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.

scholarly journals Intrinsic Environmental Vulnerability as Shallow Landslide Susceptibility in Environmental Impact Assessment

2019 ◽  
Vol 11 (22) ◽  
pp. 6285 ◽  
Author(s):  
Laura Turconi ◽  
Fabio Luino ◽  
Mattia Gussoni ◽  
Francesco Faccini ◽  
Marco Giardino ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Impact Assessment ◽  
Environmental Impact Assessment ◽  
Landslide Susceptibility ◽  
Shallow Landslide ◽  
Environmental Vulnerability ◽  
Shared Information ◽  
Gis Environment ◽  
Nw Italy ◽  
Policy And Planning

This work investigated the susceptibility factors that trigger shallow landslides. In particular, the objective of the research was the implementation of a method to determine the relevant factors that can trigger shallow landslide events. However, with respect to the existing methods, the integration with historical datasets and the inclusion of spatial factors displaying dynamics in the same characteristic timescales were specific features of the developed tool. The study area included the watersheds of the Sessera and Strona rivers in the alpine area of the Province of Biella (Piedmont, NW Italy). The method was developed and tested from two sub-datasets derived from an integrated dataset that referred to an intense event, involving the same area, that occurred in 1968 (2–3 November). This allowed the implementation of an integrated representation of landslides’ predisposing factors and the identification and classification in different groups of the areas susceptible to geo-hydrological instability processes. The previously existing databases were verified and integrated into a geographic information system (GIS) environment, giving a potentially sharable source of information for planning purposes. The obtained maps represent a metric of one of the possible intrinsic environmental vulnerability factors for the area under study. Consequently, this method can represent a future instrument for determining the intrinsic environmental vulnerability dependent on landslides within an environmental impact assessment (EIA), as required by the most recent European regulation on EIA. Moreover, the shared information can be used to implement informed policy and planning processes, based on a bottom-up approach. In particular, the availability online of landslide susceptibility maps could support the generation of augmented information—useful for both local administrators and planners as well as for stakeholders willing to implement specific projects or infrastructure in vulnerable areas, such as mountains.

Gravel replenishment and active-channel widening for braided-river restoration: The case of the Upper Drac River (France)

2020 ◽  
pp. 142517
Author(s):  
Guillaume Brousse ◽  
Frédéric Liébault ◽  
Gilles Arnaud-Fassetta ◽  
Bertrand Breilh ◽  
Sandrine Tacon
Keyword(s):  
River Restoration ◽  
Braided River ◽  
Channel Widening ◽  
Active Channel

scholarly journals Stream Power Determination in GIS: An Index to Evaluate the Most ’Sensitive’Points of a River

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1145 ◽  
Author(s):  
Pierluigi De Rosa ◽  
Andrea Fredduzzi ◽  
Corrado Cencetti
Keyword(s):  
Methodological Approach ◽  
Main Stream ◽  
Stream Power ◽  
Digital Elevation ◽  
Original Definition ◽  
Study Support ◽  
Solid Transport ◽  
Gis Environment ◽  
Standardized Screening ◽  
Hydrographic Network

This paper focuses on the problem of measuring stream power in a hydrographic network using the original definition provided by Bagnold in 1996. Recent digital elevation models have enabled the calculation of channel gradients and, consequently, stream power with a finer spatial resolution, and this has created promising and novel opportunities to investigate river geomorphological processes and forms. The work carried out in this study includes defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: (1) it uses a DEM as input data at a suitable resolution; (2) it estimates the stream power Ω , as well as its variability along the considered stream, in the best possible way using available data. In particular, the methodological approach was implemented in a GIS environment (GRASS GIS) and applied to a sample basin to highlight the variability in Ω along the main stream and its most important tributaries. The sudden and more substantial variations in stream power were then related to the processes acting in the fluvial system. This approach made it possible to highlight how erosion, solid transport, and sedimentation phenomena occurring along the fluvial reaches are related to abrupt variations (increase/decrease) in the “power” available. The results of this study support the idea that the automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most “sensitive” points of the stream on which to concentrate subsequent investigations (field checks to verify the causes), with the aim of mitigating risks due to the dynamics of the riverbed.

scholarly journals The stream power variation in a GIS environment as an index to evaluate the most 'sensitive' points of a river

2018 ◽  
Author(s):  
Pierluigi De Rosa ◽  
Corrado Cencetti ◽  
Andrea Fredduzzi
Keyword(s):  
Methodological Approach ◽  
Specific Weight ◽  
Main Stream ◽  
Stream Power ◽  
Time Rate ◽  
Liquid Discharge ◽  
Digital Elevation ◽  
Original Definition ◽  
Solid Transport ◽  
Gis Environment

The note deals with the problem of measurement and variability, along the fluvial reaches of a hydrographic network, of the stream power, according to the original definition provided by Bagnold (1966) “The available power supply, or time rate of energy supply, to unit lenght of a stream is clearly the time rate of liberation in kinetic form of the liquid’s potential energy as it descends the gravity slope S”. In formula: Ω = ρ g Q S where: Ω = stream power per unit of flow length (W/m) ρ g = density x gravity acceleration = specific weight of the fluid (kg/m3) Q = liquid discharge (m3/s) S = slope of the considered reach (m/m). Recent digital elevation models allow the calculation of channel gradient and consequently stream power with a finer spatial resolution, opening promising and novel opportunities to investigate river geomorphical processes and forms. The work carried out consisted in defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: 1) use input data that is easy to find as DEM at a low resolution; 2) estimate, in the best possible way and on the basis of the available data, the stream power and its variability along the considered stream. In particular, the methodological approach has been implemented in GIS environment (GRASS Gis, Qgis), and it has been applied to a sample basin, highlighting the variability of Ω along the streams of a higher order (in practice the main stream and its most important tributaries). The sudden and more substantial variations of stream power were then related to the processes acting in the fluvial system. This approach has made it possible to highlight how the erosion, solid transport and sedimentation phenomena occurring along the fluvial reaches (and the geomorphological and geologicalapplicative problems that these involve, especially in anthropized areas), are correlated precisely to abrupt variations (increase/decrease) of the ”power” available. Hence the idea that automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most ”sensitive” points of the same, on which to concentrate subsequent investigations (field checks, to verify the causes), aimed at mitigating the risk due to the dynamics of the riverbed.

scholarly journals The stream power variation in a GIS environment as an index to evaluate the most 'sensitive' points of a river

2018 ◽  
Author(s):  
Pierluigi De Rosa ◽  
Corrado Cencetti ◽  
Andrea Fredduzzi
Keyword(s):  
Methodological Approach ◽  
Specific Weight ◽  
Main Stream ◽  
Stream Power ◽  
Time Rate ◽  
Liquid Discharge ◽  
Digital Elevation ◽  
Original Definition ◽  
Solid Transport ◽  
Gis Environment

The note deals with the problem of measurement and variability, along the fluvial reaches of a hydrographic network, of the stream power, according to the original definition provided by Bagnold (1966) “The available power supply, or time rate of energy supply, to unit lenght of a stream is clearly the time rate of liberation in kinetic form of the liquid’s potential energy as it descends the gravity slope S”. In formula: Ω = ρ g Q S where: Ω = stream power per unit of flow length (W/m) ρ g = density x gravity acceleration = specific weight of the fluid (kg/m3) Q = liquid discharge (m3/s) S = slope of the considered reach (m/m). Recent digital elevation models allow the calculation of channel gradient and consequently stream power with a finer spatial resolution, opening promising and novel opportunities to investigate river geomorphical processes and forms. The work carried out consisted in defining and implementing a methodological approach that could be automated within a geographic information system and that meets two requirements: 1) use input data that is easy to find as DEM at a low resolution; 2) estimate, in the best possible way and on the basis of the available data, the stream power and its variability along the considered stream. In particular, the methodological approach has been implemented in GIS environment (GRASS Gis, Qgis), and it has been applied to a sample basin, highlighting the variability of Ω along the streams of a higher order (in practice the main stream and its most important tributaries). The sudden and more substantial variations of stream power were then related to the processes acting in the fluvial system. This approach has made it possible to highlight how the erosion, solid transport and sedimentation phenomena occurring along the fluvial reaches (and the geomorphological and geologicalapplicative problems that these involve, especially in anthropized areas), are correlated precisely to abrupt variations (increase/decrease) of the ”power” available. Hence the idea that automated and standardized screening of stream power variability along a stream can be used as a preliminary diagnostic element to identify the most ”sensitive” points of the same, on which to concentrate subsequent investigations (field checks, to verify the causes), aimed at mitigating the risk due to the dynamics of the riverbed.

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 Impact of Anthropogenic Facilities on the Morphodynamic Evolution of an Estuarine System: The Case of Oum Er-Rbia Estuary (Azemmour, Morocco)

2019 ◽  
Vol 7 (8) ◽  
pp. 248 ◽  
Author(s):  
Mustapha El Jakani ◽  
Said Ettazarini ◽  
Hassan Rhinane ◽  
Mohammed Raji ◽  
Mohamed Radid ◽  
...  
Keyword(s):  
River Flow ◽  
Field Work ◽  
Google Earth ◽  
Aerial Photographs ◽  
Estuarine System ◽  
Watershed Area ◽  
Morphologic Evolution ◽  
Gis Environment ◽  
Morphodynamic Evolution ◽  
Sand Deposition

The Oum Er-Rbia estuary is located on the Atlantic littoral of Morocco. It undergoes severe clogging due to the sand deposition in its outlet. The current study examined the indicators of the morphodynamic evolution in the littoral system including the Oum Er-Rbia estuary and the neighboring beaches over 1970–2017. The methodology adopted was based on the analysis and the interpretation of aerial photographs and Google Earth images under a GIS environment and field work. The morphodynamic evolution was discussed by taking into account the evolution of hydraulic facilities installed in the watershed area, especially the construction of dams, as well as the dredging works in the Oum Er-Rbia estuary. The results highlight the morphologic evolution estimated in terms of surface units observed in the estuary and the neighboring beaches. The evolution of the littoral system was mainly influenced by the closest dam location and by the dredging works, in addition to the regulation of the river flow by the installation of hydraulic facilities upstream.

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.

scholarly journals Application of GIS Technologies and Aerial Photography for Geoinformation Mapping and Modelling of Relief of Agroland Landscapes

2020 ◽  
Vol 34 ◽  
pp. 82-95
Author(s):  
S. V. Pashkov ◽  
◽  
G. Z. Mazhitova ◽  
Keyword(s):  
Precision Agriculture ◽  
Aerial Photography ◽  
Crop Production ◽  
Large Scale ◽  
Local Level ◽  
Field Studies ◽  
Aerial Photographs ◽  
Visible Range ◽  
Gis Technologies ◽  
Gis Environment

The article is devoted to one of the topical applied areas of agrarian landscape research – geoinformation mapping, the development of maps and models of the topography of agricultural areas. The authors demonstrate results of works on large-scale geoinformation mapping and modeling of the topography of the oldest region of bogharic agriculture of Kazakhstan – North Kazakhstan region using methods and materials of remote sensing data and GIS technologies. The main source material in the study was a series of aerial photographs obtained from an unmanned aerial vehicle (UAV). The site of photographing was carried out by GEOSCAN-Kazakhstan LLP with using the Geoscan-201M Agro/Geodesy aerial photography complex. Characteristics of photographing: height – 280 m, visible range – 5 cm/pixel, multispectral – 13 cm/pixel. Geoinformation data on the nature of the relief were obtained during field studies in 2018-2020. Studies were carried out at the local level on the example of agricultural area located in the north of the region within the forest and steppe arable small-circuit agrarian landscape. Based on the results of the study, an electronic vector basis and specialized attribute data of the key area in the GIS environment, a digital relief model were prepared, spatial analysis and modeling of the geomorphological device of the arable surface were performed. The importance of the work is given by a significant agrogenic transformation of the relief of the definite locality during the almost 270-year history of agriculture. A series of maps of the main characteristics and morphometric indicators of the relief, significant from the point of view of crop production intensification and the development of accurate (precision) agriculture of the region, has been worked out. As a result of the study, the methodology of large-scale geoinformation mapping and modeling of the terrain of agrolandscapes in the GIS environment based on aerial photographs from UAVs was developed and tested. The algorithm of work has been compiled, starting from field studies, completing with the development of thematic maps and morphometric analysis of the relief and nature of the surface structure of the studied area.

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.

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