Integrating strategic planning of nature-based solutions into urban planning

Julie Skrydstrup*

*Corresponding author for this work

Research output: Book/ReportPh.D. thesisResearch

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Abstract

Climate change increases the frequency and intensity of extreme rainfall events, which, coupled with urbanization, increases the risk of urban pluvial flooding. The planning of urban flood adaptation and urban planning impact each other, but the two are often planned separately. This typically results in urban flood adaptation becoming a problem that has to be solved after urban development plans have been decided, which do not provide the most optimal solutions to the many stakeholders in urban areas. Flood adaptation through nature-based solutions (NBS) is expected to deliver multiple benefits to urban areas, and thus relevant for multiple stakeholders. It is important to communicate the benefits of NBS in monetary terms to stakeholders in order to provide a common language, and to be able to understand socio-economic trade-offs and build business cases for NBS. Many of the benefits associated with NBS are intangible, thus they have no markets and require resource-intensive valuation techniques associated with a lot of uncertainty. While organisations are encouraging cost-benefit analyses, intangible benefits are rarely included. Planning is further complicated by long planning horizons that are subject to changes over time related to climate change, population growth and urban development.
The overall objective of this PhD was to support strategic planning of NBS by integrating it into urban planning. Due to the multiple dimensions of complexity as explained above, the research spanned across several methodologies and scientific fields. The main research objectives included stakeholders and their planning objectives, the availability and applicability of non-market valuation studies, and the integration of cost-benefit analysis with uncertainty of the future as well as different stakeholder perspectives.
Social science techniques were used to identify stakeholders and their planning objectives in planning situations where urban flood adaptation interacts with urban planning. A structured literature screening was developed that utilised Danish planning journals to ensure practical relevance. Results from the literature screening were validated through three workshops with various stakeholders. Compared to existing research, a diverse overview of stakeholders and their connections to planning objectives were derived, including new stakeholders that have not previously been considered. In total, 14 stakeholders and their connections to 17 planning objectives were identified. Despite the Danish focus, results were found to be relevant in international contexts when compared to international literature. Typical decision-makers were, not surprisingly, water utilities and city planning departments of municipalities. Results suggested that these stakeholders were more familiar working with other identified stakeholders than each other.
Many planning objectives within welfare for citizens, such as recreation, mobility (travelling time and safety), and health related objectives were identified. The fact that many stakeholders are interested in these planning objectives, suggests that they should be considered in planning of NBS. However, valuation of these objectives often require non-market valuation techniques. A search in scientific literature, grey literature, existing databases, and decision-support tools investigated the availability of valuation studies. Most objectives within welfare for citizens and environmental protection could be monetised through primary valuation studies and decision support tools. Many of these are difficult to apply within the screening stages of planning as they depend on data that are hard to obtain and few are applicable for smaller NBS sizes in urban areas. Thus, a valuation study was conducted utilising values and information from 24 primary valuation studies. The focus was on the recreational value, since many stakeholders had an interest in this planning objective, and it is considered an important benefit in urban areas. A generic value and value transfer function were elicited, both requiring input data of population density and the size of the NBS area. These two types of data are typically available in a planning context and thus easy to use.
Cost-benefit analyses can evaluate the performance of NBS based on their ability to achieve stakeholder relevant planning objectives. For the first time, cost-benefit analysis was combined with scenario analysis and multiple stakeholder perspectives. Scenario analysis assesses the robustness of NBS performance over time across a set of likely future scenarios. The NBS performance across scenarios provide the uncertainty of performance. To account for different stakeholder perspectives, the concept of “decision lenses” was introduced that accounts for the fact that stakeholders have different decision opportunities. This combination was tested and exemplified through a case example, where results from the other research objectives were included. Results showed that the inclusion of stakeholders from the urban planning domain may very well reduce future uncertainty as well as reduce bias towards large structural measures. In general, results illustrated the potential in considering NBS strategies through different decision lenses to identify NBS strategies that accommodate several stakeholders.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages59
Publication statusPublished - 2021

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