop the upraising of the water level due to the ice blockade. The elevated water levels could cause inundation or endanger assets in Croatia, Serbia and Hungary as well. The conditions were suitable to operate with the ships and available time frame was also enough, because no serious flooding appeared from upstream. The cooperation among the bridges etc. The main goal was opening of 80-100 m width channel on the jammed ice and keeping clean the opened channel. Icebreaker XI. and Széchenyi are stronger ships and they were the ones to go forward. Icebreaker VI. and VII. provided backup. The leading ship broke into the ice barricade twice, some 40 meters apart. Between the two entering the ship's waves broke the congested ice into pieces. The pieces were shredded further into smaller ones by the secondary unit, ensuring that the ice do not close the opened channel. The direction of the opened channel was chosen to follow the alignment of the fairway. In order to speed up our progress they tried to make the channel more narrow, but in that case the broken ice could not be able to flow away, closed it and they had to clean it repeatedly. The cleaned lane is visual from the stratosphere as it is shown on Picture 6. Hidrológiai Közlöny (Hungarian Journal of Hydrology) 2017. 97. évf. 3. sz. countries is a great example of efficient resource sharing for mutually understood purposes and jointly defined criteria based on legally binding agreements. BASIN WIDE PERSPECTIVES OF MITIGATION MEASURES The ice management in the Danube Basin is an important issue, but not all the countries have to face with equally severe consequences of the ice transport. The solidarity principle applies in the catchment as it is stated in the International Commission for the Protection of the Danube River (ICPDR) 1st Flood Risk Management Plan of the Danube Basin District (DFRMP) which was endorsed in 2016 by the Danube Ministers. The Annex-2 of the document is listing agreed project proposals. Among them there is one called DANICE - DANube river basin ICE conveyance investigation and icy flood management. The initiative aims to create Danube Basin Ice Management Plan and long-term ice-management initiative of the Danube Basin. It would reveal the actual ice situation of the basin and the probable effects of the ice conveyance. The project shall deliver national and basin-wide operative resource Picture 6. Satellite images of the Danube band at Dalj, 1358-1348 rkm (Source: U.S.G.S., Landsat, 2017)
