scholarly journals Morphological changes and riffle-pool dynamics related to flow in a meandering river channel based on a 5-year monitoring period using close-range remote sensing

Geomorphology ◽  
2020 ◽  
Vol 352 ◽  
pp. 106982 ◽  
Author(s):  
J. Salmela ◽  
E. Kasvi ◽  
M.T. Vaaja ◽  
H. Kaartinen ◽  
A. Kukko ◽  
...  
2002 ◽  
Vol 45 (11) ◽  
pp. 55-62 ◽  
Author(s):  
P.J. Whalen ◽  
L.A. Toth ◽  
J.W. Koebel ◽  
P.K. Strayer

Channelization of the Kissimmee River transformed a 167 km meandering river into a 9 metre deep, 75 metre wide, 90 km drainage canal (C-38) that is compartmentalized with levees and water control structures into a series of five stagnant pools. Channelization dramatically changed water level and flow characteristics, drained 21,000 hectares of floodplain wetlands and severely impacted fish and wildlife populations. A $500 million dollar restoration project will restore the ecological integrity of the river-floodplain system by reconstructing the natural river channel and reestablishing hydrologic processes. Sixty expectations have been established to quantify the ecosystem's recovery. The first phase of reconstruction was completed in February 2001 and included movement of 9.2 million cubic metres of earth to backfill 12 km of C-38, the explosive demolition of one water control structure, construction of two sections (2.4 km) of new river channel, and reestablishment of 24 contiguous km of river. Numerous social, political, and technical challenges have been encountered during the project's evolution. Recommendations are provided for future restoration projects.


2022 ◽  
Vol 14 (2) ◽  
pp. 370
Author(s):  
Cameron Proctor ◽  
Cedelle Pereira ◽  
Tian Jin ◽  
Gloria Lim ◽  
Yuhong He

Efforts to monitor terrestrial decomposition dynamics at broad spatial scales are hampered by the lack of a cost-effective and scalable means to track the decomposition process. Recent advances in remote sensing have enabled the simulation of litter spectra throughout decomposition for grasses in general, yet unique decomposition pathways are hypothesized to create subtly different litter spectral signatures with unique ecosystem functional significance. The objectives of this study were to improve spectra–decomposition linkages and thereby enable the more comprehensive monitoring of ecosystem processes such as nutrient and carbon cycles. Using close-range hyperspectral imaging, litter spectra and multiple decomposition metrics were concurrently monitored in four classes of naturally decayed litter under four decomposition treatments. The first principal component accounted for approximately 94% of spectral variation in the close-range imagery and was attributed to the progression of decomposition. Decomposition-induced spectral changes were moderately correlated with the leaf carbon to nitrogen ratio (R2 = 0.52) and sodium hydroxide extractables (R2 = 0.45) but had no correlation with carbon dioxide flux. Temperature and humidity strongly influenced the decomposition process but did not influence spectral variability or the patterns of surface decomposition. The outcome of the study is that litter spectra are linked to important metrics of decomposition and thus remote sensing could be utilized to assess decomposition dynamics and the implications for nutrient recycling at broad spatial scales. A secondary study outcome is the need to resolve methodological challenges related to inducing unique decomposition pathways in a lab environment. Improving decomposition treatments that mimic real-world conditions of temperature, humidity, insolation, and the decomposer community will enable an improved understanding of the impacts of climatic change, which are expected to strongly affect microbially mediated decomposition.


2020 ◽  
Vol 12 (22) ◽  
pp. 3690 ◽  
Author(s):  
Angela Lausch ◽  
Michael E. Schaepman ◽  
Andrew K. Skidmore ◽  
Sina C. Truckenbrodt ◽  
Jörg M. Hacker ◽  
...  

The status, changes, and disturbances in geomorphological regimes can be regarded as controlling and regulating factors for biodiversity. Therefore, monitoring geomorphology at local, regional, and global scales is not only necessary to conserve geodiversity, but also to preserve biodiversity, as well as to improve biodiversity conservation and ecosystem management. Numerous remote sensing (RS) approaches and platforms have been used in the past to enable a cost-effective, increasingly freely available, comprehensive, repetitive, standardized, and objective monitoring of geomorphological characteristics and their traits. This contribution provides a state-of-the-art review for the RS-based monitoring of these characteristics and traits, by presenting examples of aeolian, fluvial, and coastal landforms. Different examples for monitoring geomorphology as a crucial discipline of geodiversity using RS are provided, discussing the implementation of RS technologies such as LiDAR, RADAR, as well as multi-spectral and hyperspectral sensor technologies. Furthermore, data products and RS technologies that could be used in the future for monitoring geomorphology are introduced. The use of spectral traits (ST) and spectral trait variation (STV) approaches with RS enable the status, changes, and disturbances of geomorphic diversity to be monitored. We focus on the requirements for future geomorphology monitoring specifically aimed at overcoming some key limitations of ecological modeling, namely: the implementation and linking of in-situ, close-range, air- and spaceborne RS technologies, geomorphic traits, and data science approaches as crucial components for a better understanding of the geomorphic impacts on complex ecosystems. This paper aims to impart multidimensional geomorphic information obtained by RS for improved utilization in biodiversity monitoring.


2012 ◽  
Vol 44 (4) ◽  
pp. 737-746 ◽  
Author(s):  
Qiang Zhang ◽  
Kun Li ◽  
Vijay P. Singh ◽  
Xiaohong Chen ◽  
Jianfeng Li

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.


2016 ◽  
Author(s):  
O. Nevalainen ◽  
E. Honkavaara ◽  
T. Hakala ◽  
Sanna Kaasalainen ◽  
N. Viljanen ◽  
...  

2020 ◽  
Vol 12 (20) ◽  
pp. 3361
Author(s):  
Przemysław Kuras ◽  
Łukasz Ortyl ◽  
Tomasz Owerko ◽  
Marek Salamak ◽  
Piotr Łaziński

This article describes a case of using remote sensing during a static load test of a large bridge, which, because of its location, belongs to a critical city infrastructure. The bridge in question is the longest tram flyover in Poland. This is an extradosed-type concrete structure. It conducts a long tram line over 21 other active lines of an important railway station in the center of Cracow. The diagnostic of such bridges involving the load test method is difficult. Traditional, contact measurements of span displacements are not enough anymore. In such cases, remote sensing becomes an indispensable solution. This publication presents an example of using the close-range radar remote sensing technique of ground-based radar interferometry. However, the cross-sections of the huge bridge were observed using several methods. The aim was to confirm the conditions and efficiency of radar displacement measurements. They were therefore traditional contact measurements using mechanic sensors conducted, if possible, to the bottom of the span, for precise leveling and measurement using electronic total station. Comparing the results as well as the discussion held demonstrated the fundamental advantages of remote sensing methods over the other more traditional techniques.


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