Abstract
Deltas and coastal cities around the world face the need to adapt to uncertain future changes. We compared adaptation planning on flood risk management in four cases based on three main elements of adaptive planning: to prepare for a wide range of plausible future scenarios; to respond to change with robust and flexible actions; and to monitor critical changes to be able to reassess the plan accordingly. Differences can be observed in the implementation of these elements. Good practices could be distinguished: cases consider a wide range of future scenarios; short-term decisions are coupled with long-term options while envisioning these options and possibilities for switching between them through adaptation pathways; opportunities originating from other agendas to achieve multiple objective investments are seized; and the system's resilience is improved by a wide variety of measures. At the same time some barriers for using adaptive planning approaches were identified: the use of a wide range of scenarios is only accepted in an exploratory phase of planning. Structural flood protection measures taken in the past do constrain future choices. The potential for monitoring and reassessment of options is hampered by the fact that trends in some variables cannot be detected.
Highlights
The world’s river deltas and coastal cities are increasingly vulnerable due to pressures from climate change, relative sea level rise, and population growth (Mulder et al ; Syvitski et al ; Vörösmarty ; Renaud et al )
In densely populated deltas and estuaries such as the lower Rhine delta in the Netherlands, the Thames estuary in the UK, the Hudson in New York, and the Ciliwung delta on Java (Indonesia), spatial planning is challenged to enable socioeconomic developments and well-designed water management to provide services such as flood risk management, fresh water supply, and good environmental conditions
Central elements of adaptive planning are (Sayers et al ): responses to changes are effective under the widest set of all plausible future scenarios; responses do not foreclose future options or unnecessarily constrain future choice; relevant changes are foreseen through targeted monitoring and scenarios of the future are continuously being reassessed; and policies, strategies, and structure plans are appropriately redefined
Summary
The world’s river deltas and coastal cities are increasingly vulnerable due to pressures from climate change, relative sea level rise, and population growth (Mulder et al ; Syvitski et al ; Vörösmarty ; Renaud et al ). Considerable efforts have been made to compare adaptation approaches among different areas in the world These comparisons focused on flood risk strategies (e.g. Wilby & Keenan ; Ward et al ), climate proofing of coastal cities (Aerts et al ), vulnerability and adaptive capacity of deltas (Bucx et al ), or deltaic tipping points (Kwadijk et al ; Renaud et al ). In this paper we expand on these previous studies by analyzing flood risk management policies and the related adaptation planning approaches applied to deal with uncertain future changes for four deltas and coastal cities in developed and developing countries. Central elements of adaptive planning are (Sayers et al ): responses to changes are effective under the widest set of all plausible future scenarios; responses do not foreclose future options or unnecessarily constrain future choice; relevant changes are foreseen through targeted monitoring and scenarios of the future are continuously being reassessed; and policies, strategies, and structure plans are appropriately redefined. Are the chosen approaches fit for purpose? What lessons can be learnt for application in other cases?
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