Claudia Katherine Nielsen

Exploring the nexus between sand, resilience, and disaster risk in urban regions exposed to natural hazards

Sand resources are the most consumed solid resource globally, and sustainable sand resource management is gaining interest worldwide due to the social and environmental consequences of increasing demand. Coastal regions face unique pressures on demand and changes to sediment availability that threaten the short- and long-term resilience of these regions. Urbanisation in coastal regions is increasing demand for development infrastructure, resilient flood protection, and new construction to address damage following disasters. Availability of sediment, terrestrial sand, and crushed rock, collectively referred to as sand resources, is foundational to construction material security; these are the key ingredients in concrete, asphalt, and glass. In coastal regions, sediments also play an important role in maintaining land area and natural flood protection; however, human presence in these regions is altering natural sediment transport dynamics. This increases the impact of flooding, while anthropogenic climate change further intensifies coastal hazards and exacerbates land loss. These compounding risks threaten the ability of coastal urban regions to continue providing resilient infrastructure which meets the needs of expanding cities without causing negative environmental consequences.

This dissertation uses a nexus approach to centre sand resources within disaster risk reduction planning in coastal urban regions. Following a literature review, which identifies the interconnections between sand resources and coastal pressures, this study presents a conceptual framework of the Sand Resources – Disaster Risk Reduction – Coastal Urbanisation (SR/DRR/CU) nexus. These nexus elements are then connected using a causal loop diagram (CLD) to analyse the system dynamics. This reveals that maintaining natural sediment transport processes, integrating sediment resource management across the nexus elements, improving data on private development, and limiting development in low elevation coastal zones (LECZs) are key leverage points to prevent exponential collapse of the nexus. Finally, this study conducts a case study which maps sediment resource management in the Mississippi River Delta Basin (MRDB). Strong regional institutions in the MRDB, notably the Louisiana Sediment Management Plan (LASMP), are examples of how urbanised deltas can improve regional sediment management while enhancing coastal resilience. The case study also exposes that sand resource management is not integrated across urban development projects and coastal restoration projects. This study suggests that using the SR/DRR/CU nexus as a resource governance model can improve regional disaster risk reduction strategies provided it is data-backed, adapted to local context, and includes public and private development projects.