scholarly journals Role of dams in reducing global flood exposure under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julien Boulange ◽  
Naota Hanasaki ◽  
Dai Yamazaki ◽  
Yadu Pokhrel
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Flood Risk ◽  
Impact Analysis ◽  
Flow Regulation ◽  
Flood Mitigation ◽  
Population Exposure ◽  
Flood Exposure ◽  
Future Population

AbstractGlobally, flood risk is projected to increase in the future due to climate change and population growth. Here, we quantify the role of dams in flood mitigation, previously unaccounted for in global flood studies, by simulating the floodplain dynamics and flow regulation by dams. We show that, ignoring flow regulation by dams, the average number of people exposed to flooding below dams amount to 9.1 and 15.3 million per year, by the end of the 21st century (holding population constant), for the representative concentration pathway (RCP) 2.6 and 6.0, respectively. Accounting for dams reduces the number of people exposed to floods by 20.6 and 12.9% (for RCP2.6 and RCP6.0, respectively). While environmental problems caused by dams warrant further investigations, our results indicate that consideration of dams significantly affect the estimation of future population exposure to flood, emphasizing the need to integrate them in model-based impact analysis of climate change.

Quantifying the effect of dams in reducing global flood exposure under climate change

2021 ◽  
Author(s):  
Julien Boulange ◽  
Naota Hanasaki ◽  
Dai Yamazaki ◽  
Yadu Pokhrel
Keyword(s):  
Climate Change ◽  
Flood Risk ◽  
Greenhouse Gas Emission ◽  
Hydrological Cycle ◽  
Climate Change Impacts ◽  
Flood Protection ◽  
Population Exposure ◽  
Water Regulation ◽  
Catchment Scale ◽  
Flood Exposure

<p>Flood risk was reported to increase in the future due to climate change and population growth. While recent and earlier studies have derived plausible climate change impacts on global flood risk, dams have never been explicitly implemented into simulation tools. Currently, about half of major river systems worldwide are regulated by dams and more than 3,700 major dams are planned or under construction. Consequently, to realistically assess population exposure to present and future floods, current and future dam landscapes must be integrated into existing flood modeling frameworks.</p><p>In this research, the role of dams on future flood risk under climate change is quantified by simulating the global hydrological cycle, including floodplain dynamics, and considering flow regulation by dams.</p><p> </p><p>The global population exposed to historical once-in-100-year floods in our simulation was 9.4 million people, relatively close to the estimate of 5.6 million people indicated in a previous study (Hirabayashi et al., 2013) and the Dartmouth Flood Observatory database which estimated this number as 11.9 million people. Downstream of dams, the number of people exposed to the historical once-in-100-year floods were 7.2 and 13.4 million on average over 2006–2099 given a low and a medium-high greenhouse gas emission trajectory (RCP2.6 and RCP6.0, respectively). By the end of the 21<sup>st</sup> century, the populations exposed to flooding below dams decreased on average by 20.6% and 12. 9% for the two trajectories compared to simulations not accounting for the flow regulations produced by dams.</p><p>At the catchment scale, by considering water regulation in densely populated and heavily water regulated catchments, the occurrence of flood events largely decreases compared to projections not accounting for water regulation. Over the 2070–2099 period and for 14 catchments, the annual flooded area shrank by, on average (first and third quartiles given in bracket), 22.5% (19.8–40.5) and 25.9% (12.1–34.5) for RCP2.6 and RCP6.0 respectively.</p><p>To maintain the levels of flood protection that dams have provided, new dam operations will be required to offset the effect of climate change, possibly negatively affecting energy production and water storage. In addition, precise and reliable hydro-meteorological forecasts will be invaluable for enhancing flood protection and avoid excessive outflows. Given the many negative environmental and social impacts of dams, comprehensive assessments that consider both potential benefits and adverse effects are necessary for the sustainable development of water resources.</p>

The Impact of Perceived Flood Exposure on Flood-Risk Perception: The Role of Distance

Risk Analysis ◽  
2016 ◽  
Vol 36 (11) ◽  
pp. 2158-2186 ◽  
Author(s):  
Eoin O'Neill ◽  
Finbarr Brereton ◽  
Harutyun Shahumyan ◽  
J. Peter Clinch
Keyword(s):  
Risk Perception ◽  
Flood Risk ◽  
Flood Exposure ◽  
The Impact ◽  
Flood Risk Perception

Assessment and Adaptation to Climate Change-Related Flood Risks

2018 ◽  
Author(s):  
Brenden Jongman ◽  
Hessel C. Winsemius ◽  
Stuart A. Fraser ◽  
Sanne Muis ◽  
Philip J. Ward
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Risk Management ◽  
Population Growth ◽  
Sea Level ◽  
Flood Risk ◽  
Management Strategies ◽  
Inundation Depth ◽  
Risk Management Strategies ◽  
Flood Losses

The flooding of rivers and coastlines is the most frequent and damaging of all natural hazards. Between 1980 and 2016, total direct damages exceeded $1.6 trillion, and at least 225,000 people lost their lives. Recent events causing major economic losses include the 2011 river flooding in Thailand ($40 billion) and the 2013 coastal floods in the United States caused by Hurricane Sandy (over $50 billion). Flooding also triggers great humanitarian challenges. The 2015 Malawi floods were the worst in the country’s history and were followed by food shortage across large parts of the country. Flood losses are increasing rapidly in some world regions, driven by economic development in floodplains and increases in the frequency of extreme precipitation events and global sea level due to climate change. The largest increase in flood losses is seen in low-income countries, where population growth is rapid and many cities are expanding quickly. At the same time, evidence shows that adaptation to flood risk is already happening, and a large proportion of losses can be contained successfully by effective risk management strategies. Such risk management strategies may include floodplain zoning, construction and maintenance of flood defenses, reforestation of land draining into rivers, and use of early warning systems. To reduce risk effectively, it is important to know the location and impact of potential floods under current and future social and environmental conditions. In a risk assessment, models can be used to map the flow of water over land after an intense rainfall event or storm surge (the hazard). Modeled for many different potential events, this provides estimates of potential inundation depth in flood-prone areas. Such maps can be constructed for various scenarios of climate change based on specific changes in rainfall, temperature, and sea level. To assess the impact of the modeled hazard (e.g., cost of damage or lives lost), the potential exposure (including buildings, population, and infrastructure) must be mapped using land-use and population density data and construction information. Population growth and urban expansion can be simulated by increasing the density or extent of the urban area in the model. The effects of floods on people and different types of buildings and infrastructure are determined using a vulnerability function. This indicates the damage expected to occur to a structure or group of people as a function of flood intensity (e.g., inundation depth and flow velocity). Potential adaptation measures such as land-use change or new flood defenses can be included in the model in order to understand how effective they may be in reducing flood risk. This way, risk assessments can demonstrate the possible approaches available to policymakers to build a less risky future.

scholarly journals Impact of population growth and population ethics on climate change mitigation policy

2017 ◽  
Vol 114 (46) ◽  
pp. 12338-12343 ◽  
Author(s):  
Noah Scovronick ◽  
Mark B. Budolfson ◽  
Francis Dennig ◽  
Marc Fleurbaey ◽  
Asher Siebert ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Growth ◽  
Cost Savings ◽  
Population Means ◽  
Development Policies ◽  
Climate Change Mitigation Policy ◽  
Lower Fertility ◽  
The Difference ◽  
Near Term ◽  
Future Population

Future population growth is uncertain and matters for climate policy: higher growth entails more emissions and means more people will be vulnerable to climate-related impacts. We show that how future population is valued importantly determines mitigation decisions. Using the Dynamic Integrated Climate-Economy model, we explore two approaches to valuing population: a discounted version of total utilitarianism (TU), which considers total wellbeing and is standard in social cost of carbon dioxide (SCC) models, and of average utilitarianism (AU), which ignores population size and sums only each time period’s discounted average wellbeing. Under both approaches, as population increases the SCC increases, but optimal peak temperature decreases. The effect is larger under TU, because it responds to the fact that a larger population means climate change hurts more people: for example, in 2025, assuming the United Nations (UN)-high rather than UN-low population scenario entails an increase in the SCC of 85% under TU vs. 5% under AU. The difference in the SCC between the two population scenarios under TU is comparable to commonly debated decisions regarding time discounting. Additionally, we estimate the avoided mitigation costs implied by plausible reductions in population growth, finding that large near-term savings ($billions annually) occur under TU; savings under AU emerge in the more distant future. These savings are larger than spending shortfalls for human development policies that may lower fertility. Finally, we show that whether lowering population growth entails overall improvements in wellbeing—rather than merely cost savings—again depends on the ethical approach to valuing population.

scholarly journals Water-level attenuation in broad-scale assessments of exposure to coastal flooding: a sensitivity analysis

2018 ◽  
Author(s):  
Athanasios T. Vafeidis ◽  
Mark Schuerch ◽  
Claudia Wolff ◽  
Tom Spencer ◽  
Jan L. Merkens ◽  
...  
Keyword(s):  
Water Level ◽  
Flood Risk ◽  
Land Surface ◽  
Surface Characteristics ◽  
Water Levels ◽  
Risk Indicators ◽  
Population Exposure ◽  
Modelling Framework ◽  
Complex Interactions ◽  
Flood Exposure

Abstract. This study explores the uncertainty introduced in global assessments of coastal flood exposure and risk when not accounting for water level attenuation due to land-surface characteristics. We implement a range of plausible water-level attenuation values for characteristic land-cover classes in the flood module of the Dynamic and Integrated Vulnerability Assessment (DIVA) modelling framework and assess the sensitivity of flood exposure and flood risk indicators to differences in attenuation rates. Results show a reduction of up to 47 % in area exposure and even larger reductions in population exposure and expected flood damages when considering water level attenuation. The reductions vary by country, reflecting the differences in the physical characteristics of the floodplain as well as in the spatial distribution of people and assets in coastal regions. We find that uncertainties related to not accounting for water attenuation in global assessments of flood risk are of similar magnitude to the uncertainties related to the amount of SLR expected over the 21st century. Despite using simplified assumptions to account for the process of water level attenuation, which depends on numerous factors and their complex interactions, our results strongly suggest that an improved understanding and representation of the temporal and spatial variation of water levels across floodplains is essential for future impact modelling.

Saudi demographics may ultimately drive discontent

2021 ◽  
Keyword(s):  
Climate Change ◽  
Social Change ◽  
Population Growth ◽  
Brain Drain ◽  
Rural Areas ◽  
Short Term ◽  
Content Type ◽  
Economic Role ◽  
Role Of Religion

Significance This means the leadership must manage a significant social change, catalysed by an engaged and 'globalised' youth segment. At the same time, the economy has to accommodate population growth even as its hydrocarbon base faces uncertainties from climate change. Impacts Beyond major urban centres such as Riyadh and Jeddah, much of the country will remain closed and conservative. Moves to curb the influence of the clerical establishment will persist, but the central role of religion will prove resistant to change. In the short term, women’s rising economic role will disrupt familial norms only among the elite. The current shrinking space for expressing discontent could contribute to a brain drain from the kingdom. By 2035, there will be a higher likelihood of protests, both virtual and physical, especially in rural areas.

Role of biotechnology to meet 2050 global demand of population growth in the current situation of livestock challenge in the Developing country: A Review

2019 ◽  
Vol 10 (06) ◽  
pp. 1540-1547
Author(s):  
Misikir Mengistu ◽  
Praveen Yadav ◽  
Lema Gemeda
Keyword(s):  
Climate Change ◽  
United Nations ◽  
Population Growth ◽  
Soil Fertility ◽  
Land Degradation ◽  
Human Population ◽  
Daily Intake ◽  
Production Sector ◽  
Global Demand

Nowadays the facts indicate that’s the human population rise 7.7 billion as of April 2019 according to the most recent United Nations estimates elaborated by World meters beside the burden of demand daily on the production sector of livestock which hindered by the consequences of overpopulation and climate change that pushes land degradation, decrease in soil fertility which are challenges of getting recommended animal daily intake basically feed.

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