Reservoir effects on downstream river channel migration

2000 ◽  
Vol 27 (1) ◽  
pp. 54-66 ◽  
Author(s):  
F. DOUGLAS SHIELDS JR ◽  
ANDREW SIMON ◽  
LYLE J. STEFFEN
Keyword(s):  
Flood Control ◽  
Habitat Type ◽  
River Channel ◽  
Aerial Photographs ◽  
Lateral Migration ◽  
Widespread Application ◽  
Ecosystem Integrity ◽  
Migration Rates ◽  
Alluvial River ◽  
River Floodplains

Human occupation and development of alluvial river floodplains are adversely affected by river channel lateral migration, which may range as high as several hundred metres per year. Reservoirs that reduce the frequency and duration of high flows typically reduce lateral migration rates by factors of 3 to 6. The ecology of riverine corridors is dependent upon the processes of erosion and sedimentation, which lead to lateral migration. Multiple-objective use of floodplains adjacent to active rivers therefore requires tools for assessing the probability and magnitude of channel movements. Existing approaches for predicting river channel movement may be classified as empirical or mechanistic, and are inadequate for widespread application. The Missouri River downstream from Fort Peck Dam in Montana, a major alluvial river with flow highly perturbed by regulation, was selected for case study. Maps and aerial photographs were available before and after dam construction. This imagery was analysed by digitizing channel centrelines at successive coverages under pre-dam and post-dam conditions, and mean migration rates were computed by bend and by reach. The mean rate of channel centreline migration fell from 6.6 m yr-1 to 1.8 m yr-1 after impoundment. Bend-mean channel activity rates were only weakly correlated with variables describing channel form and geometry. Results indicate that flow regulation for flood control and hydropower production typical of the study reach had profound effects on river corridor dynamism, with implications for habitat type distribution and ecosystem integrity.

scholarly journals Temporal and spatial variation of Myriapoda (Diplopoda and Chilopoda) assemblages in a Neotropical floodplain

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Lorhaine Santos-Silva ◽  
Tamaris Gimenez Pinheiro ◽  
Amazonas Chagas-Jr ◽  
Marinêz Isaac Marques ◽  
Leandro Dênis Battirola
Keyword(s):  
Spatial Variation ◽  
Habitat Type ◽  
Temporal Distribution ◽  
High Water ◽  
Trophic Levels ◽  
Temporal And Spatial Variation ◽  
Ecosystem Integrity ◽  
Mato Grosso ◽  
Temporal And Spatial ◽  
Hydrological Cycles

Abstract: Myriapods constitute important edaphic macrofauna taxa which dwell in different trophic levels and influence the dynamics of these environments. This study evaluated the variation in composition, richness and abundance of edaphic myriapod assemblages as a function of the distribution and structure of flooded and non-flooded habitats (spatial variation) and hydrological seasonality (temporal variation) in a floodplain of the northern Pantanal region of Mato Grosso, Brazil. Sampling was carried out in three areas of the Poconé Pantanal, along an altitudinal and inundation gradient consisting of inundated and non-inundated habitats and different vegetation formations. Three quadrats (10 x 10 m) were delimited within each habitat type, where sampling was performed using pitfall traps and mini-Winkler extractors during the dry, rising water, high water and receding water periods of two hydrological cycles within the Pantanal (2010/2011 and 2011/2012). A total of 549 millipedes were collected, consisting of 407 Diplopoda and 142 Chilopoda distributed in six orders, 12 families and 20 species. The assemblages composition varied throughout the seasonal periods, indicating that the rising water and dry periods differed from the high water and receding water periods. In addition to the variation between seasonal periods, myriapod richness and abundance also varied in relation to areas consisting of different vegetation formations. Thus, it can be concluded that the hydrological seasonality associated with the inundation gradient and different vegetation types were determinant in the heterogeneous spatial and temporal distribution of myriapod assemblages, validating that the conservation of these invertebrates in the Pantanal is directly linked to the preservation of vegetation, and consequently, ecosystem integrity.

Upstream and downstream morphodynamic influence in simulated and real meandering rivers

2021 ◽  
Author(s):  
Hossein amini ◽  
Guido Zolezzi ◽  
Federico Monegaglia ◽  
Emanuele Olivetti ◽  
Marco Tubino
Keyword(s):  
Migration Rate ◽  
Machine Learning Techniques ◽  
Stochastic Gradient Descent ◽  
Support Vector ◽  
Lateral Migration ◽  
Remotely Sensed Data ◽  
Meandering Rivers ◽  
Meandering River ◽  
Migration Rates ◽  
Meander Migration

<p>This study investigates the dependency of meander lateral migration rates on the spatial distribution of channel centerline curvature in both synthetic and real meandering rivers. It employs Machine Learning techniques (hereafter ML) to relate observed local lateral meander migration rates with the local and the upstream/downstream values of the centerline curvature. To achieve this goal, it was primarily essential to identify the feasibility of using ML in the meandering river's morphodynamics. We then determined the ability of ML to predict the excess near bank velocity based a set of input data using different regression techniques (linear and polynomial, Stochastic Gradient Descent, Multi-Layer Perceptron, and Support Vector Machine). We then moved forward to study the upstream-downstream influence on local migration rate. Synthetic meandering river planforms, as obtained through the planform evolution model of Bogoni et al. (2017), which is based on Zolezzi and Seminara (2001) meander flow model, were used as test cases for the calibration and check of the different adopted ML algorithms. The calibrated algorithms were then applied to multi-temporal information on meander planform dynamics obtained through the PyRiS software (Monegaglia et al., 2018), to quantify to which extent the upstream and downstream distribution of meander centerline curvature affects the local meander migration rate in real rivers.</p><p>References </p><p>1- Zolezzi, G., & Seminara, G. (2001b). Downstream and upstream influence in river meandering. Part 1. General theory and application overdeepening. Journal of Fluid Mechanics, 438(September 2015), 183–211. https://doi.org/10.1017/S002211200100427X</p><p>2- Monegaglia, F., Zolezzi, G., Güneralp, I., Henshaw, A. J., & Tubino, M. (2018). Automated extraction of meandering river morphodynamics from multitemporal remotely sensed data. In Environmental Modelling & Software (Vol. 105, pp. 171–186). https://doi.org/10.1016/j.envsoft.2018.03.028</p><p>3- Bogoni, M., Putti, M., & Lanzoni, S. (2017). Modeling meander morphodynamics over self-formed heterogeneous floodplains. In Water Resources Research (Vol. 53, Issue 6, pp. 5137–5157). https://doi.org/10.1002/2017wr020726</p><p>4- Benozzo, D.,  Olivetti, E., Avesani, P. (2017). Supervised Estimation of Granger-Based Causality between Time series. In Frontiers in Neuroinformatics. </p><p>https://doi.org/10.3389/fninf.2017.00068 </p><p>5- Sharma A., Kiciman, E. (2020). DoWhy: An End-to-End library for Causal Inference. arXiv preprint arXiv:2011.04216. </p><p>https://arxiv.org/abs/2011.04216</p>

scholarly journals Assessment of the soil loss caused by riverbank erosion in Serbia

2021 ◽  
Vol 101 (1) ◽  
pp. 31-47
Author(s):  
Marko Langovic ◽  
Slavoljub Dragicevic ◽  
Ivan Novkovic ◽  
Nenad Zivkovic ◽  
Radislav Tosic ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Loss ◽  
Large Scale ◽  
Temporal Dynamics ◽  
Land Use Changes ◽  
Arable Land ◽  
Aerial Photographs ◽  
Lateral Migration ◽  
Channel Migration ◽  
Riverbank Erosion

Riverbank erosion and lateral channel migration are important geomorphological processes which cause various landscape, socio-economic, and environmental consequences. Although those processes are present on the territory of Serbia, there is no available data about the soil loss caused by riverbank erosion for the entire country. In this study, the spatial and temporal dynamics of the riverbank erosion for the largest internal rivers in Serbia (Velika Morava, Zapadna Morava, Juzna Morava, Pek, Mlava, Veliki Timok, Kolubara) was assessed using remote sensing and GIS. The aim of this paper is to determine the total and average soil loss over large-scale periods (1923-2020), comparing data from the available sources (aerial photographs, satellite images, and different scale paper maps). Results indicated that lateral migration caused significant problems through land loss (approximately 2,561 ha), especially arable land, and land use changes in river basins, but also economic loss due to the reduction of agricultural production. Total and average soil loss was calculated for five most representative meanders on all studied rivers, and on the basis of the obtained values, certain regularities about further development and dynamics of riverbank movement are presented. A better understanding of river channel migration in this area will be of a great importance for practical issues such as predicting channel migration rates for river engineering and planning purposes, soil and water management and land use changes, environment protection.

scholarly journals Changes in stage–flow relation of the East River, the Pearl River basin: causes and implications

2012 ◽  
Vol 44 (4) ◽  
pp. 737-746 ◽  
Author(s):  
Qiang Zhang ◽  
Kun Li ◽  
Vijay P. Singh ◽  
Xiaohong Chen ◽  
Jianfeng Li
Keyword(s):  
Water Level ◽  
River Basin ◽  
Flood Control ◽  
Morphological Changes ◽  
River Channel ◽  
Pearl River Basin ◽  
Abrupt Decrease ◽  
East River ◽  
The Pearl River ◽  
High Level

Water level and streamflow extracted from 891 hydrological episodes from both dry and flood seasons covering a period of 1954–2009 were analyzed to investigate stage–flow relations. Results indicate the following. (1) Since the early 1990s the low/high flow is increasing/decreasing. The water level, particularly the high level, is consistently decreasing. An abrupt decrease of water level is observed since the early 1990s at the lower East River. (2) Stage–streamflow relation is usually stable in the river reach with no significant bedform morphological changes. Changes in the geometric shape of the river channel are the major cause of the change in the stage–streamflow relation. (3) An abrupt decrease of water level at the Boluo station is mainly the result of abnormally rapid downcutting of the riverbed due to extensive sand dredging within the channel which caused serious headwater erosion. This human-induced modification by downcutting of the river channel may lead to significant hydrological alterations and may have critical implications for flood control, conservation of eco-environment, and also for basin-wide water resources management in the lower East River basin.

Determining lateral migration rates of meandering rivers using fallout radionuclides

Geomorphology ◽  
2010 ◽  
Vol 123 (3-4) ◽  
pp. 364-369 ◽  
Author(s):  
E. Black ◽  
C.E. Renshaw ◽  
F.J. Magilligan ◽  
J.M. Kaste ◽  
W.B. Dade ◽  
...  
Keyword(s):  
Lateral Migration ◽  
Meandering Rivers ◽  
Migration Rates ◽  
Fallout Radionuclides

A system using aerial photography to estimate area of root disease centers in forests

1978 ◽  
Vol 8 (2) ◽  
pp. 214-219 ◽  
Author(s):  
Ralph E. Williams ◽  
C. D. Leaphart
Keyword(s):  
Large Scale ◽  
Habitat Type ◽  
Root Disease ◽  
Aerial Photographs ◽  
National Forest ◽  
Forest Land ◽  
Habitat Types ◽  
Coeur D'alene ◽  
Commercial Forest ◽  
Northern Idaho

The area of root disease centers on the Coeur d'Alene National Forest in northern Idaho was effectively estimated from large-scale color infrared aerial photographs. An estimated 5.1% (12 160.7 ha) of the commercial forest land was occupied by infection centers. Root disease centers were identified in 113 of 364 stands actually surveyed. Although most of these 113 stands were of the Tsugaheterophylla – Pachistimamyrsinites habitat type, the highest percentage of stands with root disease was found in the Abiesgrandis – Pachistimamyrsinites habitat type.Observations made during these studies suggest that occurrence of Pseudotsugamenziesii (Mirb.) Franco, Abiesgrandis (Dougl.) Lindl., or both in a stand is the most important factor in the expression of root disease centers. Accuracy of interpretation of photographs was 92%; incorrect interpretations were consistently associated with stands in the Abieslasiocarpa series of habitat types or with stands stocked with conifers tolerant of root pathogens.

Aperiodic embayed sandy beach rotation and erosion-risk exposure on a hyper-muddy wave-exposed coast

2020 ◽  
Author(s):  
Edward Anthony ◽  
Antoine Gardel ◽  
Morgane Jolivet ◽  
Guillaume Brunier ◽  
Franck Dolique
Keyword(s):  
Field Experiments ◽  
Leading Edge ◽  
Aerial Photographs ◽  
Sand Transport ◽  
Shoreline Development ◽  
Migration Rates ◽  
Longshore Transport ◽  
Mud Bank ◽  
Beach Rotation

<p><span>The 1500 km-long wave-exposed coast of the Guianas, South America, is characterized at any time by up to 20+ large distinct mud banks with suspended mud concentrations of up to 1000 g/l migrating from the Amazon delta to the Orinoco delta under the influence of wave-driven longshore transport. Banks can be up to 60 km-long, strongly dissipate waves, and are separated alongshore by ‘inter-bank’ sectors of similar length. The latter are affected by shoreward propagation of much less dissipated waves that can generate rapid muddy shoreline erosion and reworking of beaches and cheniers formed from sand supplied by rivers draining the crystalline rocks of the Guiana Shield.</span></p><p><span>About 500 km northwest of the mouths of the Amazon, the pervasive mud and its effects on the nearshore wave regime determine, for the embayed, headland-bound beaches in French Guiana, outcomes that are important  from a long-term management perspective. These beaches have come under urban pressures and assure recreational and ecological functions such as provision of nesting sites for marine turtles. The sand-mud interactions, processes of sand segregation from mud, sediment transport modes, and morphodynamics associated with these beaches over timescales ranging from weeks to several decades, were analyzed from aerial photographs, satellite images, aerial photogrammetry, and field experiments. The longer bay beaches are exposed to longshore transport when mud is temporarily scarce (inter-bank phases), and subject in parts to overwash. During inter-bank phases, ‘normal’ westward sand transport along these beaches is generated by waves from E to NE, but is counter-balanced during bank phases by eastward drift at the leading edge of a bank as waves are refracted over the bank. This counter-drift prevails at a ‘mobile’ rotation front that moves with the bank’s leading edge migrating at rates of 1 to 2.5 km a year. As the bank passes, it further shelters beaches from wave reworking, with eventual re-exposure to waves and ‘normal’ drift following complete mud-bank passage. In the context of the ‘closed’ sand budget of these beaches, headlands spatially constrain sand mobility, and the unique mode of rotation induced by mud-bank refraction of waves plays an important role by counter-balancing unidirectional longshore transport that could otherwise result in permanent deprivation of updrift beach sectors of sand. Due to variability in bank-migration rates and spacing, normal drift and counter-drift may prevail, respectively, over periods exceeding two years but of unknown duration. The variability of this time frame of rotation poses a challenge to the implementation of set-back lines necessary to avoid the impingement of urbanization and sea-front activities on the long-term (>decadal) bandwidth of beach affected by rotation, which involves aperiodic and variable erosion and accretion in different parts of the beach. In this context of aperiodic beach rotation, prediction of mud-bank migration rates downdrift of the Amazon and of the imminent arrival of a mud bank, coupled with the firm implementation of shoreline development setback lines, are necessary to mitigate risks from erosion and overwash events.    </span></p>

scholarly journals Early Holocene alluvia in the lower Wisłok River valley and their chronostratigraphy in the light of radiocarbon datings and palynological analysis

2017 ◽  
Vol 44 (1) ◽  
pp. 216-225
Author(s):  
Sławomir Superson ◽  
Piotr Gębica ◽  
Adam Michczyński ◽  
Piotr Kołaczek ◽  
Kazimierz Szczepanek
Keyword(s):  
Radiocarbon Dating ◽  
River Channel ◽  
River Valley ◽  
Early Holocene ◽  
Lateral Migration ◽  
Probability Level ◽  
Palynological Analysis ◽  
High Terrace ◽  
Organic Sediments ◽  
Radiocarbon Datings

Abstract The paper presents the results of the latest radiocarbon dating and the palynological analyses of organic sediments found in the alluvia of the Wisłok River valley between the towns of Łańcut and Przeworsk. The study conducted in the gravel pit made possible the dating of several alluvial fills of the 7–8 m high Holocene terrace and the 5–6 m high floodplain. The oldest channel alluvia and palaeochannel sediments of the 7–8 m high terrace were dated at 10 100–9300 BP (11 960–10 500 cal BP). According to the anthracological analysis the top cover of clay overbank alluvia, which bears charcoal fragments, was deposited in the Subboreal and/or the Subatlantic Phases. In the sequence of the 5–6 m high floodplain, the bottom fills of palaeochannels, dated at 10 195–9885 cal BP (probability level: 68.2%; GdS-3233: 8900 ± 95 BP ) and 11 095–10 755 cal BP (probability level: 68.2%; GdS-3228: 9575 ± 95 BP), were truncated by erosion and covered by alluvia of palaeomeanders, which were active in the 19th century. Preservation of the erosional bench of the Early Holocene organic sediments indicates the predomination of lateral migration of the river channel during the last 200 years and the formation of wide erosional floodplain that has been aggraded with recent flood alluvia. In the 20th century the floodplain aggradation was simultaneous with the deepening of the Wisłok riverbed.

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