A decision support framework for subsidence risk reduction in urban areas

Weather extremes and climate change can exacerbate subsidence in urban costal and delta areas. Subsidence risk management requires strategies that integrate mitigation and prevention of both ground sinking and damage to constructions. These strategies include structural (i.e., technical) measures, such as soil improvements, groundwater management and construction enhancements, and non-structural (i.e., non-technical) measures, such as policies, regulations, and urban planning. Despite their importance, local governments often lack systematic methodologies for choosing appropriate measures.

This study presents a practical framework to assist stakeholders and policymakers in managing subsidence and damage to constructions in urban areas. The framework evaluates the applicability and effectiveness of structural mitigation and prevention measures to identify optimal solutions.

The first step involves determining the applicability of measures using a Question-and-Response (Q&R) system. The system features eight inquiries that address critical factors influencing the decision-making: the primary cause of subsidence, the dominant geology of the area, the objective of the intervention, the scale of application, and the type of urban area. Based on the responses to these questions, the framework generates a list of applicable measures aligned with local priorities. Then,  the selected measures are further evaluated for their effectiveness using four qualitative indicators: reduction potential, operational reliability, negative impact and service life. The reduction potential indicates how much subsidence or damage to construction is reduced; the operational reliability determines the functionality of a measure during its life; the negative impact accounts for any potential adverse effect; and the service life reflects the expected durability of a measure.

By combining applicability and effectiveness assessments, stakeholders and policy makers can refine their selection of structural measures in urban areas ensuring that they are both practical and impactful. The proposed procedure is based on a review of 52 scientific publications, and insights from surveys and expert sessions. This ensures that the methodology reflects current best practices and knowledge in subsidence risk management.

While the framework offers a valuable tool for conducting a quick scan of suitable solutions, it requires further refinement to enhance its utility. Future improvements will include cost-benefit analyses, thus enabling more comprehensive evaluations of the performance of structural measures for subsidence mitigation and prevention. Additional enhancements may involve sustainability assessment and social safety to balance the financial feasibility with environmental and social impacts.

The proposed framework represents a promising step forward in subsidence risk management. By systematically addressing the applicability and effectiveness of mitigation and prevention measures, it equips local governments with a structured approach to tackle subsidence challenges in urban settings.