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Periodic river flooding, whether as a result of prolonged rainfall or spring thaw, is perfectly natural in our geographical area. Unfortunately, in the face of serious climate change, we are increasingly confronted with dangerous torrential rainfall that leads to more serious phenomena such as flooding. We therefore need specific solutions to increase the retention and use of rainwater.

  • What is flooding?
  • Climate change and human interference with water management
  • Flood risk management
  • Modern flood protection – HYDROZONE retention tanks
  • HYDROZONE – implementations and benefits

What is flooding?

According to the definition adopted by the Water Law, flooding is to be understood as the temporary covering by water of land that is not normally covered by water, in particular caused by the surge of water in natural watercourses, reservoirs, canals and from the sea, excluding the covering by water of land caused by the surge of water in sewerage systems[1].

In reality, it is one of the most dangerous and violent phenomena, with huge economic, environmental and even human losses.

Progress in reinforcing flood protection measures

Climate change and human interference in water management

According to UN data, natural disasters account for more than 90 per cent of all major recorded events, and of these, floods, inundation and waterlogging are responsible for more than 40 per cent of the damages[2]. These dangerous and catastrophic phenomena are the result of severe climate change, but also of an irrational human economy.

On one hand, climate change has resulted in prolonged periods of drought, but also in extreme events such as heavy torrential rainfall. On the other, the development of riverbeds and increasing areas of impermeable surfaces, such as concrete plazas, paved roads or buildings, do not allow rainwater to naturally infiltrate into groundwater. Instead, they run off at a rapid rate causing the water level of rivers or reservoirs to rise rapidly.


Flood risk management

Flood risk obviously cannot be eliminated, but we can manage flood risk. On 23 October 2007. The European Parliament adopted the Floods Directive[3], which requires Member States to take measures to reduce the risk of flooding.

In Poland, protection against flooding is the responsibility of the State Water Management Company Wody Polskie (PGW WP) as well as the central and local government authorities. In accordance with the Floods Directive and the Water Law Act, flood risk management plans as well as hazard maps and flood risk maps are prepared periodically to increase the safety of the Polish population.

It is also necessary to coordinate measures within entire catchments so that those taken in the upper part of the catchment, such as construction of dykes, do not increase flood risk in the lower part.

When planning such activities, it is extremely important to use solutions to increase natural retention and protect environmentally neutral ecosystems. Natural retention will not only allow excess water to be retained in the event of heavy rainfall, but also to be used in periods of prolonged drought.

HYDROZONE retention tank

Modern flood protection – HYDROZONE retention tanks

HYDROZONE systems from Ecol-Unicon are an innovative approach to the retention problem. The distinguishing feature of such solutions is their modular design and the possibility to freely configure equipment elements to meet the needs of rainwater and snowmelt pretreatment, retention and utilisation.

The stored and pretreated rainwater is reused to wash streets, car parks, water green areas or flush toilets. It can also be infiltrated into the ground, significantly reducing the costs associated with lost retention charges. Our range includes water retention systems to suit different needs, such as BASIC, CLEAN and BENEFIT.


HYDROZONE – tangible solutions and benefits

HYDROZONE BASIC tanks were used, among others, during the construction of the Hillwood Łódź Górna logistics centre located in the southern part of the city. The facility consists of a large area of roofs and sealed surfaces, which required an appropriate rainwater collection system. Water entering the retention tank is successively pumped out into the storm sewer system, which provides a backup for the capacity of the entire system.

Two tanks founded in Józefów Street in Łódź have a capacity of 1,500 m3 and a length of almost 70 m. In addition, they are equipped with a pumping station consisting of a chamber and modern water treatment devices.

The HYDROZONE BENEFIT system, on the other hand, has proved its worth in Międzywodzie, a small coastal town. For years, residents there have struggled to cope with the effects of torrential rainfall along the coast and droughts in the northern part of the town.

The system, with a capacity of 115 m3, provides storage for water from rainwater systems and, through the use of additional water treatment modules, allows it to be used for other purposes, such as watering greenery.

flood retention tanks

Implementation of the HYDROZONE BENEFIT tank and the BUMERANG SMART system in Międzywodzie


HYDROZONE BENEFIT was also used in the construction of a floodplain polder in Rawicz. A prefabricated reinforced concrete retention tank with a capacity of 550 m3 was used to temporarily collect rainwater fed by the planned canal at Kadecka Street. It consists of flat closing modules, an extension module, internal supports and covers

The system comprises of an integrated mineral suspended solids and oil derivatives separator and two pumping systems. The solution effectively relieved the pressure on the existing rainwater drainage system and dewatered the surrounding area.

In turn, HYDROZONE BENEFIT modular retention tanks with a capacity of 500 m3 in Gorzów Wielkopolski made it possible to eliminate local flooding in the area of Szarych Szeregów Street, Ogińskiego Street, Prądzyńskiego Street, Sosnkowskiego Street, Jarocki Street and Załuskich Street. They also made it possible to regulate the management of rainwater and snowmelt in the WS-1 catchment area in the Szmaragdowa Street.


The BUMERANG SMART system was used in all systems. This is an innovative solution for monitoring the operation of equipment and facilities in water and wastewater systems, and is an integral component of HYDROZONE tanks. It not only enables better management of rainwater retention and use, but also economical and efficient management of the operation of the entire water and sewage network.


[1] Act of 20 July 2017. Water Law (Article 16(43))

[2] Economic Losses, Poverty & Disasters 1998-2017

[3] Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007.