Coastal erosion threatens flood safety and other uses of beaches and dunes globally. In the Netherlands a coastline maintenance policy was implemented in the 1990's to address the negative effects of erosion, with sand nourishments as the primary means. In this study, the cumulative effects of these nourishments are evaluated against the strategic goal of sustainable preservation of the uses and values of the coast. This research aims to inform national and international policy makers, practitioners, and scientist about the possible long-term effects of coastal management with structural sand nourishments. Coastal indicators were analysed to quantify the morphological evolution of the coast before and since coastline maintenance. It is observed that regular nourishments serve to halt structural coastline retreat. The coastline built out, on average, which was necessary to achieve maintenance of the most erosive areas. Additionally, strong dune growth is observed since the start of coastline maintenance, thanks to wind-driven transport of nourished sand and more dynamic dune management. Nourishments thus contribute positively to flood safety, although flood safety is not an automatic benefit of coastline maintenance. Space for recreation and nature is maintained or improved: the dry beach width was unaffected, and dune areas have grown. Further, it is reported that the impact of nourishments on the coastal ecosystem is local and temporary, leading to the inference that uses and values of the coast are being maintained sustainably through regular nourishments. Overall, the approach of coastline maintenance with regular pro-active nourishments has thus proven to be successful.

Living labs have emerged as a long-term, collaborative approach to addressing complex societal challenges, such as sustainable land and water management and climate change adaption. While these transdisciplinary environments foster continuous knowledge exchange and interactions among actors from diverse disciplines and sectors, the role of learning in realizing the impacts of living labs on participating actors and broader society is often underexplored. This paper aims to identify and analyze learning that occurs within a sequence of co-creative activities and their resulting outcomes, using the concept of ‘learning pathways’. The ‘living lab learning framework’ provides a systematic approach to organizing and categorizing living lab activities, enabling to infer learning pathways. An ex-post analysis of an empirical case study on a climate adaptation project, KLIMAP, resulted in seven distinct learning pathways: 1) harnessing collective integrated knowledge, 2) building collaborative networks, 3) enhancing stakeholder capacity, 4) adapting and contextualizing knowledge, 5) diffusing knowledge, 6) facilitating co-creation, and 7) reflecting on learning. These pathways were developed by examining the types of learning activities, their processes, and the entities involved, linking them to the outcomes achieved. The findings highlight that learning pathways contribute to identifying outcomes and broader impacts of living labs.

In this paper, we closely examine the case of the Marker Wadden, a nature restoration project with recreational opportunities in the Dutch lake Markermeer. The Marker Wadden – a mud island concept – has been constructed using locally sourced building materials (sediments from the lake) and is designed to withstand natural dynamics such as storms and waves. Lack of funding and financing has been repeatedly discussed and identified as a key barrier to implementing and upscaling ecological restoration, or Nature-based Solutions (NbS) in general. This highlights the importance of studying a unique case, such as the Marker Wadden, where this well-documented barrier has been overcome. We aim to identify the financial arrangements made and how they came about. We adopt the rounds model (a policy analysis theory), apply evidence triangulation, and employ a theoretical framework that captures an institutional perspective on financial barriers. We find the Marker Wadden project to be an example of public and private co-funding for ecosystem restoration. We further find revenue generation from recreational activities leads to partial cost-recovery, and non-public funding sources are unlocked due to the involvement of an NGO. We also find the pre-investment phase to be instrumental in overcoming financial barriers during later (implementation) phases. We surface the main drivers that led to funding for the Marker Wadden project, reveal opportunities for investment planning for NbS, and expose trade-offs in terms of (democratic) equity, efficiency, and environmental outcomes resulting from the combined public, private, and philanthropic co-funding arrangements used.

Complex issues like sustainable land and water management demand a transdisciplinary and collaborative approach, such as that of living labs, bridging between science, policy, and society. Living labs facilitate active collaboration among diverse actors from public and private sectors, research institutes, and civil society, creating an environment that fosters innovations to address environmental challenges. However, the impact of these labs is often assessed based only on their immediate results, overlooking the potential effects of learning during co-creation activities. Thus, this paper develops a framework that allows to capture learning in a living lab co-creative environment. In response to widespread calls for an epistemological basis for living labs, the study bases the framework on relevant learning theories. First, the literature dealing with learning theories relevant to the characteristics of living labs is reviewed. The relevant theories are identified as: behaviorism, cognitivism, constructivism, experimental, situated, social, organizational, transformative, and connectivism. Next, the insights on learning theories are used in developing a Living Lab Learning Framework with three interacting components: A. Learning types (what), B. Learning process (how), and C. Learning levels (who), contributing to learning outcomes. The framework distinguishes content, capacity, and network as learning types; intentional or incidental as learning processes; and individual, team, and organization as learning levels. Finally, the potential application of the framework during the initiation, implementation, and evaluation project phases of living labs is highlighted. The framework is envisaged to extend the impacts of living labs beyond immediate results by providing a systematic method for assessing learning and its outcomes and generating insights regarding future improvements in the configuration of living lab learning environments.

Managing natural resources in transboundary river basins is a complex task in which societal needs and environmental impact are intertwined. The nexus paradigm engages with such a challenge by analysing synergies and trade-offs across Water-Energy-Food-Ecosystems (WEFE) sectors. We present a WEFE nexus operationalisation using a participatory modelling approach in the transboundary Lielupe river basin, shared between Latvia and Lithuania. Using a modelling cycle approach, we illustrate a stakeholder-driven pathway from generic and qualitative to increasingly quantitative system tools useful for basin-scale policy analysis. Stakeholders prioritised agricultural nutrient pollution as a critical nexus issue strongly linked to land-use. Three policy alternatives to address this issue were co-identified with stakeholders from both riparian countries: (i) implementing nature-based solutions; (ii) transitioning to organic agriculture; and (iii) promoting arable land-use transitions to former native landscapes. The long-term effect of such policies is explored using a System Dynamics simulation model. Results highlight the importance of promoting active transboundary cooperation for water quality control, as unilateral action hampers the effect of long-term ambitious policies. Even highly ambitious unilateral action can delay the achievement of river basin quality objectives in the order of a decade, a critical finding for the wider Baltic region and the achievement of EU water quality objectives. Based on an exploratory analysis, we found that implementing basin-scale solutions for nutrient control would reduce nitrogen concentration by around 30 % with a 2 % co-benefit of increasing vegetation stocks, yet at the cost of decreasing cereal production by 8 %. This work illustrates the capabilities of a tailor-made simulation model crafted to answer locally relevant policy questions with a nexus perspective in a transboundary river basin. Developing and using a simulation model in a participatory way can explore policy futures while fostering dialogue among riparian stakeholders. This is a promising way to promote cooperation towards solving critical socio-environmental issues in transboundary rivers.

Water renewal and flushing in small, intermittently open or closed estuaries is receiving increasing attention particularly in light of the climate change induced alterations in run-off, wave and sediment transport conditions along coasts. The challenges of predicting the stratification-circulation state and the balance between tidal or freshwater flushing in response to the mouth dynamics of small, wave-dominated estuaries is the focus of the paper. Such predictions are required for determining estuary freshwater requirements or establishing an estuary's capacity to maintain sound water quality under pollutant discharges. Advances in simulating changes in stratification-circulation over long time scales are limited. Instead attention has focused on generating indices of stratification or water quality state using heuristic methods. In this paper, systems dynamics modelling is applied to simulate the non-linear response of the estuary to changes in river and marine water fluxes. The estuary is modelled as a basin with a specified water volume to water level relationship, connected to the sea by a channel with variable sill height, but fixed width. The direction and magnitude of the flow through the mouth determines whether the sill height erodes or accretes and hence the mouth dynamics (see Slinger, 2017). The tidal flux through the mouth co-determines the volumetric exchange of salt, influencing both the stratification state of the estuary and the degree of tidal or freshwater flushing. This is also influenced by run-off. The resulting dynamic balance is captured in two bulk indices, the Estuarine Richardson number and the bulk densimetric Froude number. Using measured data from the Great Brak Estuary, South Africa, the model is calibrated. Model simulations demonstrate the importance of tidal flushing and concomitant mouth breaching for water renewal as freshwater flushing declines under scenarios of increased water abstraction. Although the estuary remains partially mixed, there is increased average salinity and a more uniform the water column. Water releases and mouth breaching bring about a more natural stratification-circulation state, but these effects are short-lived.

Problems manifested within social-ecological systems (SES) exhibit dynamic complexity and hold implications for current and future human well-being and environmental sustainability. The complexity of these issues, the ever-present uncertainty inherent to SES, and the multi-stakeholder settings in which they are discussed call for participatory modelling to support decision-making on socio-environmental issues. Yet, this challenging endeavour requires a structured approach — a modelling cycle — to facilitate engagement with the implications of participation and uncertainty as focal points for Good Modelling Practice (GMP). Here we propose an integrated policy analysis framework for SES modelling using System Dynamics (SD). This framework stems from integrating two existing modelling cycles that individually consider participation and uncertainty in SD modelling. Three global modelling phases and a set of tools to address the participation and uncertainty features in SES modelling are distinguished. The framework contributes to mainstreaming GMP, offering a structured model-based approach to enhance the robustness and social acceptance of policies on critical socio-environmental issues.