Greater New Orleans is surrounded by wetlands, the Mississippi River and two lakes. Excess rain can only be drained off with pumping systems or by evaporation due to the bowl-like shape of a large part of the city. As part of the solution to make New Orleans climate adaptive, green infrastructure has been implemented that enable rainfall infiltration and evapotranspiration of stored water after Hurricane Katrina in 2005. The long-term efficiency of infiltrating water under sea level with low permeable soils and high groundwater tables is often questioned. Therefore, research was conducted with the full-scale testing method measuring the infiltration capacity of 15 raingardens and 6 permeable pavements installed in the period 2011–2022. The results show a high variation of empty times for raingardens and swales: 0.7 to 54 m/d. The infiltration capacity decreased after saturation (ca 30% decrease in empty time after refilling storage volume) but all the tested green infrastructure met the guideline to be drained within 48 h. This is in contrast with the permeable pavement: only two of the six tested locations had an infiltration capacity higher than the guideline 10 inch/h (254 mm/h). The results are discussed with multiple stakeholders that participated in ClimateCafe New Orleans. Whether the results are considered unacceptable depends on a number of factors, including its intended purpose, site specific characteristics and most of all stakeholder expectations and perceptions. The designing, planning and scheduling of maintenance requirements for green infrastructure by stormwater managers can be carried out with more confidence so that green infrastructure will continue to perform satisfactorily over the intended design life and can mitigate the effects of heavy rainfall and droughts in the future.
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Infiltrating pavements are potentially effective climate adaptation measures to counteract arising challenges related to flooding and drought in urban areas. However, they are susceptible to clogging causing premature degradation. As part of the Dutch Delta Plan, Dutch municipalities were encouraged to put infiltrating pavements into practice. Disappointing experiences made a significant number of municipalities decide, however, to stop further implementation. A need existed to better understand how infiltrating pavements function in practice. Through 81 full-scale infiltration tests, we investigated the performance of infiltrating pavements in practice. Most pavements function well above Dutch and international standards. However, variation was found to be high. Infiltration rates decrease over time. Age alone, however, is not a sufficient explanatory factor. Other factors, such as environmental or system characteristics, are of influence here. Maintenance can play a major role in preserving/improving the performance of infiltrating pavements in practice. While our results provide the first indication of the functioning of infiltrating pavement in practice, only with multi-year measurements following a strict monitoring protocol can the longer-term effects of environmental factors and maintenance actually be determined, providing the basis for the development of an optimal maintenance schedule and associated cost–benefit assessments to the added value of this type of climate adaptation.
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Het veranderende klimaat leidt tot extremere weerspatronen. Het KNMI heeft in een onderzoek geconcludeerd dat Nederland in de toekomst te maken krijgt met een stijgende zeespiegel, meer extreme neerslag, drogere zomers en meer extreme hitte.Al deze veranderingen hebben een grote impact op de leefomgeving en met name in het stedelijk gebied kan dit tot problemen gaan leiden. Steden zijn vaak sterk verhard en door verstedelijking neemt die verharding in en om steden steeds verder toe.Binnen het project de Infiltrerende Stad wordt gekeken naar hoe we deze verharding kunnen aanpassen aan het veranderende klimaat. Hiervoor kijken we specifiek n naar waterdoorlatende bestrating. Deze vorm van verharding is in staat om (een deel van) neerslag via de weg af te voeren. Hiermee kan wateroverlast door extreme regen deels voorkomen worden en water lokaal bewaard worden voor tijden van droogte.Het Project Infiltrerende Stad helpt ondernemers om meer inzicht te krijgen in de werking en het onderhoud van deze soort verharding zodat de werking op de lange termijn geborgd is. Het uiteindelijke doel is de toepassing van deze vorm van verharding in de stedelijke omgeving te bevorderen.
