Many nature-based solutions are seen as favourable and effective measures to increase urban resilience during more extreme weather events, by for example decrease high temperatures in summer. Since space is often scarce in urban environments, roofs have received increased attention in mitigating the consequences of climate change in urban areas. This resulted in a variety of roof systems of green and blue-green roofs designed as an integral part of the built environment due to their hydrological, insulative and biodiverse capacities. This study examined the impact of blue-green, and conventional roofs on roof surface temperatures, indoor temperatures and insulative properties of the building. Temperature sensors (IButtons) have been used for summer and winter measurements on roofs for early 20th century buildings in the city of Amsterdam (NL).The results indicate the strongest effect of blue-green roofs on surface temperatures in summer, with significantly lower surface temperatures (2-3°C) than for conventional roofs. During winter days, the surface temperatures were not significantly different on blue-green roofs than on conventional roofs. The measurements in the water crate layers of blue-green roofs show an all year-round temperature buffering effect. During hot summer days, the temperature in the water storage of the blue-green roof was much lower than other measured surfaces (up to 12 °C and 7 °C compared to gravel roofs and the blue-green roof substrate, respectively) and also experienced the least diurnal variation. Similarly, the empty water crate layer showed up to 3 °C higher minimum temperatures during cold winter nights. The measurements also show a small positive systematic effect on the indoor environment under a blue-green roof compared to traditional gravel roof type. The variation in indoor temperature is smaller underneath the blue-green roofs compared to the reference roofs during both warm and cold periods (0.19 – 0.35 °C reduction in STD). This suggests that rooms located under a blue-green roof are less sensitive to the outside air temperature and its natural diurnal variation.Although the effect on indoor thermal comfort seems to be small, blue-green roofs contribute to overall greening of the city. Second, thanks to the water storage the potential for growing biodiverse vegetation is higher than on extensive green roofs.
Green roofs received increased scientific attention with respect to climate adaptation in urban environments for their hydrological, biodiversity and insulative capacities. Yet, the thermal properties of roofs with an additional water layer underneath the vegetation substrate (blue-green roofs) are not well represented in scientific research. In this field study, we examined the impact of surface temperatures, indoor temperature and insulative properties of blue-green, green, and conventional gravel/bitumen roofs in the city of Amsterdam for early 20th century buildings. Temperature sensor (IButtons) results indicate that outside surface temperatures of blue-green roofs were more stable than for conventional roofs. For instance, for three warm periods during summer (2021) surface substrate temperatures peaked much higher for gravel roofs (+8 oC) or bitumen roofs (+18 oC) than for blue-green roofs. On top of that, during a cold period in winter average water crate layer temperatures remained 3.0 oC higher and much more stable than substrate temperatures of blue-green roofs and conventional roofs, implicating that the blue layer functions as an extra temperature buffer. The effect of lower daily variation of surface temperatures in winter and summer is also reflected by inside air temperatures. Inside temperatures showed that locations with blue-green roofs are less sensitive to outside air temperatures, as daily temperature fluctuations (standard deviations) were 0.19 and 0.23 oC lower for warm and cold periods, respectively, compared to conventional roofs. This effect seems rather small but comprises a relatively large proportion of the total daily variation of 24% and 64% of warm and cold periods respectively.
Mexican oregano is a non-timber forest product harvested in natural vegetation and represents an important source of income for rural families. Recent reports have highlighted decreases in natural populations caused by increased harvest intensity. Oregano leaf harvesting is a complex problem, involving different components and views, and has a clear spatial dimension. We proposed an analytical framework based on multi-criteria-multi-objective analyses. GIS tools were used as the platform for managing, displaying and analyzing ecological and socioeconomic information from different sources in order to evaluate land suitability of three different management strategies for two competing land objectives: oregano Harvest and oregano Regeneration. The incorporation of environmental evaluation criteria in the analysis allowed the identification of new potential oregano harvesting areas which were neither reported by harvesters, nor registered during harvesting trips. Socio-economic criteria, such as land tenure, highlighted the fact that a substantial proportion of current oregano harvesting areas are located outside ejido limits resulting in potential conflicts for resource access. The proposed Balanced oregano management strategy, in which the same proportion of suitable area (50%) was assigned to both objectives, represents the most favorable management strategy. This option allows harvesters to continue earning an income from oregano leaf harvest; and at the same time helps in the selection of the best areas for oregano regeneration. It also represents a management strategy with a smaller impact on oregano populations and on the harvesters ́ income, as well as lower monitoring costs. The proposed analytical frame-work may contribute to advance the application of systematic approaches for solving decision-making problems in areas where oregano leaves and other NTFP are harvested.
MULTIFILE
Zand en andere grove grondstoffen worden steeds schaarser door intensief gebruik in infrastructuur en industrie, terwijl miljarden kubieke meters slib wereldwijd worden uitgebaggerd om vaargeulen en havens operationeel te houden. Vanwege dit groeiende tekort aan traditionele grondstoffen is er behoefte aan het ontwikkelen van nieuwe methodieken voor hergebruik van slib en lokaal sediment, onder andere voor dijkversterking en ophoging van landbouwgronden. Echter wordt gebaggerd slib volgens de regelgeving nog als een van de grootste potentiële afvalstromen gezien. Ook is slib complexer in het gebruik omdat het bestaat uit een heterogeen mengsel van onder meer water, zand, organisch materiaal, fijnstof en gas. Vanwege schaarste in bouwmaterialen lopen er steeds meer initiatieven voor het nuttig hergebruiken van gebaggerd slib, maar de optimale laagdikte en aanlegtechnieken moeten nog worden onderzocht. Met dit project zoeken lectoraat Sustainable River Management samen met Hogeschool Van Hall Larenstein en de praktijkpartners Klaei B.V., Waterschap Noorderzijlvest en EcoShape naar de best practices voor het produceren van waardevol klei uit havenslib. Via laboratoriumexperimenten en veldproeven binnen grootschalige pilots worden mechanische eigenschappen van havenslib uit de Lauwersoog haven in beeld gebracht. Er wordt gezocht naar de optimale dikte van havenslib om bruikbare klei te produceren. Daarbij wordt onderzocht of de mechanische eigenschappen van de geproduceerde klei afhankelijk zijn van de laagdikte van de initiële laag of havenslib. De resultaten verbinden de laagdikte in rijpingscompartimenten met materiaaleigenschappen en monitoren de initiële verouderingsprocessen na de aanleg van de klei in een proefdijk. Het eindresultaat biedt inzicht in de best practices voor toepassing van havenslib en de daarbij horende materiaaleigenschappen. Dit project draagt daarmee direct bij aan de ontwikkeling van een nieuw, duurzaam materiaal voor gebruik in dijkversterkingen en landbouw en een circulaire economie in Nederland in 2050.
In the coming four years, the Hedwige-Prosperpolder in the Schelde estuary will be reopened for nature restoration. This creates opportunities, within a binational Dutch-Belgian consortium, to experiment with the existing dike and to perform targeted dike breach experiments and breach monitoring. We will exploit this opportunity to investigate a newly described, potentially valuable contribution of vegetated foreshores to flood safety: the restriction of dike breach extent, and thus of flooding volume, in the case of failure of the dike. Fostering marsh development in front of realigned dikes could improve safety more than hitherto thought. Not only does it reduce dike failure probabilities, it may also restrict the consequences of failures. Even though this is not the primary goal of the HPP realignment, in this Living Lab we will study how management realignment can be used as a nature-based solution for flood safety. We will model the contribution of vegetated foreshores to breach development, calculate its contribution to reduction of risks, and validate the model using the breach experiment. We will also study the conditions for, and rates of, vegetation and soil strength development in front of realigned dikes. We will explore novel designs and maintenance schemes for realigned dikes connected to a vegetated foreshore. Finally, we will study how people experience physical changes in the landscape in terms of place attachment: will they be reconnected to the changed landscape when properly informed on the new role of this landscape in ecosystem development and safety enhancement? The project consortium is composed of engineers, ecologists and social scientists with a strong track record in multidisciplinary co-operation. It is externally supported by national and regional water authorities, contractors and engineering companies. It is ideally situated to translate new knowledge into operational procedures, and incorporate this into the education of future coastal professionals.
In recent years there has been an increasing need for nature inclusive solutions in the construction sector. The practice asks for new solutions contributing to the development of sustainable, resilient and liveable cities. Under the guidance of the Dutch government, greening of the cities has become one of the aims of municipalities in the Netherlands and the focus of some emerging companies and design offices. In cities, quay masonry walls, thanks to their close contact with water, have the potential to be ecologically engineered to favour vegetation, thereby contributing to the renaturing of urban areas. By building a prototype of an innovative masonry building system, this project aims to investigate the potential for improving the integration between masonry quay walls and vegetation. The set-up consists of a dry-stacking system for brick masonry: strong polyamide elements interconnect the bricks, providing strength to the masonry without the need for mortar. The space in between bricks, traditionally filled with mortar, is to be filled with compost material, providing an ideal substrate for plant growth and a buffer for water storage (figure 1). In addition to improved integration between masonry walls and vegetation, the proposed dry-stacking system allows for easy reuse of bricks, thereby contributing to circularity and sustainability of the building industry. The project broadens and strengthens the national network in the field of urban ecology by bringing together expertise from the fields of architecture, ecology and the construction sector, from both academia and practice.
