Lower Arturowek (AD)

Lower reservoir (AD): space area of 3.05 ha, capacity of 40 600 m3 and average depth of 1.33 m. It is the biggest of the three reservoirs and the biggest public and open bathing site with a sandy beach in Lodz.

Task: Construction of buffer vegetation zones in the spots of point rainwater inflow in order to reduce surface run-off; construction of buoyant vegetation mats.

Construction of buffer vegetation zones in the upper and middle reservoirs in the spots of point rainwater entry is to reduce inflow of pollution to the reservoir water. This will be accomplished by incorporating them in the vegetation structure, and adsorption taking place in the biogeochemical structure of the gabion zones. On the other hand, construction of a floating island with vegetation in the upper section of the AG reservoirs is also to provide habitats for zooplankton, which among its various functions performed for the reservoirs, reduces symptoms of eutrophication (cyanobacterial blooms). Removing a several centimetre thick layer of the bottom sediments will result in elimination of nutrients, thus it will reduce the process of internal supply.

Construction of buffer vegetation zones with a biogeochemical barrier involves combining hydrotechnical pre-treating equipment, i.e. a shallow tank and a lamella separator with biogeochemical elements comprising a gabion partition filled with dolomite or lime stones, and protected from the upper water with coconut and biological mats. Locating the crown of the partition 20 centimetres below the NWDL (normal water damming level) and forming a scarp on the outside of the gabion will facilitate growth of the water vegetation. In the upper section of the reservoir, planting the northern (sunlit) and southern (shaded) scarp of the reservoir with water vegetation (calamus, reed, Schoenoplectus lacustris, Iris pseudacorus L., Typha latifolia L., and Typha minima) and hedging vegetation, is to restrict access to the reservoir in order to limit feeding of water birds and reduce pollution entering its water with surface run-off.

Results: Removal of nutrients in the quantity of at least 2.5 kg/p.a. through the construction of the buffer zones and floating vegetation mats for Arturowek recreational reservoirs and reduction of the internal supply capacity by 20% achieved due to the removal of bottom sediments. 

Middle Arturowek (AŚ)

Middle reservoir (AŚ): space area of 2.58 ha (including an island with the space area of 0.03 ha), capacity of 34 900 m3 and average depth of 1.35 m. It is mainly designated for water sports.

Task: Construction of buffer vegetation zones in the spots of point rainwater inflow in order to reduce surface run-off, and construction of buoyant vegetation mats

A shallow tank and a lamella separator installed on the rainwater sewer which drains rainwater from the roof and grounds of “Prząśniczka” Leisure and Hotel Centre directly to Arturowek middle reservoir, are to eliminate suspension entering its water with surface run-off. Construction of a gabion partition at the outlet of the rainwater sewer filled with dolomite or lime stones, planted with water vegetation and protected from the upper water with a coconut mat is to reduce inflow of pollution to the reservoir water. This will be accomplished by incorporating them in the vegetation structure, and adsorption taking place within the biogeochemical structure of the gabion zones. Removal of a few centimetre thick layer of bottom sediments will result in eliminating nutrients, thus it will reduce the process of internal supply.

Four log-made partitions constructed on a ditch which seasonally drains surface water from the forest, are to slow down the surface water inflow to the reservoir, which will be accomplished by its retention leading to increased infiltration in the bottom of the rainwater sewer. Constructing the gabion partition filled with dolomite or lime stones protected from the upper water with a coconut mat and planted with water vegetation outside is to purify such water.

Arranging a 30 metre long hedge on the northern bank of the reservoir, directly above the sluice and damming structure, is to limit feeding of water birds, thus reduce pollution entering the reservoir with the feed. Additionally, the plants are to perform the function of a natural barrier preventing pollution inflow with surface water or wind.

Results: Removal of nutrients in the quantity of at least 2.5 kg/p.a. through construction of the buffer zones and floating vegetation mats for Arturowek recreational reservoirs, and reduction of the internal supply capacity by 20% achieved due to the removal of bottom sediments.

Upper Reservoir (AG)

Upper reservoir (AG) is the shallowest (0.93 m) of the three Arturowek reservoirs comprising the space area of 1.08 ha and capacity of 10 000 m3. It is a fishing site for anglers. The Polish Angling Society (Voivod’s Office in Lodz 1996) stocks it annually with fish, and currently this reservoir performs the function of a self-acting sedimentation tank.

Task: Transformation of the upper part of Arturowek upper reservoir’s bowl, which currently operates as a sedimentation tank within the sedimentation-biofiltration system.

Transformation of the reservoir, which is annually fish stocked by the Polish Angling Society and performs the role of the self-acting sedimentation tank which operates within the  sedimentation-biofiltration system will facilitate improvement of the water quality by eliminating suspension incoming with the Bzura water. The dedicated sedimentation tank for mineral suspension with biogeochemical (gabion partition filled with dolomite or lime stones protected from the upper water with a coconut mat) and biological (plantings of  calamus, reed, Schoenoplectus (Rchb.) Palla, Iris L. and Typha) zones is to reduce the inflow of pollution to the reservoir by settling it in the vegetation structure. Gaps between the gabions facilitate fish migrations. The bottom of the tank has been strengthened with reinforced concrete openwork panels arranged on geotextile material spread over 15 cm draining layer of gravel or sand and gravel mix. The site has also been equipped with a reinforced drive in the north-eastern section of the reservoir to facilitate removal of alluvial deposits.

The crown of the dike in the waterside zones has been lowered to enforce two-way movement of water.

Trees and shrubs overgrowing the edges in the upper section of the reservoir have been appropriately shaped in order to establish a natural barrier for reducing pollution entering its water with surface run-off.

Removal of a few centimetre thick layer of bottom sediments will result in eliminating nutrients, thus it will reduce the process of internal supply.

Results: Improved quality of water in the Upper Arturowek Reservoir by 20%, with a special emphasis placed on reducing the quantity of suspension and nutrients, achieved as a result of ecohydrological adaptation of the bowl in the upper section of this reservoir.

The Bzura River (BP, BW, W, SW)

The Bzura River (BP, BW, W) is the largest river in Lodzkie Region. It stream starts in an artificial pond at 32 Rogowska St. Its direct catchment of the head stretch holds forested areas, holiday centres, recreational allotments and single family housing. The Bzura is the left tributary of the Vistula, and its basin covers space area of 7788 km2 and length of 166 km, where 6.5 km of the river (8.85 km2 of the catchment area) is within the administrative borders of the city of Lodz. The catchment of the upper Bzura, above Lagiewnicka St. covers the space area of 6.41 km2. The Bzura’s demo stretch is 3.54 km long, where 56.6 % of this length is occupied by artificial reservoirs.

Pond at Wycieczkowa St. (SW) is situated on the right side of the Bzura’s bed, immediately below Wycieczkowa St., and it lacks direct connection with the river. 

Task: Construction of the biofiltration sequential system (BSS) on the Bzura above Arturowek reservoirs and below the outlet from rainwater sewage collector located at Wycieczkowa.

The local layer of rocks and a log-made structure on the stretch between “Upper Arturowek Reservoir” and Wycieczkowa St. (length of approx. 260 m) intensifies the process of meandering and strengthens self-purification capacity of the river. Arranging a watering hole for wild animals in the local depression of the river in the place of the extended riverbed provides natural nature to the ecosystem.

The bottom and scarp of the stream reinforced with the layer of rocks below Wycieczkowa St. prevent the process of washing out caused by intensive discharge of the river water due to torrential rains.

Construction of the biofiltration sequential system (BSS) and integrating it with the rainwater sewer from Wycieczkowa St. in the place of the existing non-drainage reservoir on the right bank of the Bzura, just below Wycieczkowa, facilitates reception and retention of rainwater waves and their pre-treatment in the natural biofiltration system. The processes of mechanical pre-treatment of rainwater running-off from Wycieczkowa take place in a swirl sedimentation trap with a lamella insert, and they significantly reduce the quantity of suspension introduced into the system. The tank is subdivided into 2 sections with a gabion partition filled with dolomite or lime stones protected from the upper water with a coconut mat:
- sedimentation section which covers approx. 1/3 of the surface – this is where mineral suspension is intercepted
- biofiltration section which covers the remaining 2/3 of the surface, and where floating water plants, duckweed in particular, will grow due to the low level of light

and it performs the role of the so-called bio-sedimentation tank. The bottom of the tank has been strengthened with reinforced concrete openwork panels arranged on geotextile material spread over 15 cm draining layer of gravel or sand and gravel mix. It will be regularly desludged to improve its efficiency.

Results: Improved quality of water from the rainwater outlet located at Wycieczkowa St. by 50%, particularly achieved by reducing the load of nutrients and suspension incoming to the Bzura as a result of construction of the biofiltration sequential system (BSS);

Ponds

Reservoir No. 7 owned by the University of Lodz (UL) and Reservoir No. 17 (BPW) located just above Wycieczkowa St. are within the cascade of 17 small reservoirs on the Bzura river between Strykowska and Wycieczkowa Streets. They are located on private land and mainly perform the landscape and retention-related function. The status of water in the cascade of the small retention reservoirs is unsatisfactory, and they require rehabilitation in order to restore their natural functions of pre-treating the Bzura water by implementing such measures as desludging, renovation of the damming structure, and plantings. Ecohydrological rehabilitation of the two reservoirs (one is in the middle section (UL), and the other (BPW) closes the system), and transforming them into a system of biofilters will efficiently intensify the self-purification process.

Task: ecohydrological adaptation of two out of 17 small artificial small retention reservoirs located on the Bzura and above Wycieczkowa Street, in terms of intensification of the river’s self-purification capacity and transforming them into the system of biofilters based on the principles of ecohydrology and phytoremediation.

Ecohydrological rehabilitation of the UL reservoir, which holds significant deposits of organic matter (leaves) involves desludging of its bottom with a layer of at least 30 cm, renovation of the scarps and modernisation of the sluice and damming structure. Construction of a gabion partition filled with dolomite or lime stones and protected from the upper water with a coconut mat represents a key element of adaptation of this reservoir. The partition will be built at the inlet to the reservoir, and it will perform the role of sedimentation tank for pollution (mineral suspension in particular) entering the reservoir. It will also prevent inflow of algae from a reservoir located above the UL reservoir, where cyanobacterial blooms have been observed each year. The crown of the partition located 20 centimetres below the NWDL (normal water damming level) and overgrown with water vegetation, facilitates a better efficiency of absorption of nutrients. 2 PVC pipes have been placed in the gabion partition, about 30 cm above the reservoir bottom, which enforce water circulation around the existing island in the northern section of the reservoir. In order to provide the reservoir with more light and reduce the risks posed by falling leaves, it is necessary to control the treestand regularly by cutting and/or trimming branches hanging directly above the reservoir.

Ecohydrological rehabilitation of the BPW reservoir involves desludging its bottom to remove nutrients thus limit the process of internal supply, and constructing a gabion partition at the inlet of the reservoir, which will be filled with dolomite or lime stones and protected from the upper water with a coconut fibre matt. A slot in the partition is to enforce circulation of the river water and direct it to the northern part of the reservoir whose surface in one third is overgrown with water plants. These plants contribute to additional cleaning of the water by using their capacity in terms of accumulation of pollutants.

Results:
Improved quality of the Bzura water below Wycieczkowa St. by 20% with a special emphasis placed on reduction of nutrients, which will be accomplished as a result of ecohydrological adaptation of the UL and BPW reservoirs.