Urban Stormwater Management in the face of Extreme Events and Failure Incidents - Using Systems Thinking and Participatory Methods to Inform Management Decisions and Enhance Resilience

SUPERVISOR: Thomas ERTL

PROJECT ASSIGNED TO: Katharina KEARNEY 

Climate change and rapid urbanization are putting existing stormwater systems under pressure and increasing the risk of urban flood events, yet a lack of empirical data on stormwater infrastructure (SWI) responses to these developments makes it difficult for municipalities to take targeted and effective action in the form of protective measures and emergency response planning. The SWI in many cities is ageing, being augmented and expanded by above-ground, decentralized stormwater management solutions (Kleidorfer et al., 2019). The result is a complex heterogeneous system, the condition and extent of which is not always well known by system operators, local planners and government (Emanuelsson et al., 2014).

Extreme precipitation events that go beyond the capacity of a SWI will likely compromise its performance and/or result in the failure of said structure. Aside from technical factors like the design and dimensioning of SWI, human factors like management, operation and maintenance schemes play an important role in the ability of the urban system to absorb stressors like extreme hydrological events with minimal disruption and damage to society. Managing stormwater in urban areas is a multi- and transdisciplinary task, demanding coordinated efforts between many different stakeholders (private and public).    

Three central research questions are addressed in this thesis:

  • How does standard dimensioned stormwater infrastructure (SWI) respond to extreme events?
  • How can the resilience of different SWI types be assessed?
  • How can an incident management scheme and a communication strategy regarding such disturbances be developed?

The conceptual basis of this thesis is grounded in the notion of interconnections in complex, real-world systems – in this case, the hydrological and meteorological systems intersecting with the urban system, both technical and socio-economic dimensions. In line with this, the coupled socio-ecohydrological systems (SEHS) perspective taken by Hein et al. (2021) acknowledges that human and hydrological systems are inextricably linked and marked by continuous exchanges that alter system structure and influence system behavior.

Methodological approaches:

  1. Qualitative System Analysis:

    - Causal Loop Diagrams

    - Stakeholder workshops

    - Interactive mapping sessions

  2. Participatory modelling: Fuzzy Cognitive Mapping and System Dynamics models
  3. Failure Modes and Effects Analysis for individual infrastructures

The use of different participatory methods within this research project intends to expand the scope of stakeholders and informants involved in modelling and analyzing the wider stormwater management system, offering a framework for social learning and reframing approaches to urban water management. Within the context of this project there have been several workshops held in the case study town of Feldbach (Styria), as well as expert interviews and some initial group modelling sessions. The method of fuzzy cognitive mapping (FCM) was used to gather a diverse set of maps representing different views and understandings of the system and problem at hand.

The following connections to the HR21 Research Clusters have been identified:

  • Governance: policy and management issues at different scales are considered in the research relating to urban stormwater management, and the changing value base in society calls for new approaches like community driven ideas around the use of public space for climate adaptation. Engaging different stakeholders and offering an environment in which local actors can reflect on the dominant narratives behind flood management policies is a crucial step towards building resilience.
  • Vulnerability: vulnerability assessments must adequately account for dynamics and system responses. The research project at hand entails a descriptive analysis of the various failure modes and effects that can ensue as a result of different pressures and complex interactions within and between relevant stormwater management infrastructures. By examining individual infrastructure types within the local context, a richer picture of possible vulnerabilities in urban stormwater management systems can be achieved, and should help inform the decisions made under uncertain future demographic and climatic developments
  • Connectivity: Mapping out possible interactions and dynamics in a complex system of urban stormwater management infrastructure surrounded by other critical and settlement infrastructure is a key aim of this research project

This thesis is part of the BEJOND project, a cooperation between BOKU, Graz Technical University and the University of Innsbruck. The project was commissioned by the Austrian Federal Ministry of Agriculture, Regions and Tourism (BMLRT) and is co-financed by several Austrian Federal States. 

Emanuelsson, M. A. E. et al. (2014) ‘Flood risk assessment for infrastructure networks’, Journal of Flood Risk Management, 7(1), pp. 31–41. doi: 10.1111/jfr3.12028.

Hein, T. et al. (2021) ‘The coupled socio-ecohydrological evolution of river systems: Towards an integrative perspective of river systems in the 21st century’, Science of The Total Environment, 801, p. 149619. doi: 10.1016/j.scitotenv.2021.149619.

Kleidorfer, M. et al. (2019) ‘Leitfaden Regenwasserbewirtschaftung - Entwicklung flexibler Adaptierungskonzepte für die Siedlungsentwässerung der Zukunft – Praxisleitfaden aus dem Projekt Flexadapt’.