Bed Degradation – Nature, Causes, Countermeasures

1994 ◽  
Vol 29 (3) ◽  
pp. 325-333 ◽  
Author(s):  
E. Gölz
Keyword(s):  
Flood Plain ◽  
Bed Load ◽  
River Rhine ◽  
River Engineering ◽  
Morphological Process ◽  
River Bed ◽  
Degradation Rates ◽  
River Training ◽  
Abandoned Channels ◽  
Lower Rhine

Bed degradation is the dominant morphological process along the freely flowing river Rhine between Iffezheim and the German-Dutch border with degradation rates varying between 5 and 50 mm year1. As a continuing bed degradation may cause severe economical and ecological damage, nature, causes and extent of degradation have been studied using two diving bell watercraft. Additional petrographic examinations of bed sediments as well as bed load measurements have revealed that bed degradation of the Lower Rhine is mainly caused by bed load deficits due to the specific morphotectonic conditions as well as anthropogenic interference, especially impounding of the big tributaries. Low degradation rates are a precondition for certain rehabilitation measures as, e.g. restoring of flood plain areas and reactivation of abandoned channels and meander belts. Therefore stabilisation of the river bed is an important task for ecological river engineering. For the river Rhine a stabilisation strategy is suggested combining conventional river training works, maintenance measures and artificial bed load supply.

Gravel-Pit Lakes Connected with the River Rhine as a Reserve for High Productivity of Plankton and Young Fish

1994 ◽  
Vol 29 (3) ◽  
pp. 267-271 ◽  
Author(s):  
D. Neumann ◽  
Chr Seidenberg-Busse ◽  
A. Petermeier ◽  
St Staas ◽  
F. Molls ◽  
...  
Keyword(s):  
Flood Plain ◽  
River Rhine ◽  
Flood Events ◽  
Eutrophic Lakes ◽  
Field Station ◽  
High Productivity ◽  
Sand And Gravel ◽  
The University ◽  
Lentic Waters ◽  
Lower Rhine

During the last two decades an increasing number of sand and gravel-pits were established in the original flood plain of the River Rhine. Some of these are connected with the stream by a small canal for the transport of the spoil. Some of these dredged lakes have been studied during recent years at the ecological field station of the University of Köln, with regard to seasonal phytoplankton succession, productivity of copepods and cladocerans, occurrence of macrozoobenthos, and both spawning and recruitment of fish populations. These eutrophic lakes represent a valuable substitute biotope for lost lentic waters of the former flood plain. They offer via the canal connection an advantageous habitat to resident fish species of the Lower Rhine, (1) for reproduction and growth of the 0+-generation, and (2) for shelter during flood events. Recommendations for reclamation plans of such lakes are required.

scholarly journals METHODOLOGY FOR HYDRAULIC CALCULATION OF RIVER REGULATION AND DETERMINATION OF DIKE PARAMETERS

2017 ◽  
Vol 16 (4) ◽  
pp. 298-303
Author(s):  
E. I. Mikhnevich
Keyword(s):  
Water Level ◽  
Water Flow Rate ◽  
Flood Plain ◽  
River Regulation ◽  
Hydraulic Calculation ◽  
Design Parameters ◽  
Flood Water ◽  
River Bed ◽  
Belt Width

Territory protection against flood water inundation and creation of polder systems are carried out with the help of protection dikes. One of the main requirements to the composition of polder systems in flood plains is a location of border dikes beyond meander belt in order to avoid their erosion when meander development occurs. Meander belt width can be determined on the basis of the analysis of multi-year land surveying pertaining top river-bed building and in the case when such data is not available this parameter is calculated in accordance with the Snishchenko formula. While banking-up a river bed a flooded area is decreasing and, consequently, water level in inter-dike space and rate of flood water are significantly increasing. For this reason it is necessary to locate dikes at a such distance from a river bed which will not cause rather high increase in water level and flow velocity in the inter-dike space. Methodology for hydraulic calculation of river regulation has been developed in order to substantiate design parameters for levee systems, creation of favourable hydraulic regime in these systems and provision of sustainability for dikes. Its main elements are calculations of pass-through capacity of the leveed channel and rise of water level in inter-dike space, and distance between dikes and their crest level. Peculiar feature of the proposed calculated formulae is an interaction consideration of channel and inundated flows. Their mass-exchanging process results in slowing-down of the channel flow and acceleration of the inundated flow. This occurrence is taken into account and coefficients of kinematic efficiency are introduced to the elements of water flow rate in the river channel and flood plain, respectively. The adduced dependencies for determination of a dike crest level (consequently their height) take into consideration a rise of water level in inter-dike space for two types of polder systems: non-inundable (winter) dikes with maximum spring flood rate and inundable (summer) dikes with summer-autumn flood rates. The proposed calculated formulae can be recommended for application at design organizations.

scholarly journals Applying the Analytical Hierarchy Process (AHP) into the effects assessment of river training works

2017 ◽  
Vol 35 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Justyna Hachoł ◽  
Mateusz Hämmerling ◽  
Elżbieta Bondar-Nowakowska
Keyword(s):  
Decision Making ◽  
Sustainable Development ◽  
Optimal Solution ◽  
River Regulation ◽  
Analytic Hierarchy ◽  
The Sustainable Development ◽  
River Bed ◽  
River Training ◽  
The One ◽  
Hierarchy Process

AbstractThe aim of the following study was to compare a few methods of river regulations and indicate the one which fully meets technical regulative standard and concurrently ensures protection of the watercourse ecosystem. According to the sustainable development rules it is of the most importance in every human activity to compromise between developmental and environmental needs of current and future generations. Therefore, both technical criteria related to flood safety and environmental ones were taken into consideration in the analysis. Field study was conducted in vegetation stage between 2008 and 2014 in small and medium lowland watercourses in Lower Silesia. The research comprised of measurements and descriptions of selected technical and environmental elements of a complex system of the watercourse river bed. Basing on obtained results a multicriterial assessment of the effects of the works was conducted. In order to assess the results an Analytic Hierarchy Process (AHP) was used in the study. It facilitated the creation of linear ranking of river beds and indicate the most optimal solution in terms of sustainable development. Such methods have not been applied in solving problems connected with river regulation. That’s why this study aims also at checking the utility of this method in decision making in both planning and regulation works realization. Results of the study indicate high usefulness of AHP method in the decision-making process.

scholarly journals Biostratigraphy and paleoecology of continental Tertiary vertebrate faunas in the Lower Rhine Embayment (NW-Germany)

2002 ◽  
Vol 81 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Th. Mörs
Keyword(s):  
Depositional Environment ◽  
Middle Miocene ◽  
Flood Plain ◽  
Nw Germany ◽  
Climate Conditions ◽  
Faunal Assemblages ◽  
Tectonically Active ◽  
Lake Deposits ◽  
Lower Rhine Embayment ◽  
Lower Rhine

AbstractThis paper discusses the faunal content, the mammal biostratigraphy, and the environmental ecology of three important continental Tertiary vertebrate faunas from the Lower Rhine Embayment. The sites investigated are Rott (MP 30, Late Oligocene), Hambach 6C (MN 5, Middle Miocene), Frechen and Hambach 11 (both MN 16, Late Pliocene). Comparative analysis of the entire faunas shows the assemblages to exhibit many conformities in their general composition, presumably resulting from their preference for wet lowlands. It appears that very similar environmental conditions for vertebrates reoccurred during at least 20 Ma although the sites are located in a tectonically active region with high subsidence rates. Differences in the faunal composition are partly due to local differences in the depositional environment of the sites: lake deposits at the margin of the embayment (Rott), coal swamp and estuarine conditions in the centre of the embayment (Hambach 6C), and flood plain environments with small rivulets (Frechen and Hambach 11). The composition of the faunal assemblages (diversity and taxonomy) also documents faunal turnovers with extinctions and immigrations (Oligocene/Miocene and postMiddle Miocene), as a result of changing climate conditions.Additional vertebrate faunal data were retrieved from two new assemblages collected from younger strata at the Hambach mine (Hambach 11C and 14). They are important for the understanding of the Plio-Pleistocene transition in the southern part of the Lower Rhine Embayment and for correlating depositional sequences in the Dutch/German borderland.

scholarly journals Evidence of, and a Proposed Explanation for, Bimodal Transport States in Alluvial Rivers

2017 ◽  
Author(s):  
Kieran B. J. Dunne ◽  
Douglas J. Jerolmack
Keyword(s):  
Grain Size ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
Bed Load ◽  
Bed Sediments ◽  
Channel Geometry ◽  
Alluvial Rivers ◽  
River Bed ◽  
Tentative Evidence ◽  
Near Threshold

Abstract. Gravel-bedded rivers organize their bankfull channel geometry and grain size such that shear stress is close to the threshold of motion. Sand-bedded rivers on the other hand typically maintain bankfull fluid stresses far in excess of threshold, a condition for which there is no satisfactory understanding. A fundamental question arises: Are bed-load (gravel-bedded) and suspension (sand-bedded) rivers two distinct equilibrium states, or do alluvial rivers exhibit a continuum of transport regimes as some have recently suggested? We address this question in two ways: (1) re-analysis of global channel geometry datasets, with consideration of the dependence of critical shear stress upon site-specific characteristics (e.g. slope and grain size); and (2) examination of a longitudinal river profile as it transits from gravel to sand-bedded. Data reveal that the transport state of alluvial river-bed sediments is bimodal, showing either near-threshold or suspension conditions, and that these regimes correspond to the respective bimodal peaks of gravel and sand that comprise natural river-bed sediments. Sand readily forms near-threshold channels in the laboratory and some field settings, however, indicating that another factor, such as bank cohesion, must be responsible for maintaining suspension channels. We hypothesize that alluvial rivers adjust their geometry to the threshold-limiting bed and bank material – which for gravel-bedded rivers is gravel, but for sand-bedded rivers is mud (if present) – and present tentative evidence for this idea.

scholarly journals Late Oligocene macrofloras from fluviatile siliciclastic facies of the Köln Formation at the south-eastern border of the Lower Rhine Embayment (North Rhine-Westphalia, Germany)

2016 ◽  
Vol 56 (1) ◽  
pp. 41-64 ◽  
Author(s):  
Heinrich Winterscheid ◽  
Zlatko Kvaček
Keyword(s):  
Riparian Forest ◽  
Flood Plain ◽  
Volcanic Field ◽  
Late Oligocene ◽  
The South ◽  
South Eastern ◽  
Eastern Border ◽  
Leaf Remains ◽  
Lower Rhine Embayment ◽  
Lower Rhine

Abstract The leaf remains described herein came from the oldest sites of the Cainozoic deposits in the Lower Rhine Embayment, located in the Siebengebirge Volcanic Field at the south-eastern border of this basin, in the area of Siebengebirge and vicinity. These revisited floras are bound to pre-volcanic siliciclastic facies of the Siebengebirge Mts., interpreted as marginal facies of the Köln Formation. Chronostratigraphically they are assigned to the late Oligocene (Chattian). The described leaf remains are partially compressions with preserved epidermal anatomy, and therefore highly useful for systematic determination of leaf impressions recovered from other localities of siliciclastic facies. On account of the epidermal characteristics of leaf compressions varying in gross morphology, the previously determined taxa Quercus goepperti, Laurus phoeboides, and Persea speciosa all fall into the abundantly represented Eotrigonobalanus furcinervis. The siliciclastic deposits originated in coastal and flood plain areas within fluviatile environments of variable deposition energy. Remains of Taxodium dubium, Eotrigonobalanus furcinervis, Populus germanica, and Daphnogene cinnamomifolia dominate among the recovered fossils. The general aspects of this plant assemblage correspond, together with their sedimentary settings, to riparian forest vegetation with mesophytic elements.

scholarly journals The Spatial Distribution of Bed Sediment on Fluvial System: A Mini Review of the Aceh Meandering River

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Muhammad Irham
Keyword(s):  
Spatial Distribution ◽  
Bed Load ◽  
Sieve Analysis ◽  
Left Bank ◽  
Fluvial System ◽  
Dynamic Interactions ◽  
Meandering River ◽  
River Bed ◽  
Meander Bends ◽  
Mechanical Weathering

Dynamic interactions of hydrological and geomorphological processes in the fluvial system result in accumulated deposit on the bed because the capacity to carry sediment has been exceeded. The bed load of the Aceh fluvial system is primarily generated by mechanical weathering resulting in boulders, pebbles, and sand, which roll or bounce along the river bed forming temporary deposits as bars on the insides of meander bends, as a result of a loss of transport energy in the system. This dynamic controls the style and range of deposits in the Aceh River. This study focuses on the spatial distribution of bed-load transport of the Aceh River. Understanding the spatial distribution of deposits facilitates the reconstruction of the changes in controlling factors during accumulation of deposits. One of the methods can be done by sieve analysis of sediment, where the method illuminates the distribution of sediment changes associated with channel morphology under different flow regimes. Hence, the purpose of this mini review is to investigate how the sediment along the river meander spatially dispersed. The results demonstrate that channel deposits in the Aceh River are formed from four different type of materials: pebble deposited along upstream left bank; sand located on the upstream, downstream, and along meander belts; and silt and clay located along the cut bank of meander bends. Because of different depositional pattern, the distribution of the sediment along the river can be used as a surrogate to identify bank stability, as well as to predict critical geometry for meander bend initiation

scholarly journals VARIABILITY OF SEDIMENT TRANSPORT IN THE SCOTT RIVER CATCHMENT (SVALBARD) DURING THE HYDROLOGICALLY ACTIVE SEASON OF 2009

2014 ◽  
Vol 33 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Waldemar Kociuba ◽  
Grzegorz Janicki ◽  
Krzysztof Siwek
Keyword(s):  
Bedload Transport ◽  
Bed Load ◽  
River Catchment ◽  
Active Season ◽  
Fluvial Transport ◽  
River Bed ◽  
Load Transport ◽  
Bed Load Transport ◽  
Glacial River ◽  
Local Intensity

Abstract Investigations of fluvial transport in the glacial river catchment (Scott River, Spitsbergen) were conducted in the melt season of 2009. A special attention was given to dynamics and distribution of bedload transport − the major component of fluvial transport in a proglacial gravel-bed river. Bed-load transport rate was determined using the River Bedload Traps (RBT) constructed for the project’s need. The obtained results indicate high diversity of bedload transport, the amount of which reached up to 220 kg m-1 day-1 for twenty-four hours in particular measurement sites. The results confirmed also great variability of local intensity fluvial processes in polar zone.

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