Review for "Increase in urban flood risk resulting from climate change - The role of storm temporal patterns" by Hettiarachchi et al.

2017 ◽  
Author(s):  
Anonymous
2017 ◽  
Author(s):  
Suresh Hettiarachchi ◽  
Conrad Wasko ◽  
Ashish Sharma

Abstract. Warming temperatures are causing extreme rainfall to intensify resulting in increased risk of flooding in developed areas. Quantifying this increased risk is of critical importance for the protection of life and property as well as for infrastructure planning and design. The study presented in this manuscript uses a comprehensive hydrologic and hydraulic model of a fully developed urban/suburban catchment to explore two primary questions related to climate change impacts on flood risk: (1) How does climate change effects on storm temporal patterns and rainfall volumes impact flooding in a developed complex watershed? (2) Is the storm temporal pattern as critical as the total volume of rainfall when evaluating urban flood risk? The updated NOAA Atlas 14 intensity–duration–frequency (IDF) relationships and temporal patterns, widely used in design and planning modelling in the USA, form the basis of the assessment reported here. Current literature shows that a rise in temperature will result in intensification of rainfall. These impacts are not explicitly included in the NOAA temporal patterns, which can have consequences on the design and planning of adaptation measures. We use the expected increase in temperature for the RCP8.5 scenario for 2081–2100, to project temporal patterns and rainfall volumes to reflect future climatic change. The modelling analysis for a 22 km2 developed watershed show that temporal patterns cause substantial variability in flood depths during a storm event. The changes in the projected temporal patterns alone increase the risk of flood magnitude between 1 to 35 % with the cumulative impacts of temperature rise on temporal pattern and the storm volume increasing flood risk by between 10 to 170 % across the locations that were referenced for a 50 year return period storm. The variability in catchment response to temporal patterns show that regional storage facilities are sensitive to rainfall patterns that are loaded at the latter part of the storm duration while the short duration extremely intense storms will cause extensive flooding at all locations. This study shows that changes in temporal patterns will have a significant impact on urban/suburban catchment response and need to be carefully considered and adjusted to account for climate change when used for design and planning future stormwater systems.


10.1596/25112 ◽  
2016 ◽  
Author(s):  
Salman Anees Soz ◽  
Jolanta Kryspin-Watson ◽  
Zuzana Stanton-Geddes

2021 ◽  
Author(s):  
Emily O’Donnell

<p>As global cities rethink their approaches to urban flood risk and water management in response to climate change, accelerating urbanisation and reductions in public green space, Blue-Green Infrastructure (BGI) is gaining increasing recognition due to the advantages of multifunctional BGI solutions over traditional piped drainage and grey infrastructure. BGI, including green and blue roofs, swales, rain gardens, street trees, ponds, urban wetlands, restored watercourses, reconnected floodplains, and re-naturalised rivers, is designed to turn ‘blue’ (or ‘bluer’) during rainfall events in order to reduce urban flood risk. In addition to managing flood risk and increasing water security, BGI generates a range of socio-cultural, economic and environmental co-benefits that help city authorities tackle other urban challenges and ultimately improve the quality of life of city dwellers.</p><p>Extensive research over the last decade has focused on improving knowledge of BGI systems in several broad areas, including: hydrological and hydraulic modelling of water flow through BGI assets; biochemical assessments of sediment and water quality; public preferences; identification and evaluation of BGI co-benefits, and; BGI planning and governance. Emerging research into adaptation pathways, natural capital accounting and social practice approaches for understanding community preferences demonstrate how BGI research is moving beyond hydrodynamic modelling to explore decision making under future uncertainty and placing greater emphasis on the role of community preferences in designing BGI that is accepted and supported by those who directly benefit.</p><p>This presentation will explore these emerging research areas, particularly focusing on the need for interdisciplinary research into BGI to enable the challenges and opportunities to be fully appreciated. Current knowledge gaps that present research opportunities in BGI will also be discussed, including the need for rigorous assessment criteria to determine the success of multifunctional BGI systems; greater investigation of the social benefits of BGI and the value people place on different types of BGI; the role of implicit perceptions in designing BGI assets, and; the role of urban watercourses as multifunctional BGI corridors able to safely convey stormwater while boosting water quality, providing multiple urban pathways (active transport, wildlife movements, etc.) and increasing green space in cities.</p>


2021 ◽  
Vol 13 (2) ◽  
pp. 262
Author(s):  
Huu Duy Nguyen ◽  
Dennis Fox ◽  
Dinh Kha Dang ◽  
Le Tuan Pham ◽  
Quan Vu Viet Du ◽  
...  

Flood risk is a significant challenge for sustainable spatial planning, particularly concerning climate change and urbanization. Phrasing suitable land planning strategies requires assessing future flood risk and predicting the impact of urban sprawl. This study aims to develop an innovative approach combining land use change and hydraulic models to explore future urban flood risk, aiming to reduce it under different vulnerability and exposure scenarios. SPOT-3 and Sentinel-2 images were processed and classified to create land cover maps for 1995 and 2019, and these were used to predict the 2040 land cover using the Land Change Modeler Module of Terrset. Flood risk was computed by combining hazard, exposure, and vulnerability using hydrodynamic modeling and the Analytic Hierarchy Process method. We have compared flood risk in 1995, 2019, and 2040. Although flood risk increases with urbanization, population density, and the number of hospitals in the flood plain, especially in the coastal region, the area exposed to high and very high risks decreases due to a reduction in poverty rate. This study can provide a theoretical framework supporting climate change related to risk assessment in other metropolitan regions. Methodologically, it underlines the importance of using satellite imagery and the continuity of data in the planning-related decision-making process.


2016 ◽  
Vol 161 ◽  
pp. 2241-2246 ◽  
Author(s):  
Erik Zimmermann ◽  
Laura Bracalenti ◽  
Rubén Piacentini ◽  
Luis Inostroza

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