Identifying underground urban heat islands in Vienna using groundwater temperature measurements
C. Steiner (GBA), 18 August 2021
Field measurements for MUSE in the pilot area Vienna focused on the shallow groundwater body, which consists of gravelly river sediments, on the right side of the river Danube. There are many different anthropogenic heat sources expected in this urban environment. In order to increase the knowledge of possible urban heat islands in the pilot area, we conducted groundwater temperature measurements in eight boreholes. The selected boreholes are located in the vicinity downstream of large known groundwater heat exchangers. Goal was to demonstrate the impact of the systems to the groundwater temperature. An analysis of temperature time series in the city of Vienna revealed a mean annual temperature of around 13 °C. In three study sites (Erdberg, Prater and Praterstern), we intended to quantify the urban heat island effect compared to this overall value of Vienna. Figure 1 shows the location of the boreholes inside the pilot area of Vienna.
The investigated boreholes were equipped with in-house developed loggers to measure the groundwater temperature in multiple depths and water level data loggers (have a look at our measurement equipment here).
At Erdberg we focused on one large building, which uses a groundwater heat exchanger for heating and cooling as well as borehole heat exchangers. Here we saw a large impact in the close vicinity of around 200 m on the groundwater temperature (temperature increase of up to 3 °C) and even in 700 m away from the injection well, the groundwater temperature is still elevated of 1 °C. Over the year, the influence of the shallow geothermal energy (SGE) use is prevailing from May to October, as figure 2 shows.
In the area Prater the expectations of a large thermal plume caused by a groundwater heat exchanger using 150 l/s for the Economic University of Vienna were not fulfilled. The investigated boreholes are situated outside of the thermally influenced area. The groundwater temperatures in the area Praterstern show an impact of the metro line nearby, they are increased up to 2 °C compared to the mean groundwater temperature in Vienna.
Our field measurements show that anthropogenic heat sources influence the temperature very locally, and a dense monitoring network is necessary to identify and more accurately delimit urban heat islands. The follow-up project “Heat below the city” intends to create a temperature map with high resolution for the identification of underground urban heat islands in Vienna. Management plans can integrate this temperature map for an efficient use of groundwater for heating and cooling and furthermore to counteract even the development of urban heat islands by intensified use for heating.
Other MUSE Posts
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- MUSE pilot area activities – RESULTS – #8 Glasgow
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- MUSE pilot area activities – RESULTS – #6 Zagreb
- MUSE pilot area activities – RESULTS – #5 Girona
- MUSE pilot area activities – RESULTS – #4 Aarhus
- MUSE pilot area activities – RESULTS – #3 Zaragoza
- Interview with our MUSE team member from Croatia
- New MUSE leaflet about shallow geothermal energy published
- MUSE pilot area activities – RESULTS – #2 Linköping
- MUSE pilot area activities – RESULTS – #1 Ljubljana
- Brand-new MUSE results: Fact sheets on shallow geothermal energy concepts
- Explore the new MUSE YouTube channel
- MUSE co-organized the Shallow Geothermal Days 2020
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- MUSE – Geothermal heat pumps, a highly dynamic market in Europe!
- MUSE and the underground urban heat island effect
- MUSE – Open-loop systems requirements & advantages
- MUSE – Web-based information systems for shallow geothermal energy
- MUSE – Closed-loop systems requirements & advantages
- MUSE results published in Energy Policy
- MUSE – Differences between deep and shallow geothermal energy
- Legal framework, procedures and policies of shallow geothermal energy use in the EU and MUSE partner countries
- BBC article about MUSE activities in Cardiff
- Pilot area activities – #14 Assessment of shallow geothermal energy resources in Warsaw agglomeration, Poland
- Pilot area activities – #13 Geophysical survey and groundwater monitoring in Brussels, Belgium
- MUSE at “EGU2020: Sharing Geoscience Online” – Free online geoscience conference
- Pilot area activities – #12 Thermal groundwater use in the urbanized area of Zagreb, Croatia