Channel bed adjustment to over bankfull discharge magnitudes of the flysch gravel-bed stream – case study from the channelized reach of the Olše River (Czech Republic)

2016 ◽  
Vol 60 (4) ◽  
pp. 327-341 ◽  
Author(s):  
Václav Škarpich ◽  
Tomáš Galia ◽  
Jan Hradecký
Keyword(s):  
Land Use Changes ◽  
Stream Power ◽  
Cross Sectional ◽  
Average Width ◽  
Aerial Photos ◽  
Erosion Processes ◽  
Gravel Mining ◽  
Bankfull Discharge ◽  
River Bed ◽  
Flysch Carpathians

The rivers draining the Czech part of the Flysch Carpathians have deeply incised their beds over the last 60 years. This paper focuses on the Olše River in the Czech part of the Flysch Carpathians and summarises the results of the increased kinetic energy of flowing water of contemporary channel based on the analyse of hydraulic parameters of channel. The comparison of geodetic measurements from 1960 and 2003 was used together with the assessment of aerial photos from 1950s and present. The average width of the studied reach of the active Olše R. channel narrowed from 35 m in 1955 to 24 m in 2010. In some locations, the original river bed has lowered as much as 2.3 m between the years 1960 and 2003. Morphology of the Olše River channel has accelerated these erosion processes. The main reason for this is an adjustment of water flow dynamics. The unit stream power and hydraulic radius values have increased two to three times from 1960 to 2003 for 5, 20, 50 and 100-recurrence interval discharge. Incision of channel greater than 0.10–0.21m in the studied period may reflect change in cross-sectional geometry and lower than 0.10–0.21m may reflect other factors such as sediment disruption operating in the basin (e.g.with land-use changes, gravel mining etc.).

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 Spatial stochastic and analytical approaches to describe the complex hydraulic variability inherent channel geometry

2011 ◽  
Vol 8 (4) ◽  
pp. 6967-6992
Author(s):  
N. Hadadin
Keyword(s):  
Cross Sectional Area ◽  
Drainage Area ◽  
Channel Width ◽  
Hydraulic Geometry ◽  
Sectional Area ◽  
Stream Power ◽  
Cross Sectional ◽  
Bankfull Discharge ◽  
Yazoo River Basin ◽  
Runoff Production

Abstract. The effects of basin hydrology on channel hydraulic variability for incised streams were investigated using available field data sets and models of watershed hydrology and channel hydraulics for Yazoo River Basin, USA. The study presents the hydraulic relations of bankfull discharge, channel width, mean depth, cross- sectional area, longitudinal slope, unit stream power, and runoff production as a function of drainage area using simple linear regression. The hydraulic geometry relations were developed for sixty one streams, twenty of them are classified as channel evaluation model (CEM) Types IV and V and forty one of them are streams of CEM Types II and III. These relationships are invaluable to hydraulic and water resources engineers, hydrologists, and geomorphologists, involved in stream restoration and protection. These relations can be used to assist in field identification of bankfull stage and stream dimension in un-gauged watersheds as well as estimation of the comparative stability of a stream channel. Results of this research show good fit of hydraulic geometry relationships in the Yazoo River Basin. The relations indicate that bankfull discharge, channel width, mean depth, cross-sectional area have stronger correlation to changes in drainage area than the longitudinal slope, unit stream power, and runoff production for streams CEM Types II and III. The hydraulic geometry relations show that runoff production, bankfull discharge, cross-sectional area, and unit stream power are much more responsive to changes in drainage area than are channel width, mean depth, and slope for streams of CEM Types IV and V. Also, the relations show that bankfull discharge and cross-sectional area are more responsive to changes in drainage area than are other hydraulic variables for streams of CEM Types II and III. The greater the regression slope, the more responsive to changes in drainage area will be.

scholarly journals Consideration of land use in the evaluation of erosive processes in gully erosion

2020 ◽  
Vol 24 ◽  
pp. e25
Author(s):  
Tamara Vieira Pascoto ◽  
Simone Andrea Furegatti ◽  
Anna Silvia Palcheco Peixoto
Keyword(s):  
Land Use ◽  
Visual Analysis ◽  
Aerial Images ◽  
Aerial Photos ◽  
City Hall ◽  
Erosion Processes ◽  
Main Factors ◽  
The City ◽  
Erosive Feature

There are several factors that directly or indirectly influence erosion processes. In order to properly understand the behavior of these processes, some factors need to be analyzed together. Determining them wrongly can compromise the study resulting in wrong actions. For this reason, methodologies are always sought to measure them quantitatively and qualitatively in the most accurate possible way. Land use is one of the main factors liable to inaccuracies in its determination. To use this parameter in mapping erosive processes, researchers need to delimit it, classify it, and measure it. In order to better understand the complexity of considering this parameter, the present study analyzed an erosive feature that, although stabilized, has a component in constant development. Initially, a visual analysis indicated the same classification of land use for both conditions, despite having different behaviors, leading to the need for a detailed analysis. Such analysis comprised a historical survey through aerial photos and interviews with residents and employees of the city hall about the evolution of the feature from 2008 to 2019. It also included the analysis of other influencing factors that could be responsible for this difference in behavior in the area. Two different traces of the contribution areas of the gully and branch were also considered. One considering only aerial images, and the other considering the knowledge acquired during the research about the evolution of the feature. It was concluded, then, that an analysis of the use-only occupation factor based on aerial images can accentuate the inaccuracy of the measurement of this factor.

SEL VƏ DAŞQIN AXINLARINDA DAĞ ÇAYLARI MƏCRASININ YUYULMA DƏRİNLİYİNİN TƏYİNİ

2021 ◽  
Vol 1 (1) ◽  
pp. 82-88
Author(s):  
F.Ş., Əhmədov ◽  
R.K., Quliyev ◽  
R.Ü Əbdüləzimov
Keyword(s):  
Average Velocity ◽  
Average Diameter ◽  
Average Depth ◽  
Mountain River ◽  
Mountain Rivers ◽  
Cross Sectional ◽  
Average Width ◽  
Caucasus Mountains ◽  
Flood Flow

Abstract. The article is dedicated to the determination of the wash depth of mountain rivers in floods and overflows. As well-known, hydrotechnical equipment is exposed to destructive damages of the floods and overflows. The undersurface of bridge basement and coast guards are washed away, the surface of drainage devices in water supply and dams (Düker) at river crossings are opened up. Therefore, the protection of the equipment against the destructive damage of the floods and overflows should be ensured. To this aim, first of all, the depth of the fortification of the equipment basement in riverbeds and the width through which the river can flow should be determined and the works of installing coast guards should be accordingly implemented. Since the flow regime of rivers due to floods in the course of mountain riverbeds dramatically changes, the width, depth, roughness and cross-sectional area of the riverbed also changes. To that reason, in the smallest case, calculation formulas includes the average width and wash depth of the riverbed in the course of the floods and overflows, average diameter of undersurface soils, the slope of the location of hydrotechnical structures, velocity due to the average diameter of the riverbed soils and so on. The article contains the analyses of theoretical and practical materials about the floods and overflows in mountain rivers. For the rivers flowing through the southern hills of Great Caucasus Mountains, the expressions for determining the riverbed parameters and hydrological parameters of rivers are used. According to the expressions, average width due to non-washing of the riverbed in floods in accordance with flood flow and slope of the studied part of the riverbed, the average depth of the riverbed crossing the flood, the average velocity of the flow and the wash depth in accordance with them are determined. basing on all these, the determining method of the wash depth of mountain riverbeds in floods have been worked out and determining the wash depth have been recorded. The studied methodology can be used in determining the riverbed parameters in floods and overflows. Keywords: Flood, riverbed deformation, mountain river, wash depth, average diameter of undersurface sediments, riverbed stability, flood velocity

Prevention of Soil Erosion and Torrential Floods

2022 ◽  
pp. 92-111
Author(s):  
Bhavya Kavitha Dwarapureddi ◽  
Swathi Dash ◽  
Aman Raj ◽  
Nihanth Soury Garika ◽  
Ankit Kumar ◽  
...  
Keyword(s):  
Public Health ◽  
Climate Change ◽  
Soil Erosion ◽  
Erosion Rate ◽  
Land Use Changes ◽  
Climatic Conditions ◽  
Nutrient Loss ◽  
Erosion Processes ◽  
Over Exploitation ◽  
Flood Waves

Climatic conditions, precise relief features, variations of soil, flora cover, socio-economic conditions together lead to torrential flood waves as a result of current soil erosion processes. Erosion and torrential floods are aggravated due to over exploitation of agricultural and forest land along with urbanization. Effects of soil erosion include nutrient loss, land use changes, reduced productivity, siltation of water bodies, among other effects like affecting livelihood of marginal communities dependent on agriculture globally and public health. Nearly 11 million km2 of soil is impacted by erosion precisely by water. Other factors like intensified agriculture and climate change contribute to and aggravate the erosion rate. Contemporary torrential floods are characterized by their increased destruction and frequency unlike the pre-development periods when their occurrence was rare. The focus of this review is to compile and aid as a data base for understanding methods of preventing erosion of soil and torrential floods as put forth by various researchers.

scholarly journals Reconstructing long-term gully dynamics in Mediterranean agricultural areas

2017 ◽  
Vol 21 (1) ◽  
pp. 235-249 ◽  
Author(s):  
Antonio Hayas ◽  
Tom Vanwalleghem ◽  
Ana Laguna ◽  
Adolfo Peña ◽  
Juan V. Giráldez
Keyword(s):  
Land Use ◽  
Temporal Resolution ◽  
Land Use Changes ◽  
Mediterranean Area ◽  
Gully Erosion ◽  
Aerial Photographs ◽  
High Temporal Resolution ◽  
Erosion Rates ◽  
Erosion Processes

Abstract. Gully erosion is an important erosive process in Mediterranean basins. However, the long-term dynamics of gully networks and the variations in sediment production in gullies are not well known. Available studies are often conducted only over a few years, while many gully networks form, grow, and change in response to environmental and land use or management changes over a long period. In order to clarify the effect of these changes, it is important to analyse the evolution of the gully network with a high temporal resolution. This study aims at analysing gully morphodynamics over a long timescale (1956–2013) in a large Mediterranean area in order to quantify gully erosion processes and their contribution to overall sediment dynamics. A gully network of 20 km2 located in southwestern Spain has been analysed using a sequence of 10 aerial photographs in the period 1956–2013. The extension of the gully network both increased and decreased in the study period. Gully drainage density varied between 1.93 km km−2 in 1956, a minimum of 1.37 km km−2 in 1980, and a maximum of 5.40 km km−2 in 2013. The main controlling factor of gully activity appeared to be rainfall. Land use changes were found to have only a secondary effect. A new Monte Carlo-based approach was proposed to reconstruct gully erosion rates from orthophotos. Gully erosion rates were found to be relatively stable between 1956 and 2009, with a mean value of 11.2 t ha−1 yr−1. In the period 2009–2011, characterized by severe winter rainfalls, this value increased significantly to 591 t ha−1 yr−1. These results show that gully erosion rates are highly variable and that a simple interpolation between the starting and ending dates greatly underestimates gully contribution during certain years, such as, for example, between 2009 and 2011. This illustrates the importance of the methodology applied using a high temporal resolution of orthophotos.

scholarly journals Classifying low flow hydrological regimes at a regional scale

2011 ◽  
Vol 15 (12) ◽  
pp. 3741-3750 ◽  
Author(s):  
M. J. Kirkby ◽  
F. Gallart ◽  
T. R. Kjeldsen ◽  
B. J. Irvine ◽  
J. Froebrich ◽  
...  
Keyword(s):  
Regional Scale ◽  
Low Flow ◽  
Balance Model ◽  
Hydraulic Geometry ◽  
Climate Data ◽  
Cross Sectional ◽  
Flow Duration ◽  
River Bed ◽  
Climatic Scenarios ◽  
Flow Duration Curves

Abstract. The paper uses a simple water balance model that partitions the precipitation between actual evapotranspiration, quick flow and delayed flow, and has sufficient complexity to capture the essence of climate and vegetation controls on this partitioning. Using this model, monthly flow duration curves have been constructed from climate data across Europe to address the relative frequency of ecologically critical low flow stages in semi-arid rivers, when flow commonly persists only in disconnected pools in the river bed. The hydrological model is based on a dynamic partitioning of precipitation to estimate water available for evapotranspiration and plant growth and for residual runoff. The duration curve for monthly flows has then been analysed to give an estimate of bankfull flow based on recurrence interval. Arguing from observed ratios of cross-sectional areas at flood and low flows, hydraulic geometry suggests that disconnected flow under "pool" conditions is approximately 0.1% of bankfull flow. Flow duration curves define a measure of bankfull discharge on the basis of frequency. The corresponding frequency for pools is then read from the duration curve, using this (0.1%) ratio to estimate pool discharge from bank full discharge. The flow duration curve then provides an estimate of the frequency of poorly connected pool conditions, corresponding to this discharge, that constrain survival of river-dwelling arthropods and fish. The methodology has here been applied across Europe at 15 km resolution, and the potential is demonstrated for applying the methodology under alternative climatic scenarios.

scholarly journals The Importance of Environmental Factors for the Development of Water Erosion of Soil in Agricultural Land: The Southern Part of Hronská Pahorkatina Hill Land, Slovakia

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1234
Author(s):  
Viera Petlušová ◽  
Peter Petluš ◽  
Michal Ševčík ◽  
Juraj Hreško
Keyword(s):  
Land Use ◽  
Environmental Factors ◽  
Geographical Information Systems ◽  
Agricultural Land ◽  
Land Use Changes ◽  
Water Erosion ◽  
Geographical Information ◽  
Aerial Photographs ◽  
Slope Length ◽  
Erosion Processes

The water erosion research was carried out in the lowland type of hilly landscape. The aim was to monitor and evaluate the importance of environmental factors (steepness of slope, relief shapes, aspect, slope length, combination slope length (L) and slope (S)—LS factor, types of land use changes) for the development of water erosion. We focused on the identification of areas threatened by erosion by interpreting aerial photographs from several time periods. This was followed by verification of erosion using soil probes. We identified 408.44 ha of areas affected by erosion, and measured the depth of soil and “A” horizons thickness. The environmental factors were modeled in geographical information systems by tools for spatially oriented data. Subsequently, the influence and significance of individual environmental factors were compared, and the probability of erosion was statistically estimated. The decisive factors in the formation of erosive surfaces are the LS factor and the slope. We also consider the factor of the relief shape to be important. The shape did not appear to be very significant as a separately evaluated factor, but all convex parts correlate with the identified erosion surfaces. The susceptibility of erosion related to the aspect of the slopes to the cardinal directions has not been confirmed. Types of land use changes with the most significant relation of erosion were confirmed in areas of strong intensification. We confirmed the importance of factors and land use for the development of erosion processes.

Sedimentation in the Reservoir of the Altenwoerth Hydropower Plant

1990 ◽  
Vol 22 (5) ◽  
pp. 173-180
Author(s):  
H. P. Nachtnebel ◽  
W. Summer ◽  
H. Mueller ◽  
B. Schwaighofer
Keyword(s):  
Heavy Metal ◽  
Grain Size ◽  
Longitudinal Section ◽  
Hydropower Plant ◽  
Sediment Layer ◽  
Stream Power ◽  
Metal Concentrations ◽  
Heavy Metal Concentrations ◽  
Sludge Disposal ◽  
River Bed

This paper addresses two objectives. The first objective is to describe the sedimentation process in the reservoir of the hydropower scheme Altenwoerth. It is located on the Austrian part of the Danube about 60 km upstream from Vienna. Starting in 1976 the aggradation of the river bed has been monitored annually to estimate the sedimentation rate along a longitudinal section in the reservoir. Further, cores were taken over the whole sediment layer to analyse the grain size distribution, the bulk density, the mineralogic structure of the sediment and the heavy metal concentrations in the layer. It was found that the annual average sedimentation of suspended material amounts to 390 000 m3/a. The grain size of the samples vary from well sorted sands to poorly sorted, clay rich sediments. The heavy metal concentrations refer to the fraction less than 20 µ m. In comparison to the guidelines for sewage sludge disposal the observed heavy metal content of zn and Pb is slightly above the respective limits. The second objective is to demonstrate the application of a one dimensional sedimentation model which describes the accumulation over the operation period from 1976 to 1985. The model is related to the unit stream power concept and is based on the transport capacity equation of Engelund and Hansen. The model yields satisfying results for both the quantity of the sediment and also its gradation.

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