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Preservation of evidence / water law construction supervision

since 2016 Supervision under the Water Act: Bti application in the floodplains of Morava and Thaya

Bti (Bacillus thuringiensis israelensis) has been applied againts mosquitoes (Culicidae) in the floodplains of Morava and Thaya since several years. In case of extensive flooding this is not possible from the ground by using backpack sprayers but from the air by using helicopeters. This required a permit under the Water Law. The supervision required by the permit is done by DWS Hydro-Ecology.

Client: Gelsenverein March-Thaya-Auen (according to the permit under the Water Law)

since 2015 Water surveillance via online probes

Since 2015 measuring stations have been installed in some stagnant waters in cooperation with TBS waterconsult.

The measurement stations are provided with a multiparameter measuring sensor which continuously captures data like physical-chemical parameters (temperature, conductivity, pH, oxygen concentration). The data are sent to a data logger. The results are transmitted to an internet portal via SIM card and can be retrieved there in the form of continuously updated graphics. If the online monitoring is coupled with a control module, the deep water aeration system can be regulated in an cost-efficient way. In combination with a time-controlled winch, depth profiles can also be measured.

In cooperation with: TBS waterconsult (Link)

since 2001 monitoring of the dotation Obere Lobau

Due to the Danube regulation at the end of the 19th century, the oxbow system of the Upper and Lower Lobau was largely separated from the main stream. A connection of the Lobau exists only at the Schönauer Schlitz. Therefore water bodies of the Upper Lobau are connected solely when major flood events take place and only by back-stagnant water from the Lower Lobau. In order to counteract the eutrophication of surface waters and to raise groundwater levels here, the city of Vienna MA45 has been operating the ‘Dotation Obere Lobau’ project since 2002. Water from the New or Old Danube is introduced into the oxbow system of the Upper Lobau. If the limits of the water levels in the surface waters and in the groundwater are decent or if the water quality of the donor water bodies is sufficient, the dotation can take place from March to October.

Contribution of DWS Hydro-Ökologie: waterlaw application (Limnologische Betriebsordnung), limnological monitoring of the Upper and Lower Lobau and threshold control of the donor water bodies (nutrient chemistry, phytoplankton)

In cooperation with: University of Vienna IFÖN, Gruppe Wasser, Systema GmbH, IFUM-Wien

Client: city of Vienna MA 45

since 2000 Limnological monitoring of the New Danube

The construction of the power plant Freudenau caused fundamental hydrological, chemical and biological modifications of the New Danube. Nowadays this 20 km long river, which has originally been designed as a discharge channel, is extensively used for bathing and other outdoor pursuits. Since 2000 DWS Hydro-Ecology is examining the limnological development of the New Danube. This monitoring is conducted monthly or even every second week and includes hydrochemical analyses of the waterquality as well as biological analyses of the pelagic biocenosis.

Tasks: ecological overall coordination, chemical and biological analytics, ecological evaluation, material balance and trophy prognosis
Client: city of Vienna MA45, Verbund Hydro Power

since 1998 Investigations of impacts of sewage treatment plants in rivers

The ecological functioning of waterbodies describes their causal network between habitat and its organismic colonization. The use of water, for example for the discharge of waste water, should be in line with the ecological functioning. DWS Hydro-Ökologie is a reliable partner for wastewater treatment associations and municipalities in the field of outsourcing, as it investigates the influence of the waste water discharge on the biological quality elements (macrozoobenthos and phytobenthos) as well as the chemical-physical parameters according to the specifications of the quality target regulation.

since 1997 Revitalisation and limnological monitoring of the Kahrteich (Wiener Neudorf)

Qualitative and quantitative changes in the groundwater inflow, intensive bathing as well as intensive fishing were probably the causes of eutrophication in the Kahrteich near Wiener Neudorf. First measurements in 1997 showed that in summer the deep water was oxygen free. High ammonium and orthophosphate levels above the sediment and the distinct smell of hydrogen sulfide were causally related to the reducing conditions. As progressive eutrophication would have caused significant damage to fish fauna (including fish mortality) and bathing quality, countermeasures were taken early by the municipality as in autumn 1999 a deep water aeration system was installed. Since then, regular on-site monitoring has been supported by continuous measurements via online probes.

Tasks: Morphometric survey, mapping of sediment thicknesses and estimation of sediment cubatures, physico-chemical measurements in the depth profile and nutrient chemical analyses, zooplankton and phytoplankton surveys, trophic indication based on chironomids, manangement recommendations, water law submission, installation of deep water aeration, monitoring

In cooperation with: Polyplan, TB Schuster and the diving club Wiener Neudorf

Clients: Municipality of Wiener Neudorf

2019-2020 Preservation of evidence during the renaturation of salt pans in the Seewinkel area

Numerous salt pans in the Seewinkel area show massive changes since years and have often lost their typical fauna and flora. One of the causes lies in hydrological interventions in the sensitive groundwater regime due to unregulated endowment by hunters. The aim of the renaturation project is to carry out a field test on six salt pans near Apetlon by backwatering drainage ditches. Chemistry, soil structure, vegetation and aquatic settlement are documented.

Contribition of DWS Hydro-Ecology: Sampling, data analysis, technical report

Client: Arbeitsgemeinschaft Natürliche Ressourcen (AGN)

2011, 2012, 2015 and 2016 consulting and monitoring of the landscape pond Seestadt Aspern

Urban waters are of particular importance because of their value as a recreational area for the population. Morphology, hydrology and nutrient inputs affect functional biotic loops, which in turn dampen or accelerate internal fluxes. When a new water body is artificially created, a prediction for its development can be made if general conditions as well as aquatic ecological principles are taken into account. Optimal planning can ideally create a water body with a low trophic level and a low eutrophication potential.

In the master plan “Flugfeld Aspern” a park with an open water surface had been planned as a structure-forming element in the middle of the building area. From 2010 to 2014, the approx. 5 ha large, groundwater-fed pond was converted into the future urban district “Seestadt Aspern”.

Tasks: Consulting during the planning phase, water ecological monitoring after construction of the pond (nutrient chemistry, phytoplankton)

Client: City of Vienna MA45

2004–2007 Fish-ecological monitoring in the EU LIFE project „Lafnitz”

The aim of this LIFE project was to restore the continuum of the Lafnitz river from its source to its estuary. Over a period of four years, the hydraulic engineering departments of the Styrian and Burgenland administration erected several fish passes, which had previously been obstacles to the migration of fish.

Contribution of DWS Hydro-Ecology (formerly Donabaum & Wolfram): Fish ecological accompanying investigations (electro-fishing, fish pass controls, evaluation), in co-operation with G. Woschitz
Client: Weideverein Ramsargebiet Lafnitztal

2006 Technical expertise on a brine-shear at the Hallstätter See

After an accident in the salt mine of Hallstatt, a large amount of brine flowed into the Hallstätter See. The impact on the lake was investigated by the Bundesamt für Wasserwirtschaft in cooperation with DWS Hydro-Ecology (formerly Donabaum & Wolfram).

Tasks: Field work, sampling of the profundal zone, laboratory analysis of the macrozoobenthos, expert report
Client: Bundesamt für Wasserwirtschaft, Institut für Gewässerökologie, Fischereibiologie und Seenkunde

2006 Monitoring of cooling water discharge into the Danube River in Vienna

Rising temperatures resulting from global warming as well as discharges of cooling water are a significant risk for rivers. Over several years, DWS Hydro-Ecology investigated possible impacts from cooling water on the macrozoobenthos of the Danube River and abjacent oxbows lakes in the Lobau floodplain.

Client: Wienstrom GmbH

2004–2006 Limnological monitoring for the waster water treatment plant of Vienna

The main sewage treatment plant (WWTP) of Vienna was expanded in 2005. Every day, up to 18 m³ of wastewater are treated and discharged into the Danube Canal. The aim of the project was to evaluate the impact of the treated wastewater on the macrozoobenthos of the Danube Canal and the Danube before and after the extension of the WWTP.

Contribution of DWS Hydro-Ecology: Sampling, laboratory analyses, assessment and expert report
Client: Univ.-Prof. Mag. Dr. Uwe Humpesch

2003 Expertise on the flow and oxygen conditions in the marina Jois

under construction…

2001 Chemical-biological preservation of evidence of Kobersdorfer Mühlbach before the construction of the forest spa Kobersdorf

under construction…

1997 Evaluation of the effects of groundwater abstraction on the limnology of a groundwater lake

under construction…