scholarly journals Brief communication: The role of using precipitation or river discharge data when assessing global coastal compound flooding

2020 ◽  
Vol 20 (6) ◽  
pp. 1765-1782 ◽  
Author(s):  
Emanuele Bevacqua ◽  
Michalis I. Vousdoukas ◽  
Theodore G. Shepherd ◽  
Mathieu Vrac
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Storm Surges ◽  
High Water ◽  
Small Rivers ◽  
Water Runoff ◽  
Discharge Data ◽  
Physical Mechanisms ◽  
Catchment Size ◽  
The Impact

Abstract. Interacting storm surges and high water runoff can cause compound flooding (CF) in low-lying coasts and river estuaries. The large-scale CF hazard has been typically studied using proxies such as the concurrence of storm surge extremes either with precipitation or with river discharge extremes. Here the impact of the choice of such proxies is addressed employing state-of-the-art global datasets. Although they are proxies of diverse physical mechanisms, we find that the two approaches show similar CF spatial patterns. On average, deviations are smaller in regions where assessing the actual CF is more relevant, i.e. where the CF potential is high. Differences between the two assessments increase with the catchment size, and our findings indicate that CF in long rivers (catchment ≳5–10×103 km2) should be analysed using river discharge data. The precipitation-based assessment allows for considering local-rainfall-driven CF and CF in small rivers not resolved by large-scale datasets.

scholarly journals Brief communication: The role of using precipitation or river discharge data when assessing global coastal compound flooding

2020 ◽  
Author(s):  
Emanuele Bevacqua ◽  
Michalis I. Vousdoukas ◽  
Theodore G. Shepherd ◽  
Mathieu Vrac
Keyword(s):  
River Discharge ◽  
Large Scale ◽  
Storm Surges ◽  
High Water ◽  
Small Rivers ◽  
Water Runoff ◽  
Discharge Data ◽  
Physical Mechanisms ◽  
Catchment Size ◽  
The Impact

Abstract. Interacting storm surges and high water-runoff can cause compound flooding (CF) in low-lying coasts and river estuaries. The large-scale CF hazard has been typically studied using proxies such as the concurrence of storm surge extremes either with precipitation or with river discharge extremes. Here the impact of the choice of such proxies is addressed employing state-of-the-art global datasets. Although being proxies of diverse physical mechanisms, we find that the two approaches show similar CF spatial patterns. However, deviations increase with the catchment size and our findings indicate that CF in long rivers (catchment ≳ 5–10 000 Km2) is more accurately analysed using river discharge data. The precipitation-based assessment allows for considering local rainfall-driven CF, and CF in small rivers not resolved by large-scale datasets.

The Study of the Impact for Coastal Engineering on High Water Level Induced by Storm Surges in Bohai Bay

2011 ◽  
Vol 94-96 ◽  
pp. 810-814
Author(s):  
Jin Shan Zhang ◽  
Wei Sheng Zhang ◽  
Chen Cheng ◽  
Lin Yun Sun
Keyword(s):  
Water Level ◽  
Storm Surge ◽  
Large Scale ◽  
Storm Surges ◽  
High Water ◽  
Coastal Engineering ◽  
Cold Wave ◽  
Bohai Bay ◽  
Ocean Engineering ◽  
The Impact

Bohai Bay is an semi-closed bay, the storm surge disaster is very serious in past. Now more and more large ocean engineering are built here, To study changes of storm surge induced by the construction of large-scale coastal engineering in Bohai Bay in present, 2D numerical storm surge model is established with large - medium - small model nested approach. The three most typical storms surges: 9216, 9711 and by cold wave in October 2003 are simulated in the condition of before and after implementation of planning projects in Bohai Bay. Changes of storm surge water level due to implementation of artificial projects are analysis in this paper.

scholarly journals Wavelet analysis of the Baltic region river runoff longh-term trends and fluctuations

2010 ◽  
Vol 64 (5-6) ◽  
pp. 229-235
Author(s):  
Andrejs Timuhins ◽  
Valērijs Rodinovs ◽  
Māris Kļaviņš
Keyword(s):  
Climate Change ◽  
Wavelet Analysis ◽  
River Runoff ◽  
River Discharge ◽  
Large Scale ◽  
High Water ◽  
Baltic Region ◽  
Discharge Regime ◽  
The Baltic ◽  
The Impact

Wavelet analysis of the Baltic region river runoff longh-term trends and fluctuations The study of changes in river discharge and flood regime can provide important information on climate change and its impacts. Wavelet analysis offers new possibilities to study changes of river discharge patterns in regard to periodical processes on a background of climate change. In this study wavelet analysis was used to study long-term changes of river discharge in the Baltic region. Periodic oscillations of discharge intensity, and low- and high-water flow years are common for the major rivers in the Eastern Baltic region. Main frequencies of river discharge were estimated to be 14, 28, 37 years for the studied rivers. Wavelet analysis allowed to identify similarities between the river discharge regime, and thus, the factors influencing it. Years of maximal and minimal discharges for major rivers were identified and the impact of large-scale atmospheric circulation processes on the river discharge was studied.

Improving SAR Altimeter processing over the coastal zone and inland waters - the ESA HYDROCOASTAL project

2021 ◽  
Author(s):  
David Cotton ◽  
Keyword(s):  
Coastal Zone ◽  
Test Data ◽  
River Discharge ◽  
Altimeter Data ◽  
Inland Waters ◽  
Data Sets ◽  
Data Set ◽  
Discharge Data ◽  
Processing Algorithms ◽  
The Impact

<p><strong>Introduction</strong></p><p>HYDROCOASTAL is a two year project funded by ESA, with the objective to maximise exploitation of SAR and SARin altimeter measurements in the coastal zone and inland waters, by evaluating and implementing new approaches to process SAR and SARin data from CryoSat-2, and SAR altimeter data from Sentinel-3A and Sentinel-3B. Optical data from Sentinel-2 MSI and Sentinel-3 OLCI instruments will also be used in generating River Discharge products.</p><p>New SAR and SARin processing algorithms for the coastal zone and inland waters will be developed and implemented and evaluated through an initial Test Data Set for selected regions. From the results of this evaluation a processing scheme will be implemented to generate global coastal zone and river discharge data sets.</p><p>A series of case studies will assess these products in terms of their scientific impacts.</p><p>All the produced data sets will be available on request to external researchers, and full descriptions of the processing algorithms will be provided</p><p> </p><p><strong>Objectives</strong></p><p>The scientific objectives of HYDROCOASTAL are to enhance our understanding  of interactions between the inland water and coastal zone, between the coastal zone and the open ocean, and the small scale processes that govern these interactions. Also the project aims to improve our capability to characterize the variation at different time scales of inland water storage, exchanges with the ocean and the impact on regional sea-level changes</p><p>The technical objectives are to develop and evaluate  new SAR  and SARin altimetry processing techniques in support of the scientific objectives, including stack processing, and filtering, and retracking. Also an improved Wet Troposphere Correction will be developed and evaluated.</p><p><strong>Project  Outline</strong></p><p>There are four tasks to the project</p><ul><li>Scientific Review and Requirements Consolidation: Review the current state of the art in SAR and SARin altimeter data processing as applied to the coastal zone and to inland waters</li> <li>Implementation and Validation: New processing algorithms with be implemented to generate a Test Data sets, which will be validated against models, in-situ data, and other satellite data sets. Selected algorithms will then be used to generate global coastal zone and river discharge data sets</li> <li>Impacts Assessment: The impact of these global products will be assess in a series of Case Studies</li> <li>Outreach and Roadmap: Outreach material will be prepared and distributed to engage with the wider scientific community and provide recommendations for development of future missions and future research.</li> </ul><p> </p><p><strong>Presentation</strong></p><p>The presentation will provide an overview to the project, present the different SAR altimeter processing algorithms that are being evaluated in the first phase of the project, and early results from the evaluation of the initial test data set.</p><p> </p>

scholarly journals Cryospheric Impacts of Soviet River Diversion Schemes

1984 ◽  
Vol 5 ◽  
pp. 61-68 ◽  
Author(s):  
T. Holt ◽  
P. M. Kelly ◽  
B. S. G. Cherry
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
River Discharge ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Concentration ◽  
Ice Concentration ◽  
The Arctic Ocean ◽  
The Impact

Soviet plans to divert water from rivers flowing into the Arctic Ocean have led to research into the impact of a reduction in discharge on Arctic sea ice. We consider the mechanisms by which discharge reductions might affect sea-ice cover and then test various hypotheses related to these mechanisms. We find several large areas over which sea-ice concentration correlates significantly with variations in river discharge, supporting two particular hypotheses. The first hypothesis concerns the area where the initial impacts are likely to which is the Kara Sea. Reduced riverflow is associated occur, with decreased sea-ice concentration in October, at the time of ice formation. This is believed to be the result of decreased freshening of the surface layer. The second hypothesis concerns possible effects on the large-scale current system of the Arctic Ocean and, in particular, on the inflow of Atlantic and Pacific water. These effects occur as a result of changes in the strength of northward-flowing gradient currents associated with variations in river discharge. Although it is still not certain that substantial transfers of riverflow will take place, it is concluded that the possibility of significant cryospheric effects and, hence, large-scale climate impact should not be neglected.

scholarly journals PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 261-266
Author(s):  
A.-L. Montreuil ◽  
M. Chen ◽  
A. Esquerré ◽  
R. Houthuys ◽  
R. Moelans ◽  
...  
Keyword(s):  
Management Practices ◽  
Morphological Changes ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Airborne Lidar ◽  
Coastline Change ◽  
The Mean ◽  
The Impact

<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>

scholarly journals Evolution of the northern Fujian coast under the impact of natural and anthropogenic forces, 1976–2017: an analysis of coastal monitoring and satellite images

2019 ◽  
Vol 2 (1) ◽  
pp. 72-86 ◽  
Author(s):  
Shuai Cong ◽  
Xiao Wu ◽  
Yong Zhang ◽  
Biying Xue ◽  
Houjie Wang
Keyword(s):  
Storm Surges ◽  
High Water ◽  
Scientific Basis ◽  
Extreme Weather Events ◽  
Coastal Protection ◽  
Coastal Monitoring ◽  
Practical Applications ◽  
Coastal Profile ◽  
The Impact ◽  
Sand Extraction

The province of Fujian on China’s southeast coast is severely impacted by typhoons. Based on coastal profile monitoring and 40 years of satellite data, this paper analyzed the response of coastal profiles to natural and anthropogenic forces along the northern part of Fujian’s coast. Results indicated that the pattern of coastal evolution differed largely on cross-shore profiles and longshore coastlines. Only a few sandy coasts were severely affected by extreme weather events in summer, such as typhoons and storm surges, which may result from the wind direction relative to the coast. The cross-shore profiles changed drastically while the mean high-water coastline remained stable. In contrast, anthropogenic forces had a dual effect due to artificial sand extraction and reclamation. Artificial sand extraction usually occurred on sandy coasts, resulting in a decrease in some local surface profiles of tens of centimeters to metres in two years. Reclamation had the main impact on muddy coasts, especially in bays, causing seaward progradation during the past 40 years. The impacts of human activities on muddy coasts were far greater than natural factors. Findings from our coastal monitoring study for both sandy and muddy coasts provide an important scientific basis for practical applications, such as Fujian coastal protection, coastal zone exploitation, and utilization planning.

Changes in Latvian river discharge regime at the turn of the century

2012 ◽  
Vol 44 (3) ◽  
pp. 554-569 ◽  
Author(s):  
Elga Apsīte ◽  
Ilze Rudlapa ◽  
Inese Latkovska ◽  
Didzis Elferts
Keyword(s):  
River Runoff ◽  
River Discharge ◽  
Large Scale ◽  
Hydrological Regime ◽  
Turn Of The Century ◽  
Significant Trend ◽  
Low Flow ◽  
Data Series ◽  
Discharge Data ◽  
Baltic Countries

The study deals with turn-of-the-century changes in the total annual river runoff distribution and high and low flows in Latvia, covering river basins within four hydrological districts which vary according to size and physiographical conditions. Mathematical statistical methods were applied in the analysis of river discharge data series for two study periods of 1951–2009 and 1881–2009. The present results confirm the basic statement concerning the Baltic countries that major significant changes in river runoff during the last two decades have occurred between spring (decrease) and winter (increase) seasons. Mostly insignificant changes in summer runoff and significant/insignificant changes in autumn runoff were found. Analysis shows that a statistically significant trend of increase in low flow for the cold period and a significant trend of decrease in the high discharge and coefficient d of uneven runoff distribution were detected. Changes in river hydrological regime are mainly caused by changes in large-scale atmospheric circulation processes following climate warming, which has taken place. Latvian river hydrography has therefore changed and become more similar to Western European rivers.

scholarly journals Influence of ENSO and tropical Atlantic climate variability on flood characteristics in the Amazon basin

2020 ◽  
Author(s):  
Jamie Towner ◽  
Andrea Ficchí ◽  
Hannah L. Cloke ◽  
Juan Bazo ◽  
Erin Coughlan de Perez ◽  
...  
Keyword(s):  
Climate Variability ◽  
Early Warning ◽  
Large Scale ◽  
Amazon Basin ◽  
Early Warning Systems ◽  
Discharge Data ◽  
Flood Magnitude ◽  
Highly Correlated ◽  
The Impact ◽  
Flood Characteristics

Abstract. Flooding in the Amazon basin is frequently attributed to modes of large-scale climate variability, but little attention is paid to how these modes influence the timing and duration of floods despite their importance to early warning systems and the significant impacts that these flood characteristics can have on communities. In this study, river discharge data from the Global Flood Awareness System (GloFAS 2.1) and observed data at 58 gauging stations are used to examine whether positive/negative phases of several Pacific and Atlantic indices significantly alter the characteristics of river flows throughout the Amazon basin (1979–2015). Results show significant changes in both flood magnitude and duration, particularly in the north-eastern Amazon for negative ENSO years when the SST anomaly is positioned in the central tropical Pacific. This response is not identified for the eastern Pacific index, highlighting how the response can differ between ENSO types. Although flood magnitude and duration were found to be highly correlated, the impacts of large-scale climate variability on these characteristics are non-linear; some increases in annual flood maxima coincide with decreases in flood duration. The impact of flood timing however does not follow any notable pattern for all indices analysed. Finally, observed and simulated changes are found to be much more highly correlated for negative ENSO years compared to the positive phase, meaning that GloFAS struggles to accurately simulate the differences in flood characteristics between El Niño and neutral years. These results have important implications for both the social and physical sectors working towards the improvement of early warning action systems for floods.

scholarly journals The Mbam drainage system and onchocerciasis transmission post ivermectin mass drug administration (MDA) campaign, Cameroon

2021 ◽  
Vol 15 (1) ◽  
pp. e0008926
Author(s):  
Raphael Awah Abong ◽  
Glory Ngongeh Amambo ◽  
Ali Ahamat Hamid ◽  
Belinda Agbor Enow ◽  
Amuam Andrew Beng ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Large Scale ◽  
Water Discharge ◽  
Drainage System ◽  
River System ◽  
High Water ◽  
Diagnostic Techniques ◽  
Dry Seasons ◽  
The Impact

Background The impact of large scale Mass Drug Adminstration (MDA) of ivermectin on active onchocerciasis transmission by Simulium damnosum, which transmits the parasite O. volvulus is of great importance for onchocerciasis control programmes. We investigated in the Mbam river system area, the impact of MDA of ivermectin on entomological indices and also verify if there are river system factors that could have favoured the transmission of onchocerciasis in this area and contribute to the persistence of disease. We compared three independent techniques to detect Onchocerca larvae in blackflies and also analyzed the river system within 9 months post-MDA of ivermectin. Method Simulium flies were captured before and after 1, 3, 6 and 9months of ivermectin-MDA. The biting rate was determined and 41% of the flies dissected while the rest were grouped into pools of 100 flies for DNA extraction. The extracted DNA was then subjected to O-150 LAMP and real-time PCR for the detection of infection by Onchocerca species using pool screening. The river system was analysed and the water discharge compared between rainy and dry seasons. Principal findings We used human landing collection method (previously called human bait) to collect 22,274 adult female Simulium flies from Mbam River System. Of this number, 9,134 were dissected while 129 pools constituted for molecular screening. Overall biting and parous rates of 1113 flies/man/day and 24.7%, respectively, were observed. All diagnostic techniques detected similar rates of O. volvulus infection (P = 0.9252) and infectivity (P = 0.4825) at all monitoring time points. Onchocerca ochengi larvae were only detected in 2 of the 129 pools. Analysis of the river drainage revealed two hydroelectric dams constructed on the tributaries of the Mbam river were the key contributing factor to the high-water discharge during both rainy and dry seasons. Conclusion Results from fly dissection (Microscopy), real-time PCR and LAMP revealed the same trends pre- and post-MDA. The infection rate with animal Onchocerca sp was exceptionally low. The dense river system generate important breeding sites that govern the abundance of Simulium during both dry and rainy seasons.

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