Climate Change Adaptation Through the Use of Captured Urban Streams Supported by Nature-Based Stormwater Management

SUPERVISOR: Thomas ERTL

PROJECT ASSIGNED TO: Philipp STERN 

The frequent occurrence of extreme outdoor temperatures and heavy rainfall events increase the necessity for urban outdoor spaces resilient against climate change. The decoupling and use of captured urban streams supported by nature-based stormwater management bear a climate-effective and socially inclusive potential to contribute to the Austrian climate change adaptation strategy. ^[1]

Main Objective

The potential of decoupling captured urban streams from the combined sewer system for climate change adaptation measures will be investigated. A method to pre-assess the hydrological potential of remaining urban streams and the microclimatic sensibility in the formerly traversed region is being developed. It is then applied to selected case studies situated in the western region of Vienna. In the provisioned model region vulnerable population^[2] as well as dense building structure with high risk of overheating match with the hinterland of captured streams (Wienerwaldbäche).

Research Questions

1. How can most promising sites for climate change adaptation measures be detected regarding their hydrological potential and microclimatic sensitivity?
A method for the pre-assessment of captured urban streams and their suitability for climate change adaptation, for the case study of the captured streams, Wienerwaldbäche, is being developed. Data of available stream water as wells as locally harvested rainwater is being collected. The pre-assessment also seeks to identify sites where the necessity of climate change adaptation measures is highest. This includes the consideration of the description of the built environment such as green space availability and building densities as well as demographic values like population density.

2. How can pre-selected sites be compared in terms of their potential and demand for climate mitigating measures?
The proposed method and its assessment criteria is being developed further. Several urban morphological typologies along the captured urban streams are being created. Their climate mitigation potential as well as their demand for the implementation of blue green infrastructures is being assessed in detail and for each typology. This approach ensures the transferability of results and allows the detailed assessment of numerous potential sites.

3. How should a successful holistic planning and modelling approach which includes stakeholder involvement and water sensitive urban design be developed?
The integrated planning process is being developed alongside work packages (1) and (2) and enriched by stakeholder participation methods. The complex undertaking of implementing blue green infrastructures in urban context will be analysed and learnings for successful future ventures derived and documented.

Connections to the HR21 Research Clusters

Captured urban streams are the result of heavily colonising interventions[3], in the case of the Wienerwaldbäche, over the timespan of centuries. The investigation of decoupling such streams from the sewer system and re-connecting them to the urban environment exemplarily lays bare aspects of hydrological, socio-economic, and landscape connectivity in a specific urban context and therefore directly contributes to the HR21 research cluster “connectivity”.

The process of holistic planning and modelling for decoupling captured urban streams for urban climate change adaptation is based on the investigation of a variety of spatial aspects, such as proactive and reactive management processes (e.g., urban heat island mitigation plans), as well as formal and informal multilevel governance (e.g., city planning, stakeholder integration processes). The outcomes of this investigation are strongly connected and provide input to the HR21 research cluster “governance and planning”.