Component B
In its part relating to the Modernization of the Wrocław Floodway System (WFS), the Project involved reconstruction and improvements of flood defenses in the city of Wrocław. It was designed to improve flood safety for the areas located in the city of Wrocław as well as for towns and villages situated in its immediate vicinity.
Until December 31, 2017 two Implementing Agencies: the Regional Water Management Authority in Wrocław and the Lower Silesian Board for Amelioration and Hydraulic Structures (DZMiUW), were responsible for the Modernization of the Wrocław Floodway System. Since January 1, 2018 the SWH PW Regional Water Management Authority in Wrocław was responsible for these project activities.
The works carried out as part of the Modernization of the Wrocław Floodway System were divided into three subcomponents:
Subcomponent B1
REHABILITATION OF LEVEES & CHANNEL PROTECTION
During the period 2012-2014, four works contracts were carried out related to the improvements/construction of flood embankments in Wrocław itself and its area. Under Component B1, 59.74 km of flood embankments were improved, including the (re)construction of associated infrastructure, i.e. culverts, embankment crossings, slope stairs, and different types of seepage barriers, from bentonite matting through sheet pile cut-off walls to slurry cut-off walls. An essential element was also the construction of service roads which allow ongoing maintenance of the structures to be provided, including efficient access during flood rescue operations, and which have been made available to the general public (gravel surface roads).
Subcomponent B2
RETAINING WALLS, CHANNEL WIDENING, HYDRAULIC STRUCTURES
In 2012 four works contracts were completed. 37.5 km of the Odra River and the Wrocław Floodway System channels were improved in order to adapt them to the conveyance of flood water. Five fish passes were constructed or rehabilitated in order to increase the Floodway System’s capacity for migration of diadromous fish.
Subcomponent B3
WIDAWA CHANNEL IMPROVEMENTS
Component B3 involved improvements to the Widawa River valley in order to adapt it to the controlled conveyance of a flood wave with a flow rate of 300m3/s as a result of transfer of excess flood water flowing through the Odra valley. A flood wave reaching Wrocław with a flow rate of 3100m3/s is divided into two parts at the Bartoszowice barrage. 2800m3/s flows through the valley of the Odra River along its channels, while 300m3/s through the Widawa River valley (a bypass). Flood waters merge again downstream of the city. During the period 2014-2018, two works contracts were carried out in the Widawa River valley which covered the section from the river’s mouth to km 21+500 within the area of the city of Wrocław and in the neighboring municipalities. Under Component B3, 41.4 km of flood embankments were constructed, including (re)construction of associated infrastructure, i.e. culverts, embankment crossings, slope stairs, and different types of seepage barriers, from bentonite matting through sheet pile cut-off walls to slurry cut-off walls. An essential element was also the construction of service roads which allow ongoing maintenance of the structures to be provided, including efficient access during flood rescue operations, and which have been made available to the general public (gravel surface roads).
The modernization of the WFS increased its flood carrying capacity from 2,200m3/s to the Qk value of slightly more than 3,100 m3/s, (i.e. a flood wave reduced by the Racibórz dry polder which reaches Wrocław), thus ensuring safe, in accordance with the current technical requirements, conveyance of high flows (comparable to the flood of 1997— a thousand-year flood), without damage done to local residents and facilities.
The Wrocław Floodway System is the largest system of waterways and hydraulic structures in Poland and one of the largest in Europe which is located within the area of one urban agglomeration. It starts at 241.5 km of the Odra in the area of Blizanowice and ends at the Widawa River mouth at km 266.9. It is made up of a network of the Odra channels, distributaries, and branches that have a dense infrastructure of hydraulic facilities and structures used for flood control, navigation, and industrial purposes. The mouths of rivers such as the Oława, Ślęza, Bystrzyca, and Widawa are also located in this area.
