Nature-based solutions (NBS) bieden veel kansen om de waterveiligheid te verhogen en tegelijkertijd natuurwaarden te versterken. In dit artikel worden zowel een aantal ecologische en juridische aspecten besproken als de consequenties van NBS in voorlanden tussen dijk en water, ten behoeve van het overstromingsrisicobeheer.
MULTIFILE
As a consequence of climate change and urbanization, many cities will have to deal with more flooding and extreme heat stress. This paper presents a framework to maximize the effectiveness of Nature-Based Solutions (NBS) for flood risk reduction and thermal comfort enhancement. The framework involves an assessment of hazards with the use of models and field measurements. It also detects suitable implementation sites for NBS and quantifies their effectiveness for thermal comfort enhancement and flood risk reduction. The framework was applied in a densely urbanized study area, for which different small-scale urban NBS and their potential locations for implementation were assessed. The overall results show that the most effective performance in terms of flood mitigation and thermal comfort enhancement is likely achieved by applying a range of different measures at different locations. Therefore, the work presented here shows the potential of the framework to achieve an effective combination of measures and their locations, which was demonstrated on the case of the Sukhumvit area in Bangkok (Thailand). This can be particularly suitable for assessing and planning flood mitigation measures in combination with heat stress reduction.
As the field of climate adaptation has entered an implementation and acceleration phase, measures for urban water and heat management are rapidly spreading in cities across the globe. Especially nature-based solutions have seen a recent rise in implementation to fight flooding, heat, drought, and biodiversity loss. Despite decades of experience, there is still a lot unknown about the long-term functioning of these measures and how this relates to design, development, and maintenance decisions. To this end, this chapter explores the relations between characteristics and performances of urban nature-based solutions, based on empirical research conducted in over 50 swales throughout the Netherlands between 2021 and 2022. The research combined various fieldwork methods such as full-scale infiltration tests to assess the hydraulic functionality and heavy metal accumulation tests by using an XRF-scanner, as well as neighborhood surveys to assess local perceptions of these swales and their functions. This chapter describes and illustrates these approaches for mapping and assessing the performance of swales, followed by a reflection on their suitability for linking design choices and performance indicators. Based on national guidelines, these indicators help to establish minimal performance quotas to evaluate and compare the performance of swales. While most of the researched swales met national criteria for hydraulic performance, almost a third of investigated swales exceeded norms for heavy metal accumulation. By building up a national database of swales and data derived through measurements, we attempt to find patterns among successes and failures in swale design through cross-case comparison, but conclude that these heavily rely on local circumstances and context-depending design choices. Expanding on mapping, assessment, and evaluation approaches can lead to a better understanding of these context-depending chances and risks for developing nature-based solutions.
Restoring rivers with an integrated approach that combines water safety, nature development and gravel mining remains a challenge. Also for the Grensmaas, the most southern trajectory of the Dutch main river Maas, that crosses the border with Belgium in the south of Limburg. The first plans (“Plan Ooievaar”) were already developed in the 1980s and were highly innovative and controversial, as they were based on the idea of using nature-based solutions combined with social-economic development. Severe floodings in 1993 and 1995 came as a shock and accelerated the process to implement the associated measures. To address the multifunctionality of the river, the Grensmaas consortium was set up by public and private parties (the largest public-private partnership ever formed in the Netherlands) to have an effective, scalable and socially accepted project. However, despite the shared long term vision and the further development of plans during the process it was hard to satisfy all the goals in the long run. While stakeholders agreed on the long-term goal, the path towards that goal remains disputed and depends on the perceived status quo and urgency of the problem. Moreover, internal and external pressures and disturbances like climate change or the economic crisis influenced perception and economic conditions of stakeholders differently. In this research we will identify relevant system-processes connected to the implementation of nature-based solutions through the lens of social-ecological resilience. This knowledge will be used to co-create management plans that effectively improve the long-term resilience of the Dutch main water systems.
The Dutch main water systems face pressing environmental, economic and societal challenges due to climatic changes and increased human pressure. There is a growing awareness that nature-based solutions (NBS) provide cost-effective solutions that simultaneously provide environmental, social and economic benefits and help building resilience. In spite of being carefully designed and tested, many projects tend to fail along the way or never get implemented in the first place, wasting resources and undermining trust and confidence of practitioners in NBS. Why do so many projects lose momentum even after a proof of concept is delivered? Usually, failure can be attributed to a combination of eroding political will, societal opposition and economic uncertainties. While ecological and geological processes are often well understood, there is almost no understanding around societal and economic processes related to NBS. Therefore, there is an urgent need to carefully evaluate the societal, economic, and ecological impacts and to identify design principles fostering societal support and economic viability of NBS. We address these critical knowledge gaps in this research proposal, using the largest river restoration project of the Netherlands, the Border Meuse (Grensmaas), as a Living Lab. With a transdisciplinary consortium, stakeholders have a key role a recipient and provider of information, where the broader public is involved through citizen science. Our research is scientifically innovative by using mixed methods, combining novel qualitative methods (e.g. continuous participatory narrative inquiry) and quantitative methods (e.g. economic choice experiments to elicit tradeoffs and risk preferences, agent-based modeling). The ultimate aim is to create an integral learning environment (workbench) as a decision support tool for NBS. The workbench gathers data, prepares and verifies data sets, to help stakeholders (companies, government agencies, NGOs) to quantify impacts and visualize tradeoffs of decisions regarding NBS.
‘Bomentaal’ betreft de ruimtelijke samenhang tussen boomsoorten, beplantingstypen en boomstructuren, en hun specifieke locatie (stad, wijk of straat). Dit onderzoek naar de configuraties van boombeplanting in Delft is de eerste stap om een nieuwe methodiek te ontwikkelen om dit vocabulaire van boomstructuren in Nederlandse laaglandsteden te ontrafelen, als drager en handvat voor de herziening en uitbreiding van het urban forest in Nederland. Stadsbomen zijn de ruggengraat van de groene stedelijke ruimte en leveren een belangrijke bijdrage aan het omgaan met gevolgen van klimaatverandering zoals hittestress, wateroverlast, luchtkwaliteit en achteruitgang van biodiversiteit. Dit is niet los te zien van de baten voor de gezondheid, de leefbaarheid, en het versterken van de stedelijke identiteit. Dit vraagt om een evaluatie en uitbreiding van het urban forest. Omdat de uitbreiding van het urban forest plaats zal vinden in en om bestaande steden is kennis van de bomentaal van deze steden onontbeerlijk. Het onderzoeken van de bestaande bomentaal - het scheppen van een ordening en het benoemen en tonen van essentiële eigenschappen verschillende typen boomstructuren - is onontbeerlijk bij de herziening en uitbreiding ervan. Voor dit onderzoek is gekozen voor de stad Delft: een typische laaglandstad met een lange geschiedenis van stedelijke boombeplanting, en een grote transformatieopgave wat betreft uitbreiding en vernieuwing van de woningvoorraad, klimaatadaptatie, gezondheid en welzijn, leefbaarheid en het behoud van identiteit. Door de kleine schaal van Delft kan de ontsluiting van diens bomentaal derhalve als test-case dienen voor het ontwikkelen van methodes, inzichten en perspectieven voor het urban forest van het Nederlandse laagland. Het onderzoek analyseert de kenmerkende beplantingsstructuren in Delft op drie schaalniveaus (boom, boomarrangementen, groenstructuur) in diagrammatische tekeningen, beelden en tekst op basis van veldonderzoek, historische documentatie en cartografisch onderzoek. Zowel de fysiek-ruimtelijke, technische als sensorische aspecten van de bomentaal worden in kaart gebracht.
