The need for innovations for etreme climatic events (INXCES), the progress of flood modeling case Bergen Norway

Urban flooding has become a key issue for many cities around the world. With the continuing effects of climate change, this will become more acute and will add to the serious problems already experienced in dense urban areas. Therefore several international stakeholders are in the need of tools that can assess the vulnerability to floods and visualization tools that will contribute to international knowledge exchange. Years ago scientists started to use DEMs (digital elevation maps) as quick scans to indicate locations that are vulnerable to urban flooding and the effect of climate change. Now the datasets are getting bigger and stakeholders are becoming more demanding and require faster and more visual results. The technology using DEMs is becoming more common and improved, both with a higher accuracy and a higher resolution. As an example the flood modeling using DEMs is compared for the case Bergen in Norway (figure 1a and 1b) from 2009 and 2016

Floodfighting in Almere:onderzoeksresultaten hydraulisch functioneren wadi’s en doorlatende verharding

Veel waterschappen en gemeenten vragen zich af of de regenwatervoorzieningen die de laatste decennia op veel plaatsen zijn aangelegd, op lange termijn goed functioneren en of de implementatie kosteneffectief is. Onderzoek in Almere leert dat de infiltratiecapaciteiten van wadi’s voldoende zijn om het water binnen enkele uren te verwerken. Bij doorlatende verharding wordt vaak dichtslibbing aangetoond, maar ook na enkele jaren kunnen de infiltratiecapaciteiten nog boven de ingrijpmaatstaf liggen. Bij goed ontwerp, aanleg en beheer kunnen deze regenwatervoorzieningen een goede bijdrage leveren aan het vasthouden, bergen en afvoeren van regenwater in het stedelijk gebied

Flood model Bergen Norway and the need for (sub-)surface innovations for eXtreme Climatic EventS (INXCES)

Urban flooding has become a key issue for many cities around the world. The project 'INnovations for eXtreme Climatic EventS' (INXCES) developed new innovative technological methods for risk assessment and mitigation of extreme hydroclimatic events and optimization of urban water-dependent ecosystem services at the catchment level. DEMs (digital elevation maps) have been used for more than a decade now as quick scan models to indicate locations that are vulnerable to urban flooding. In the last years the datasets are getting bigger and multidisciplinary stakeholders are becoming more demanding and require faster and more visual results. In this paper, the development and practical use of DEMs is exemplified by the case study of Bergen (Norway), where flood modelling using DEM is carried out in 2017 and in 2009. We can observe that the technology behind tools using DEMs is becoming more common and improved, both with a higher accuracy and a higher resolution. Visualization tools are developed to raise awareness and understanding among different stakeholders in Bergen and around the world. We can conclude that the evolution of DEMS is successful in handling bigger datasets and better (3D) visualization of results with a higher accuracy and a higher resolution. With flood maps the flow patterns of stormwater are analysed and locations are selected to implement (sub-)surface measures as SuDS (Sustainable Urban Drainage systems) that store and infiltrate stormwater. In the casestudy Bergen the following (sub-)surface SuDS have been recently implemented with the insights of DEMS: settlement storage tank, rainwater garden, swales, permeable pavement and I/T-drainage. The research results from the case study Bergen will be shared by tools to stimulate international knowledge exchange. New improved DEMs and connected (visualization) tools will continue to play an important role in (sub-)surface flood management and climate resilient urban planning strategies around the world

Understanding urban hydrology through measurements of infiltration capacity of permeable pavements under real-live circumstances

Over the past decades various types of permeable pavements have been implemented in different municipalities in the Netherlands in order to improve infiltration capacity in urban areas and therewith being able to better treat stormwater runoff. With initial promising results this adaptation measure seemed to be the solution for urban flooding due to extreme precipitation. However, in practice, foreseen infiltration capacities were usually not met, often due unknown reasons. To better understand the functioning of permeable pavements in practice, we have studied - as part of the project Infiltrating Cities - over 100 existing permeable pavement installations in the Netherlands. At each location, infiltration capacity was tested through a full-scale infiltration testing procedure (flooded area about 40 m2) while conditional on-site factors were collected (location, age, type of permeable pavement, street-type, traffic density, vicinity of urban green, regular maintenance regime, etc.). By coupling this information we analyzed how these factors influence the infiltration capacity of permeable pavements in practice, e.g. through accelerated deterioration of infiltration capacity through time. In addition, we evaluated for a selected number of installations, how various types of maintenance may counteract this deterioration, hence improving the infiltration capacity of permeable pavements

From Pilot Projects to Transformative Infrastructures, Exploring Market Receptivity for Permeable Pavement in The Netherlands

Climate change and changing land use challenge the livability and flood safety of Dutch cities. One option cities have to become more climate-proof is to increase infiltration of stormwater into soil through permeable pavement and thus reduce discharge of stormwater into sewer systems. To analyze the market receptivity for permeable pavements in the Netherlands, this article focuses on the perception of end-users towards key transition factors in the infrastructure transformation processes. Market receptivity was studied on two levels: (1) on the system level, by analyzing 20 key factors in the Dutch urban water sector that enable wider application of permeable pavements; and (2) on the technology level, by analyzing 12 key factors that explain why decision makers select permeable pavements or not. Results show that trust between cooperating partners was perceived as the system level key factor that needs to be improved most to facilitate the wider uptake of permeable pavements. Additionally, the association of end-users with permeable pavement, particularly their willingness to apply these technologies and their understanding of what kinds of benefits these technologies could bring, was regarded the most important receptivity attribute. On the technology level, the reliability of permeable pavement was regarded as the most important end-user consideration for selecting this technolog

Are urban water bodies really cooling?

Small urban water bodies, like ponds or canals, are often assumed to cool their surroundings during hot periods, when water bodies remain cooler than air during daytime. However, during the night they may be warmer. Sufficient fetch is required for thermal effects to reach a height of 1–2 m, relevant for humans. In the ‘Really cooling water bodies in cities’ (REALCOOL) project thermal effects of typical Dutch urban water bodies were explored, using ENVI-met 4.1.3. This model version enables users to specify intensity of turbulent mixing and light absorption of the water, offering improved water temperature simulations. Local thermal effects near individual water bodies were assessed as differences in air temperature and Physiological Equivalent Temperature (PET). The simulations suggest that local thermal effects of small water bodies can be considered negligible in design practice. Afternoon air temperatures in surrounding spaces were reduced by typically 0.2 °C and the maximum cooling effect was 0.6 °C. Typical PET reduction was 0.6 °C, with a maximum of 1.9 °C. Night-time warming effects are even smaller. However, the immediate surroundings of small water bodies can become cooler by means of shading from trees, fountains or water mists, and natural ventilation. Such interventions induce favorable changes in daytime PET.</p

High resolution thermal stress mapping in africa:decision maps for urban planning in Johannesburg

Urban planning will benefit from tools that can assess the vulnerability to thermal stress in urban dense cities. Detailed quick-scan heat stress maps, as made in this study for Johannesburg, have proven valuable in the decision-making process on this topic. It raised awareness on the urgent need to implement measures to tackle the effects of climate change and urbanization. Awareness on heat stress has led to the implementation of measures to mitigate the effects of climate change. As in other countries, nature-based solutions (e.g. green roofs and walls, swales, rain gardens, planting trees etc) are considered in urban areas in South Africa for various reasons. The awareness of the effect of nature based solutions on heat stress is still low, which can be improved by the use of heat stress maps. Some of these measures are already mapped on the open source web tool, Climate-scan (www.climatescan.nl) for international knowledge exchange around the globe