Climate Change Impact on Flood Control Measures for Highly Populated Urban Watershed

Flooding and overflows are recurring problems in several Brazilian cities, which usually undergo disorderly development. Their causes vary from increased impervious surface areas, deficiency/inefficiency of drainage structures and their maintenance, siltation of rivers, channel obstructions, and climatic factors. This situation is aggravated in the major cities. The Anhangabau watershed lies in the central portion of the city of Sao Paulo – Brazil and covers a drainage area of 5.4 km². The region is highly urbanized and crossed by a major north-south road connection. During heavy rain events, portions of this interconnection passage become compromised, disrupting the flow of vehicles, creating a chaotic situation for the population, as well as losses to the national economy. Observed rainfall records and an existing IDF (intensity duration frequency) curve for the region are used to obtain design storms. To account for climate change, a well know procedure, the equidistance quantile matching method for updating IDF curves under climate change, was applied to the existing historical data. Several different global climate models (GCM) and one regional model were applied to obtain and update rainfall design storm. The GCMs and future scenarios used were from the IPCC Assessment Report 5 (AR5) and two future projections: RCP (representative concentration pathway) 4.5 and 8.5. Alternatives previously proposed to solve to flooding issue are briefly reviewed. On one of the latest studies [1], a few modern concepts of water resources management are presented, and the linear retention measure was found to offer higher potential to mitigate the flooding problem in the lower valley of the watershed. Therefore, this alternative was used to evaluate different design storms scenarios combined with return periods of 25 and 100-years as well as the updated IDF under climate change for RCP 4.5 and RCP 8.5. To model the complex network, representing both road and drainage systems and their interconnections, PCSWMM/SWMM software was applied. Results are presented as flooding maps and show the impacts of the proposed linear retention measure based on the existing IDF curves and the updated IDF curves under climate change for two different drainage system conditions, current and improved with the use of linear retention reservoirs. Results show that the prosed changes on the drainage system help reduce the risk and damage to flooding. The climate change scenarios, however, impose a significant threat and need immediate attention from city planners and stakeholders.

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Climate Change Impacts and Flood Control Measures for Highly Developed Urban Watersheds

Water ◽

10.3390/w10070829 ◽

2018 ◽

Vol 10 (7) ◽

pp. 829 ◽

Cited By ~ 11

Author(s):

Carla da Silva ◽

Andre Schardong ◽

Joaquin Garcia ◽

Cristiano Oliveira

Keyword(s):

Climate Change ◽

Flood Control ◽

Climate Models ◽

Climatic Factors ◽

Low Impact Development ◽

Global Climate Models ◽

Control Measures ◽

Mitigation Measures ◽

Climate Change Scenarios ◽

Idf Curves

Flooding and overflow are recurring problems in several Brazilian cities, which usually face disorderly development. The causes vary, and include increased impervious surface areas, deficiency/inefficiency of drainage structures and lack of maintenance, siltation of rivers, channel obstructions, and climatic factors. In this paper, we present an analysis of mitigation measures to minimize flooding in a watershed located in the core of the city of São Paulo, the biggest city with the highest gross domestic product (GDP) in Brazil. Observed rainfall records and existing intensity duration frequency (IDF) curves for the region are used to obtain design storms. To account for climate change, the equidistance quantile matching method for updating IDF curves under climate change, a well-known procedure, was applied to the existing historical data. Several different global climate models (GCMs) and one regional model were applied to obtain and update rainfall design storms. The GCMs and future scenarios used were from Intergovernmental Panel on Climate Change—IPCC Assessment Report 5 (AR5) and two future projections—representative concentration pathway (RCP) 4.5 and 8.5. Spatially distributed reservoirs combined with low-impact development (LID) measures were used to evaluate different design storm scenarios combined with return periods of 25 and 100 years as well as the updated IDF under climate change for RCP 4.5 and RCP 8.5. Results show that the proposed changes to the drainage system can help reduce the risk and damage of flooding. The climate change scenarios, however, impose a significant threat and need immediate attention from city planners and stakeholders.

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Disaggregation of future GCMs to generate IDF curves for the assessment of urban floods

Journal of Water and Climate Change ◽

10.2166/wcc.2021.241 ◽

2021 ◽

Author(s):

H. Tayşi ◽

M. Özger

Keyword(s):

Climate Change ◽

Short Duration ◽

Urban Areas ◽

Climate Models ◽

Global Climate ◽

Drainage System ◽

Global Climate Models ◽

Urban Floods ◽

Idf Curves ◽

Intensity Duration Frequency

Abstract Urbanization and industrialization cause an increase in greenhouse gas emissions, which in turn causes changes in the atmosphere. Climate change is causing extreme rainfalls and these rainfalls are getting stronger day after day. Floods are threatening urban areas, and short-duration rainfall and outdated drainages are responsible for urban floods. Intensity–Duration–Frequency (IDF) curves are crucial for both drainage system design and assessment of flood risk. Once IDF curves are determined from historical data, they are assumed to be stationary. However, IDF curves must be non-stationary and time varying based on preparation for extreme events. This study generates future IDF curves with short-duration rainfalls under climate change. To represent future rainfall, an ensemble of four Global Climate Models generated under Representative Concentration Pathways (RCP) 4.5 and 8.5 were used in this study. A new approach to the HYETOS disaggregation model was applied to disaggregate daily future rainfall into sub-hourly using disaggregation parameters of hourly measured rainfalls. Hence, sub-hourly future rainfalls will be obtained capturing historical rainfall patterns instead of random rainfall characteristics. Finally, historical and future IDF curves were compared. The study concludes that increases in short-duration rainfalls will be highly intensified in both the near and distant futures with a high probability.

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Projecting heat-related excess mortality under climate change scenarios in China

Nature Communications ◽

10.1038/s41467-021-21305-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jun Yang ◽

Maigeng Zhou ◽

Zhoupeng Ren ◽

Mengmeng Li ◽

Boguang Wang ◽

...

Keyword(s):

Climate Change ◽

Excess Mortality ◽

Climate Models ◽

Global Climate ◽

Specific Effect ◽

Northern China ◽

The Elderly ◽

Population Ageing ◽

Global Climate Models ◽

Climate Change Scenarios

AbstractRecent studies have reported a variety of health consequences of climate change. However, the vulnerability of individuals and cities to climate change remains to be evaluated. We project the excess cause-, age-, region-, and education-specific mortality attributable to future high temperatures in 161 Chinese districts/counties using 28 global climate models (GCMs) under two representative concentration pathways (RCPs). To assess the influence of population ageing on the projection of future heat-related mortality, we further project the age-specific effect estimates under five shared socioeconomic pathways (SSPs). Heat-related excess mortality is projected to increase from 1.9% (95% eCI: 0.2–3.3%) in the 2010s to 2.4% (0.4–4.1%) in the 2030 s and 5.5% (0.5–9.9%) in the 2090 s under RCP8.5, with corresponding relative changes of 0.5% (0.0–1.2%) and 3.6% (−0.5–7.5%). The projected slopes are steeper in southern, eastern, central and northern China. People with cardiorespiratory diseases, females, the elderly and those with low educational attainment could be more affected. Population ageing amplifies future heat-related excess deaths 2.3- to 5.8-fold under different SSPs, particularly for the northeast region. Our findings can help guide public health responses to ameliorate the risk of climate change.

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Future Climate Change Scenarios for Asia as Inferred from Selected Coupled Atmosphere-ocean Global Climate Models.

Journal of the Meteorological Society of Japan Ser II ◽

10.2151/jmsj.79.219 ◽

2001 ◽

Vol 79 (1) ◽

pp. 219-227 ◽

Cited By ~ 35

Author(s):

Murari Lal ◽

Hideo Harasawa

Keyword(s):

Climate Change ◽

Climate Models ◽

Global Climate ◽

Global Climate Models ◽

Future Climate ◽

Future Climate Change ◽

Climate Change Scenarios

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Uncertainties in Riverine and Coastal Flood Impacts under Climate Change

Water ◽

10.3390/w13131774 ◽

2021 ◽

Vol 13 (13) ◽

pp. 1774

Author(s):

Shuyi Wang ◽

Mohammad Reza Najafi ◽

Alex J. Cannon ◽

Amir Ali Khan

Keyword(s):

Climate Change ◽

Climate Models ◽

Climate Model ◽

Global Climate ◽

Block Design ◽

Coastal Flooding ◽

Hydrologic Model ◽

Global Climate Models ◽

Storm Events ◽

Idf Curves

Climate change can affect different drivers of flooding in low-lying coastal areas of the world, challenging the design and planning of communities and infrastructure. The concurrent occurrence of multiple flood drivers such as high river flows and extreme sea levels can aggravate such impacts and result in catastrophic damages. In this study, the individual and compound effects of riverine and coastal flooding are investigated at Stephenville Crossing located in the coastal-estuarine region of Newfoundland and Labrador (NL), Canada. The impacts of climate change on flood extents and depths and the uncertainties associated with temporal patterns of storms, intensity–duration–frequency (IDF) projections, spatial resolution, and emission scenarios are assessed. A hydrologic model and a 2D hydraulic model are set up and calibrated to simulate the flood inundation for the historical (1976–2005) as well as the near future (2041–2070) and far future (2071–2100) periods under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Future storm events are generated based on projected IDF curves from convection-permitting Weather Research and Forecasting (WRF) climate model simulations, using SCS, Huff, and alternating block design storm methods. The results are compared with simulations based on projected IDF curves derived from statistically downscaled Global Climate Models (GCMs). Both drivers of flooding are projected to intensify in the future, resulting in higher risks of flooding in the study area. Compound riverine and coastal flooding results in more severe inundation, affecting the communities on the coastline and the estuary area. Results show that the uncertainties associated with storm hyetographs are considerable, which indicate the importance of accurate representation of storm patterns. Further, simulations based on projected WRF-IDF curves show higher risks of flooding compared to the ones associated with GCM-IDFs.

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The challenge of combining initialised and uninitialised decadal projections

10.5194/egusphere-egu2020-7313 ◽

2020 ◽

Author(s):

James Murphy

Keyword(s):

Climate Change ◽

Climate Models ◽

Global Climate ◽

Global Climate Models ◽

Climate Change Scenarios ◽

Internal Climate Variability ◽

Climate Risks ◽

Early Results ◽

Ensemble Mean ◽

Decadal Climate

The challenge of combining initialised and uninitialised decadal projectionsJames Murphy, Robin Clark, Nick Dunstone, Glen Harris, Leon Hermanson and Doug SmithDuring the past 10 years or so, exploratory work in initialised decadal climate prediction, using global climate models started from recent analyses of observations, has grown into a coordinated international programme that contributes to IPCC assessments. At the same time, countries have continued to develop and update their national climate change scenarios.&#160; These typically cover the full 21st century, including the initial decade that overlaps with the latest initialised forecasts. To date, however, national scenarios continue to be based exclusively on long-term (uninitialised) climate change simulations, with initialised information regarded as a separate stream of information.We will use early results from the latest UK national scenarios (UKCP), and the latest CMIP6 initialised predictions, to illustrate the potential and challenges associated with the notion of combining both streams of information. This involves assessing the effects of initialisation on predictability and uncertainty (as indicated, for example, by the skill of ensemble-mean forecasts and the spread amongst constituent ensemble members). Here, a particular challenge involves interpretation of the &#8220;signal-to-noise&#8221; problem, in which ensemble-mean skill can sometimes be found which is larger than would be expected on the basis of the ensemble spread. In addition to initialisation, we will also emphasise the importance of understanding how the assessment of climate risks depends on other features of prediction system design, including the sampling of model uncertainties and the simulation of internal climate variability.

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Assessment of vulnerability of river basins in Ghana to water stress conditions under climate change

Journal of Water and Climate Change ◽

10.2166/wcc.2012.030 ◽

2012 ◽

Vol 3 (4) ◽

pp. 276-286 ◽

Cited By ~ 8

Author(s):

Emmanuel Obuobie ◽

Kwabena Kankam-Yeboah ◽

Barnabas Amisigo ◽

Yaw Opoku-Ankomah ◽

Deborah Ofori

Keyword(s):

Climate Change ◽

Water Stress ◽

Water Resources ◽

Water Scarcity ◽

Climate Models ◽

Assessment Tool ◽

River Basins ◽

Global Climate Models ◽

Control Measures ◽

Basin Surface

The Falkenmark indicator was used to assess vulnerability of the White Volta (106,000 km2) and Pra (20,023 km2) river basins in Ghana to water stress under climate change for the periods 2006–2035 (representing the 2020s) and 2036–2065 (2050s). The indicator is a commonly used measure of water stress and defines thresholds of 1,700, 1,000 and 500 m3/capita/annum as water stress, water scarcity and absolute scarcity, respectively. Downscaled data from ensemble averages of two global climate models, ECHAM4 and CSIRO, were used to drive the Soil and Water Assessment Tool for estimation of basin surface water resources under climate change. The simulated water resources in the two basins showed significant reduction of 22% for 2020. Further reductions were estimated for 2050 (50% and 46% for the White Volta and Pra, respectively). Without climate change, the White Volta basin will attain water stress and water scarcity by 2020 and 2050, respectively; the Pra is already water stressed and expected to worsen to water scarcity by 2020 and absolute scarcity by 2050. Climate change will aggravate the conditions in both basins. Implementation of integrated water resources management and population control measures are recommended for sustainable use and management of water resources in both basins.

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Impact of Climate Change on the Hydrology of the Forested Watershed That Drains to Lake Erken in Sweden: An Analysis Using SWAT+ and CMIP6 Scenarios

Forests ◽

10.3390/f12121803 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1803

Author(s):

Inmaculada C. Jiménez-Navarro ◽

Patricia Jimeno-Sáez ◽

Adrián López-Ballesteros ◽

Julio Pérez-Sánchez ◽

Javier Senent-Aparicio

Keyword(s):

Climate Change ◽

Climate Models ◽

Snow Water Equivalent ◽

Hydrological Cycle ◽

Global Climate ◽

Water Discharge ◽

Global Climate Models ◽

Climate Change Scenarios ◽

Case Scenario ◽

Worst Case

Precipitation and temperature around the world are expected to be altered by climate change. This will cause regional alterations to the hydrological cycle. For proper water management, anticipating these changes is necessary. In this study, the basin of Lake Erken (Sweden) was simulated with the recently released software SWAT+ to study such alterations in a short (2026–2050), medium (2051–2075) and long (2076–2100) period, under two different climate change scenarios (SSP2-45 and SSP5-85). Seven global climate models from the latest projections of future climates that are available (CIMP 6) were compared and ensembled. A bias-correction of the models’ data was performed with five different methods to select the most appropriate one. Results showed that the temperature is expected to increase in the future from 2 to 4 °C, and precipitation from 6% to 20%, depending on the scenario. As a result, water discharge would also increase by about 18% in the best-case scenario and by 50% in the worst-case scenario, and the surface runoff would increase between 5% and 30%. The floods and torrential precipitations would also increase in the basin. This trend could lead to soil impoverishment and reduced water availability in the basin, which could damage the watershed’s forests. In addition, rising temperatures would result in a 65% reduction in the snow water equivalent at best and 92% at worst.

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Seasonal and Long-Term Changes to Pavement Life Caused by Rising Temperatures from Climate Change

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198119844249 ◽

2019 ◽

Vol 2673 (6) ◽

pp. 267-278 ◽

Cited By ~ 3

Author(s):

Jayne F. Knott ◽

Jo E. Sias ◽

Eshan V. Dave ◽

Jennifer M. Jacobs

Keyword(s):

Climate Change ◽

Temperature Rise ◽

Climate Models ◽

Global Climate ◽

Global Climate Models ◽

Climate Change Scenarios ◽

Top Down ◽

Bottom Up ◽

Pavement Damage ◽

The Impact

Pavements are vulnerable to reduced life with climate-change-induced temperature rise. Greenhouse gas emissions have caused an increase in global temperatures since the mid-20th century and the warming is projected to accelerate. Many studies have characterized this risk with a top-down approach in which climate-change scenarios are chosen and applied to predict pavement-life reduction. This approach is useful in identifying possible pavement futures but may miss short-term or seasonal pavement-response trends that are essential for adaptation planning. A bottom-up approach focuses on a pavement’s response to incremental temperature change resulting in a more complete understanding of temperature-induced pavement damage. In this study, a hybrid bottom-up/top-down approach was used to quantify the impact of changing pavement seasons and temperatures on pavement life with incremental temperature rise from 0 to 5°C at a site in coastal New Hampshire. Changes in season length, seasonal average temperatures, and temperature-dependent resilient modulus were used in layered-elastic analysis to simulate the pavement’s response to temperature rise. Projected temperature rise from downscaled global climate models was then superimposed on the results to determine the timing of the effects. The winter pavement season is projected to end by mid-century, replaced by a lengthening fall season. Seasonal pavement damage, currently dominated by the late spring and summer seasons, is projected to be distributed more evenly throughout the year as temperatures rise. A 7% to 32% increase in the asphalt-layer thickness is recommended to protect the base and subgrade with rising temperatures from early century to late-mid-century.

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Decomposing the uncertainties in global drought projection

10.5194/egusphere-egu21-6780 ◽

2021 ◽

Author(s):

Yusuke Satoh ◽

Hideo Shiogama ◽

Naota Hanasaki ◽

Yadu Pokhrel ◽

Julien Boulange ◽

...

Keyword(s):

Climate Change ◽

Climate Models ◽

Global Climate ◽

Global Climate Models ◽

Dominant Factor ◽

Climate Change Scenarios ◽

Relative Importance ◽

Main Factors ◽

Global Water ◽

Uncertainty Source

Droughts are anticipated to intensify or become more frequent in many parts of the world due to climate change. However, the issue of drought definition, namely the diversity of drought definition, makes it difficult to compare drought projections and hampers overviewing future changes in drought. This issue is widely known and underscored in recent reports of the Intergovernmental Panel on Climate Change, but the relative importance of the issue and its spatial distribution have never been quantitatively evaluated compared to other sources of uncertainty.Here, using a multi-scenario and multi-model dataset with combinations of three climate change scenarios, four global climate models and seven global water models, we evaluated changes in the frequency of three categories of drought (meteorological, agricultural, and hydrological droughts) by a consistent standardized approach with four different temporal scales of accumulation periods to show how differences among the drought definitions could result in critical uncertainties. For simplicity, this study focuses on one drought index per drought category. Firstly we investigated the disagreement in the sign of changes between definitions, and then we decomposed the overall uncertainty to estimate the relative importance of each source of uncertainty. By a multifactorial ANOVA, uncertainty was decomposed into four main factors, namely drought definitions, climate change scenarios, global climate models and global water impact models, and their interactions.Our results highlight specific regions where the sign of change disagrees between drought definitions. Importantly, changes in drought frequency in such regions tended to be statistically insignificant with low ensemble member agreement. Drought definition attributed to18% of the main factor uncertainty at the global scale, and the definition was the dominant uncertainty source over 11% of the global land area. The contribution of difference in the drought category showed a higher contribution to overall uncertainty than the difference in scales. The contribution of scenario uncertainty was the least among the main factors in general, though it is a dominant factor in the far-future in a couple of hotspot regions such as the Mediterranean region. Overall, model uncertainties were the primary source of uncertainty, and the definition issue was less important over large areas. However, definition uncertainty was the primal uncertainty source with significant changes in particular regions, such as parts of high-latitude areas in the northern hemisphere. One needs to pay attention to these regions in overviewing future drought change. Nonetheless, what this study quantified is the relative importance of uncertainty stemming from drought definition that should be avoidable or reducible if one treats drought specifically. Our results indicate that we can reduce uncertainty in drought projections to some extent and get a clearer picture by clarifying hydrological processes or sectors of interest.

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