Spatial Adaptive Policy Pathways for rainwater resilient spatial redesign for urban areas

Abstract

In this research, the use of spatially applied adaptive pathways for rainwater resilient redesign of urban areas is investigated. It is explored how adaptive pathways can contribute to the integration of the climate stress of pluvial flooding in the planning process for the redesign of existing urban areas. This is done by developing adaptive pathways for the rainwater resilient design for a case-study in Amsterdam and evaluating their possible contribution to the planning process for redesign in general and specifically in Amsterdam.

The use of spatially applied adaptive pathways for rainwater resilience was explored by first developing pathways for a redesign for a case study in Amsterdam, the neighbourhood Bosleeuw, following the Dynamic Adaptive Policy Pathways (DAPP) approach. It was found that when considering pluvial flooding as the system stressor, the number of parallel design alternatives that could be included in the map are limited because rainwater resilience is considered at neighbourhood scale. Moreover, the shortage of the rainwater storage capacity in the current situation compared to the set objective for 2050 results in the inability to express the adaptation tipping points in terms of storage capacity and a sell-by date in terms of time. In addition, because of the number and size of the required measures to reach the objective for rainwater resilience in Amsterdam, the need to consider the implementation time in the adaptive pathways arose, to ensure the feasibility of the proposed pathways.

To this end, a set of modifications were made to the set-up of the pathways for a single design alternative, that enhanced the functionality of the pathways to illustrate the feasibility of the implementation of a solution. The results showed that the modified pathway set-up enable the incorporation of the implementation time of measures, the definition of adaptation tipping points and their sell-by dates and reviewing the effect of partially implemented measures combined.
These functionalities are demonstrated by developing pathways for the implementation of the redesign for the case-study under the temporal limit of the renewal strategy in Amsterdam: the strategy to plan all projects in the public space simultaneously and at the moment of planned maintenance or renewal of infrastructure. The results show that the modified set-up of the pathways enable the visualization and comparison of different implementation strategies and allow for the back casting of required actions to attain a set objective, without going into time-consuming or incomprehensible detail. However, the beneficial feature of the DAPP approach to postpone decisions to the future by reviewing parallel solutions and keeping future options open, is eliminated in the modified set-up, that reviews the implementation of a single solution. Similarly, the focus on the duration of implementation time and the consideration of actions in a timeline reduced the feature of the DAPP approach to express moments of decision and action in terms of how far the uncertain development has progressed rather than in time, which is a key attribute of allowing uncertainty in decision-making and design. The modified pathway set-up presented in this research, therefore, should be considered as complementary to the DAPP approach rather than a replacement. Overall, it is concluded that the adaptive pathways can contribute to rainwater resilience planning by providing a guiding spatial and temporal overview of required actions to support decision-making and the monitoring of adequate implementation of spatial adaptations.