Water and land management scenarios for addressing land subsidence in the Netherlands

Land subsidence is a wicked problem that presents significant challenges to both urban and rural areas in the Netherlands. With annual subsidence rates reaching up to 10 mm in urban areas and over 30 mm in rural polder areas, the increasing damage caused by subsidence represents a long-term economic burden at both regional and national levels. Additionally, the land subsidence process contributes to greenhouse gas (GHG) emissions, further exacerbating environmental challenges. Addressing the persistent losses and emissions associated with land subsidence is a complex task that requires a holistic approach.

This study explores the role of integrated water and land management in mitigating land subsidence and the associated impacts on both society and the Earth system, using our backcasting approach developed within the Living on Soft Soils research programme [nwa-loss.nl]. This approach begins by formulating alternate long-term objectives for 2050, focusing on minimizing subsidence rates, reducing subsidence-related GHG emissions, and mitigating associated economic damage. These objectives were explicitly defined for both rural and urban contexts, with input from scientists and stakeholders. The three alternate objectives reflect varying levels of ambition and feasibility, with continued unaltered management practises, representing the business-as-usual scenario, serving as a baseline for comparison. Next, preparing the backcasting approach requires to define and select the water and land management measure sets that simulation modelling may select to alter land subsidence and the associated impacts from business as usual. Between rural and urban areas, the water management strategies of reducing the groundwater level lowering are fairly similar, but for the land management strategies there are strong context differences. In some rural areas, to reach the long-term objective one may opt for drastic land use changes, e.g. changing established agriculture into paludiculture, or reallocating land to forests or wetlands (in tandem with raising groundwater tables, serving GHG reduction and ecosystem restoration goals), while maintaining established agricultural use in other rural areas with higher groundwater levels and less drastic water management measures or less reducing the groundwater level lowering. In urban areas, land management strategies focus on soil stabilization, blue-green infrastructure, and district-level interventions to mitigate subsidence while enhancing urban resilience to climate change.

The modelling steps in this study explore the solution space and develops land subsidence management scenarios towards the three sustainable long-term objectives. Model runs using the water and land management strategies either individually or in different combinations. The performance of scenarios is evaluated based on their ability to reduce subsidence and the associated socioeconomic cost terms. With the performance analysed, the outcomes are lined up to introduce sustainable pathways for implementing measure sets, allowing stakeholders and decision-makers to make informed decisions and choose the most feasible and sustainable options, ensuring that these interventions are tailored to the local context and conditions, and also that these interventions contribute to broader Earth system sustainability.

In conclusion, this study highlights the role of integrating water and land management strategies in addressing land subsidence via a framework provides scenarios and pathways toward achieving sustainable land subsidence management in the Netherlands.