scholarly journals Geomorphic Effects of Flooding Along Reaches of Selected Rivers in the Saguenay Region, Québec, July 1996

2002 ◽  
Vol 54 (3) ◽  
pp. 281-299 ◽  
Author(s):  
G. R. Brooks ◽  
D. E. Lawrence
Keyword(s):  
Empirical Evidence ◽  
Unconsolidated Sediments ◽  
Stream Power ◽  
Flow Energy ◽  
Extreme Flood ◽  
Channel Widening ◽  
Flood Flow

AbstractA severe rainstorm from July 18 to 21, 1996, caused widespread flooding along many rivers in southern Québec, particularly in the Lac-Saint-Jean-Chicoutimi area, along north-flowing tributaries of the Rivière Saguenay. Along study reaches located on the Rivière aux Sables, Rivière Chicoutimi, Rivière du Moulin and Rivière à Mars, the fluvial geomorphic effects of flooding varied considerably, reflecting differing channel morphologies (alluvial, non-alluvial and bedrock), flow energy, and the interaction of floodwaters and infrastructure. Catastrophic channel widening and floodplain reworking occurred along the Rivière à Mars study reach, transforming the river from a meandering to braided planform. Consistent with this, unit stream power of the flood flow exceeded the minimum erosive threshold (300 Wm-2) along most of the study reach. Morphological and empirical evidence indicates that the pre-flood Rivière à Mars channel exhibited a transitional planform, and thus was vulnerable to a planform transformation during an extreme flood. The most significant geomorphic effects along the Rivière aux Sables and Rivière Chicoutimi study reaches occurred at a number of run-of-the-river dams. Floodwaters overtopped four dams and eroded deeply into unconsolidated sediments adjacent to the dams, forming new channels that captured the flow of the river. Floodwaters also overtopped a fifth dam, scouring overburden and road beds, and damaging and destroying buildings within an urban subdivision. Elsewhere along these two rivers, as well as along the Rivière du Moulin study reach, there were localized erosional problems, particularly at bridges, but the geomorphic effects generally were limited or negligible, reflecting either low unit stream power or resistant substrates.

scholarly journals Scale orientated analysis of river width changes due to extreme flood hazards

2011 ◽  
Vol 11 (8) ◽  
pp. 2137-2147 ◽  
Author(s):  
G. Krapesch ◽  
C. Hauer ◽  
H. Habersack
Keyword(s):  
Numerical Models ◽  
Width Ratio ◽  
Flood Hazards ◽  
Stream Power ◽  
Flow Area ◽  
Cross Sectional ◽  
Average Width ◽  
Extreme Floods ◽  
Mean Width ◽  
Extreme Flood

Abstract. This paper analyses the morphological effects of extreme floods (recurrence interval >100 years) and examines which parameters best describe the width changes due to erosion based on 5 affected alpine gravel bed rivers in Austria. The research was based on vertical aerial photos of the rivers before and after extreme floods, hydrodynamic numerical models and cross sectional measurements supported by LiDAR data of the rivers. Average width ratios (width after/before the flood) were calculated and correlated with different hydraulic parameters (specific stream power, shear stress, flow area, specific discharge). Depending on the geomorphological boundary conditions of the different rivers, a mean width ratio between 1.12 (Lech River) and 3.45 (Trisanna River) was determined on the reach scale. The specific stream power (SSP) best predicted the mean width ratios of the rivers especially on the reach scale and sub reach scale. On the local scale more parameters have to be considered to define the "minimum morphological spatial demand of rivers", which is a crucial parameter for addressing and managing flood hazards and should be used in hazard zone plans and spatial planning.

River flow hydrograph simulation in the Western Siberia lowland north for the extreme flood flow prediction based on the HBV-Light model

2020 ◽  
pp. 98-107
Author(s):  
Sergey G. Kopysov ◽  
◽  
Valerii A. Zemtsov ◽  
Hiroshi Matsuyama ◽  
Artem O. Eliseev
Keyword(s):  
Western Siberia ◽  
River Flow ◽  
Flow Prediction ◽  
Extreme Flood ◽  
Flood Flow

scholarly journals Impacts of a large flood along a mountain river basin: the importance of channel widening and estimating the large wood budget in the upper Emme River (Switzerland)

2018 ◽  
Vol 6 (4) ◽  
pp. 1115-1137 ◽  
Author(s):  
Virginia Ruiz-Villanueva ◽  
Alexandre Badoux ◽  
Dieter Rickenmann ◽  
Martin Böckli ◽  
Salome Schläfli ◽  
...  
Keyword(s):  
River Basin ◽  
Large Scale ◽  
Management Strategies ◽  
Bank Erosion ◽  
River Basin Management ◽  
Channel Width ◽  
Large Wood ◽  
Stream Power ◽  
Channel Widening ◽  
Overbank Sedimentation

Abstract. On 24 July 2014, an exceptionally large flood (recurrence interval ca. 150 years) caused large-scale inundations, severe overbank sedimentation, and damage to infrastructure and buildings along the Emme River (central Switzerland). Widespread lateral bank erosion occurred along the river, thereby entraining sediment and large wood (LW) from alluvial forest stands. This work analyzes the catchment response to the flood in terms of channel widening and LW recruitment and deposition, but also identifies the factors controlling these processes. We found that hydraulic forces (e.g., stream power index) or geomorphic variables (e.g., channel width, gradient, valley confinement), if considered alone, are not sufficient to explain the flood response. Instead, the spatial variability of channel widening was first driven by precipitation and secondly by geomorphic variables (e.g., channel width, gradient, confinement, and forest length). LW recruitment was mainly caused by channel widening (lateral bank erosion) and thus indirectly driven by precipitation. In contrast, LW deposition was controlled by channel morphology (mainly channel gradient and width). However, we also observed that extending the analysis to the whole upper catchment of the Emme River by including all the tributaries and not only to the most affected zones resulted in a different set of significant explanatory or correlated variables. Our findings highlight the need to continue documenting and analyzing channel widening after floods at different locations and scales for a better process understanding. The identification of controlling factors can also contribute to the identification of critical reaches, which in turn is crucial for the forecasting and design of sound river basin management strategies.

scholarly journals Impacts of a large flood along a mountain river basin: unravelling the geomorphic response and large wood budget in the upper Emme River (Switzerland)

2018 ◽  
Author(s):  
Virginia Ruiz-Villanueva ◽  
Alexandre Badoux ◽  
Dieter Rickenmann ◽  
Martin Böckli ◽  
Salome Schläfli ◽  
...  
Keyword(s):  
River Basin ◽  
Large Scale ◽  
Management Strategies ◽  
Bank Erosion ◽  
River Basin Management ◽  
Channel Width ◽  
Large Wood ◽  
Stream Power ◽  
Channel Widening ◽  
Overbank Sedimentation

Abstract. On July 24, 2014, an exceptionally large flood (recurrence interval ca. 150 years) caused large-scale inundations, severe overbank sedimentation and damage to infrastructures and buildings along the Emme river (central Switzerland). Widespread lateral bank erosion occurred along the river, thereby entraining sediment and large wood (LW) from alluvial forest stands. This work analyses the catchment response to the flood in terms of channel widening and LW recruitment and deposition, but also identifies the factors controlling these processes. We found that hydraulic forces (e.g., stream power index) or geomorphic variables (e.g., channel width, gradient, valley confinement), if considered alone, are not sufficient to explain the flood response. Instead, spatial variability of channel widening was firstly driven by precipitation, and secondary by geomorphic variables (e.g., channel width, gradient, confinement and forest length). LW recruitment was mainly caused by channel widening (lateral bank erosion) and thus also controlled by precipitation. In contrast, LW deposition was controlled by channel morphology (mainly channel gradient and width). However, we also observed that extending the analysis to the whole upper catchment of the Emme river, including all the tributaries and not only to the most affected zones, resulted in a different set of significant explanatory or correlated variables. Our findings highlight the need to continue documenting and analysing channel response after floods at different locations and scales. Whereas this is key for a better process understanding, the identification of controlling factors can also contribute to the identification of critical reaches, which in turn is crucial for the forecasting and design of sound river basin management strategies.

scholarly journals Short-Term GIS Analysis for the Assessment of the Recent Active-Channel Planform Adjustments in a Widening, Highly Altered River: The Scrivia River, Italy

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 514 ◽  
Author(s):  
Andrea Mandarino ◽  
Giacomo Pepe ◽  
Michael Maerker ◽  
Andrea Cevasco ◽  
Pierluigi Brandolini
Keyword(s):  
Aerial Photographs ◽  
Stream Power ◽  
Mean Width ◽  
Triggering Factor ◽  
Recent Phase ◽  
Channel Widening ◽  
Gis Environment ◽  
Nw Italy ◽  
Active Channel ◽  
Channel Planform

From the 1990s onwards several Italian rivers have experienced a recent phase characterized by active-channel widening and, generally, by bed-level stability or slight aggradation. However, its triggering factors and its diffusion, along with the relationship between active-channel planform dynamics and vertical adjustments, are still quite debated and only few studies are available. This research deals with the active-channel planform changes occurred along the Scrivia River floodplain reach (NW Italy) over the period 1999–2019 and it aims at investigating in detail the ongoing geomorphological processes under the river management perspective. The study is based on a quantitative multitemporal analysis of aerial photographs and satellite images performed in a GIS environment and supported by field surveys. The outcomes revealed a generalized trend of gentle active-channel widening together with widespread bank instability and several (26% of total banks) intense and localized bank retreats involving both the modern floodplain and the recent terrace. In the investigated 20-year period, the active-channel area has increased by 22.7% (from 613.6 to 753.0 ha), its mean width by 25% (from 151.5 to 189.3 m), whereas no relevant length variations have been noticed. These morphological dynamics have been more or less pronounced both at reach scale and over time. The extreme floods occurred in the investigated period can be considered the most important triggering factor of the active-channel planform changes, most probably together with an increase of the reach-scale unit stream power due to changes in the channel geometry occurred over the 20th century.

How do rural-urban linkages change after an extreme flood event? Empirical evidence from rural communities in Pakistan

2021 ◽  
Vol 750 ◽  
pp. 141462
Author(s):  
Ali Jamshed ◽  
Joern Birkmann ◽  
Joanna M. McMillan ◽  
Irfan Ahmad Rana ◽  
Daniel Feldmeyer ◽  
...  
Keyword(s):  
Rural Communities ◽  
Empirical Evidence ◽  
Flood Event ◽  
Extreme Flood

scholarly journals Optimized Vegetation Density to Dissipate Energy of Flood Flow in Open Canals

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Mahdi Feizbahr ◽  
Navid Tonekaboni ◽  
Guang-Jun Jiang ◽  
Hong-Xia Chen
Keyword(s):  
Flow Velocity ◽  
Cross Section ◽  
Flow Resistance ◽  
Vegetation Density ◽  
Flow Conditions ◽  
Average Flow ◽  
Flow Energy ◽  
Average Flow Velocity ◽  
Flow Velocity Profile ◽  
Flood Flow

Vegetation along the river increases the roughness and reduces the average flow velocity, reduces flow energy, and changes the flow velocity profile in the cross section of the river. Many canals and rivers in nature are covered with vegetation during the floods. Canal’s roughness is strongly affected by plants and therefore it has a great effect on flow resistance during flood. Roughness resistance against the flow due to the plants depends on the flow conditions and plant, so the model should simulate the current velocity by considering the effects of velocity, depth of flow, and type of vegetation along the canal. Total of 48 models have been simulated to investigate the effect of roughness in the canal. The results indicated that, by enhancing the velocity, the effect of vegetation in decreasing the bed velocity is negligible, while when the current has lower speed, the effect of vegetation on decreasing the bed velocity is obviously considerable.

Challenges to the social motivation theory of autism: The dangers of counteracting an imprecise theory with even more imprecision

2019 ◽  
Vol 42 ◽  
Author(s):  
Mirko Uljarević ◽  
Giacomo Vivanti ◽  
Susan R. Leekam ◽  
Antonio Y. Hardan
Keyword(s):  
Empirical Evidence ◽  
Social Motivation ◽  
Motivation Theory ◽  
The Social

Abstract The arguments offered by Jaswal & Akhtar to counter the social motivation theory (SMT) do not appear to be directly related to the SMT tenets and predictions, seem to not be empirically testable, and are inconsistent with empirical evidence. To evaluate the merits and shortcomings of the SMT and identify scientifically testable alternatives, advances are needed on the conceptualization and operationalization of social motivation across diagnostic boundaries.

Integrating perspectives: How the development of second-personal competence lays the foundation for a second-personal morality

2020 ◽  
Vol 43 ◽  
Author(s):  
John Corbit ◽  
Chris Moore
Keyword(s):  
Empirical Evidence ◽  
Developmental Process ◽  
Focal Point ◽  
Personal Information ◽  
Personal Competence ◽  
Triadic Interactions ◽  
Personal Morality ◽  
Integrative Process

Abstract The integration of first-, second-, and third-personal information within joint intentional collaboration provides the foundation for broad-based second-personal morality. We offer two additions to this framework: a description of the developmental process through which second-personal competence emerges from early triadic interactions, and empirical evidence that collaboration with a concrete goal may provide an essential focal point for this integrative process.

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