Flood protection

Flood protection has been the focus of VOP Dolní Bousov's activities for many years. An independent flood protection company branch has been established to implement VOP's mobile flood barrier system development and manufacturing programme. Currently, this section provides comprehensive flood protection services. This primarily includes land profile studies, proposals for appropriate flood protection systems and provisions, manufacture of individual flood barrier systems to match customer-specific situations, development of the planning and implementation document folders, training of managers, and many other activities.

Mobile flood barrier system

Mobile flood barriers are technical preventive systems which can help to efficiently eliminate or substantially reduce the impact of floods. This mobile flood protection system is designed to direct the water flow, divert a flood wave or prevent water from penetrating into a building. The entire system is designed and built so as to maximise the efficiency of this direct flood protection tool, while satisfying the requirement for simple, straightforward and rapid erection respecting the specific nature and profile of the surrounding ground. The system is fully mobile and can be transferred as is from one site to another and erected without any previous preparatory works.
The basic barrier heights of this system are from 0.5 m to 1.5 m. It is an advantage of the system that no substructure is needed to support it and the structure is easy to transfer – it is actually portable, and thus a few trained people can erect the barrier at any length on any ground, even if the ground is soggy and prevents the use of machinery.

All parts are hand-portable to facilitate barrier assembly as much as possible. The barrier members are very easy and intuitive to handle. VOP Dolní Bousov's mobile flood barriers are virtually maintenance-free: it will suffice to rinse them with running water after use.

The system can also be used to increase the height of existing dams. Outstanding results have been obtained with this system during tests in artificial as well as actual conditions (impacts by various floating objects such as logs or cars: the high wave test, spill-over test and surf test to examine any displacement, deflection, leak or deformation of the barrier). Barrier resistance to mechanical impacts of big objects as well as to high waves and spills is the system's most important feature. In fact, impacts by floating objects are the most frequent cause of damage for various flood barrier systems in actual flood situations. We can proudly announce that in this respect our flood barrier satisfies, and even appreciably exceeds in some aspects, the requirements of the stringent US Army standards.

The glass-fibre reinforced plastic boards in the barrier possess high strength parameters, and at the same time, the material composition can be modified to satisfy the customer's need or wish (e.g. the need for enhanced resistance to ice, sludge streams or stone streams, etc.). The size of the glass-fibre reinforced plastic boards can be modified where needed, especially in view of their dual use – either as members of the mobile flood barrier (inclined and vertical structures) or as elements of stand-alone building protection systems. All of the components are easy to store and transport. Their sizes allow them to be accommodated in standardised containers, on pallets, trucks and freight wagons.

Mobile flood barrier system components

1. Glass fibre reinforced plastic boards

The boards are made of a specific glass fibre reinforced plastic which is resistant to extreme temperatures (from -30°C to +50°C) and chemicals, is harmless to health, and is dimensionally and structurally stable. They are manufactured in three basic standard sizes: 2,300 mm x 1,450 mm, 3,000 mm x 725 mm, and 2,000 mm x 2,300 mm. A barrier involving the 3,000 mm x 725 mm boards will be efficient against a 0.5 m water level height; the 2,300 mm x 1,450 mm board will retain water 1 m high; and the 2,000 mm x 2,300 mm will resist water 1.5 m high. The board lifetime is virtually unlimited (unless subject to mechanical damage). The high board strength against the pressure of water, mud, stones or other mechanical damage is achieved by technological means and by the complex material structure and sophisticated manufacturing processes. Furthermore, the reverse board side is fitted with reinforcing ribs to enhance the board's resistance to the continuously increasing hydrostatic water pressure. A sealing strip is riveted to the board bottom to make it leakproof at the interface with the ground and to level off uneven ground. So the strip restricts water leakage between the board and the ground as much as possible. To facilitate handling, the board is equipped with textile loops in the top corners.

2. Folding supporting structure

The structure is welded from steel sections (tube, "jäkl" rectangular cross section profiles, profiled sheets) and the bottom of the supporting tube structure is provided with steel spikes to prevent the structure from slipping on the ground. The top of the tube structure is fitted with sliding feet to level off the effect of the uneven ground with respect to the flood board. This structure can be erected on soft grounds (with vegetation) as well as on solid surfaces such as asphalt, pavement and concrete panels. The whole structure is hot-dip galvanised. The boards of the system designed for 0.5 m water level may be fixed to a supporting structure to form an integral unit.

3. Connecting pieces

The main connecting piece is composed of a steel sheet, a "jäkl" section, galvanised sheet, and a sealing strip. To enable this part to be pushed on between the boards (which are at least 5 cm apart), a "jäkl" section, defining the distance between the parts, is welded between the top and bottom steel sheets. This assembly is covered with a sealing strip, which protrudes on the bottom as far as the sealing strip on the flood boards. In addition, the top of this strip is fastened with the galvanised sheet, the shape of which enables sealing off the connection. In order to facilitate the assembly operation, (sliding onto/out of the boards), this connecting part is fitted with a handle on the reverse side. All steel parts of this component are galvanised. This connecting part assembly serves to combine and seal the boards and to prevent water leakage as much as possible.

Flood protection of buildings, other structures and land areas

The VOP Dolní Bousov's flood barrier manufacturing programme is also aimed at individual protection of buildings, other facilities and land areas, with focus on prevention of water ingress through doors, windows, garages, and other openings. This protection system is largely composed of a glass-fibre-reinforced plastic board with fastening points and elements. For the system to perform well, the ground must be adequately prepared and anchoring elements must be individually designed and installed on-site.

Advantages of the individual flood protection systems:

Easy handling and rapid assembly/disassembly (within minutes): the barriers are largely designed so as to enable it to be assembled by one person
Low sanitation requirements: it is sufficient to rinse the barrier with water with a disinfectant after use
Easy storage: the barriers can be simply stored in a garage or in a garden shed

Long lifetime (decades): the barrier will withstand harsh weather and chemicals. It helps very much if the barrier is stored properly when not in use
The barrier is resistant to impact from heavy objects (such as logs)

Development of flood plans and digital flood plans

Flood plans are process and activity planning documents helping the users – managers responsible for flood protection, flood committees, etc. – prevent the serious impacts of a flood and/or manage an existing flood within the person's scope of authority. Plans are structured so as to facilitate easy use of each document. The activities before, during and after a flood are described step by step, accompanied by photographs, sketches, maps and notes relating to the area affected.

A plan contains factual information on floods, photographs of the (potentially) flooded area, detailed information on the area, list of watercourses, dams and reservoirs, contacts to relevant individuals and organisations, information on material and technical assistance available, structured recommended tasks and assignments before, during and after a flood based on inspection of the area and assessment of available information.
Flood plan development includes local area reconnaissance survey, taking photographs and potential risk assessment. Critical sites, flood situation monitoring sites, and endangered structures are identified during the survey. Critical sites are sites that may aggravate the flood situation, such as bridges and footbridges and hazardous river beds. Monitoring sites are sites where marks are provided in well-visible and well-accessible points showing the water level and serving as the basis for determining the flood alarm category. The sites are registered by the person developing the flood plan.
In addition to the flood plan, the user will obtain supplementary materials such as a flood log or samples of flood alarm category announcements. How to use those supporting documents is described in the flood plan.
Once developed, the flood plan is transformed into digital format, which is interfaced to sensors (level indicators and rain gauges) and the local broadcasting facility. A digital flood plan is interconnected in all parts. The main purpose of a digital plan is to provide rapid and simple access to information when a flood alarm of one of the 3 categories is announced. The textual part is linked to map documents, a contact table and data sent to the control centre by the gauge indicators. Through another application the owner is able, virtually instantaneously, to announce a message on local radio without having direct access to it. This may be beneficial during evacuation, warning and other activities of the flood committee.

Once both the conventional flood plan and the digital flood plan have been developed, training (theoretical as well as practical) is provided to the flood committee. Practical training serves to explain all issues that remained unclear and to ensure that the flood plan will be appropriately used in an actual flood situation. VOP Dolní Bousov is an accredited educational body (accreditation granted by the Czech Ministry of the Interior).

Other activities of the Flood Protection Section staff include, for instance, detailed on-site flood inspections, development of flood reports, etc.