Land Degradation Processes and Fluvial Geomorphology: Intra/Inter-catchment Sediment Dynamics and Catchment Processes

A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Natural Hazards".

Deadline for manuscript submissions: closed (31 December 2017) | Viewed by 13497

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Soil Physics and Land Management, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
Interests: geomorphological processes; sustainable land management; land degradation and remediation; quaternary environments; climate change mitigation and adaptation; online learning
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Special Issue Information

Dear Colleagues,

Running water is an integral process in modifying and shaping the landscapes of the Earth. The ability of water to interact with the surrounding geology, soil, and detrital materials, helps to shape the characteristics of a catchment. Furthermore, the interface between erosion and depositional processes within catchments provides a myriad of catchment responses and drainage forms, such as rilling, gullies, ravines, canyons, and river valleys. Sediment budgets delivered from catchments to river valleys represent the culmination of soil erosion and land degradation processes (through anthropogenic and/or natural processes). Furthermore, time and spatial dimensions associated with these processes can vary dramatically. Eroded sediments can be stored within catchments for millennia yet they can be rapidly mobilized downstream due to extreme rainfall or flood event or anthropogenic activities which can ultimately impact the form and character of fluvial systems downstream. Despite the relatively short duration of floods from both rain and meltwater floods, they can significantly interrupt the interaction between water and landscapes. These sudden episodic processes can generate significantly more erosion and sediment in these short, high-intensity bursts than over low and moderate flows through the normal actions of a river. This Special Issue highlights the role of soil erosion processes within catchments and their impact on fluvial forms and riverine processes over a broad range of spatial and temporal scales and under varying climates. Therefore, studies focussed on landscape denudation, soil erosion and land degradation processes, sediment and hydrological dynamics, catchment hydrological processes, tracing techniques, fluvial processes, channel morphology and channel processes are most welcomed, as are studies into land and catchment management-related research. Early career researchers are encouraged to submit their research

Dr. Jerry Maroulis
Guest Editor

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Keywords

  • catchment processes
  • soil erosion
  • fluvial geomorphology
  • sediment dynamics
  • soil; land degradation
  • channel morphology

Published Papers (3 papers)

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Research

30 pages, 5828 KiB  
Article
Fluvial Geomorphology, Root Distribution, and Tensile Strength of the Invasive Giant Reed, Arundo Donax and Its Role on Stream Bank Stability in the Santa Clara River, Southern California
by Jiana E. Stover, Edward A. Keller, Tom L. Dudley and Eddy J. Langendoen
Geosciences 2018, 8(8), 304; https://doi.org/10.3390/geosciences8080304 - 14 Aug 2018
Cited by 16 | Viewed by 4217
Abstract
Arundo donax (giant reed) is a large, perennial grass that invades semi-arid riparian systems where it competes with native vegetation and modifies channel geomorphology. For the Santa Clara River, CA, changes in channel width and intensity of braiding over several decades are linked [...] Read more.
Arundo donax (giant reed) is a large, perennial grass that invades semi-arid riparian systems where it competes with native vegetation and modifies channel geomorphology. For the Santa Clara River, CA, changes in channel width and intensity of braiding over several decades are linked in part to high flow events that remove A. donax. Nevertheless, the area of A. donax at the two study sites increased fivefold over a period of 28 years at one site and fourfold over 15 years at the second site. Effects of A. donax on bank stability are compared to those of a common native riparian tree—Salix laevigata (red willow)—at two sites on the banks and floodplain of the Santa Clara River. There is a significant difference of root density of A. donax compared to S. laevigata and the latter has a higher number of roots per unit area at nearly all depths of the soil profile. Tensile root strength for S. laevigata (for roots of 1–6 mm in diameter) is about five times stronger than for A. donax and adds twice the apparent cohesion to weakly cohesive bank materials than does A. donax (8.6 kPa compared to 3.3 kPa, respectively). Modeling of bank stability for banks of variable height suggests that S. laevigata, as compared to A. donax, increases the factor of safety (FS) by ~60% for banks 1 m high, ~55% for banks 2 m high and ~40% for banks 3 m high. For 3 m high banks, the FS for banks with A. donax is <1. This has geomorphic significance because, in the case of A. donax growing near the water line of alluvial banks, the upper 10–20 cm has a hard, resistant near-surface layer overlying more erodible banks just below the near-surface rhizomal layer. Such banks may be easily undercut during high flow events, resulting in overhanging blocks of soil and A. donax that slump and collapse into the active channel, facilitating lateral bank erosion. Therefore, there is a decrease in the lateral stability of channels if the mixed riparian forest is converted to dominance by A. donax. Full article
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17 pages, 10648 KiB  
Article
Temporal and Spatial Variability of Sediment Transport in a Mountain River: A Preliminary Investigation of the Caldone River, Italy
by Davide Brambilla, Monica Papini and Laura Longoni
Geosciences 2018, 8(5), 163; https://doi.org/10.3390/geosciences8050163 - 04 May 2018
Cited by 6 | Viewed by 4289
Abstract
Sediment transport is a key evolution process of rivers and water basins. This process can pose flood hazards to nearby areas. The Eulerian and Lagrangian methods are usually employed to describe sediment transport in mountain rivers. The application of different methods was proposed [...] Read more.
Sediment transport is a key evolution process of rivers and water basins. This process can pose flood hazards to nearby areas. The Eulerian and Lagrangian methods are usually employed to describe sediment transport in mountain rivers. The application of different methods was proposed by scientists to analyze specific aspects of solid transport, however a complete understanding still alludes us. After a brief review of the most common methods, the coupling of three different methods is proposed and tested in order to study sediment dynamics, and its spatial and temporal variability, in mountain rivers. Tracers, painted bed patches, and digital elevation model (DEM) comparisons are used to characterize sediment transport at both a micro-scale short-term and a macro-scale long-term level on a test reach on Caldone River, Italy. Information about travel distance, critical diameters, active width, and morphological evolution was sought. We focused on how water discharge is changing the relationships between different measurement techniques. High discharge events force the channel to behave in a unique way, while low discharge events generate more intrinsic variability. Only measurement technique coupling can overcome this issue. Results are encouraging and show the potential of a mixed Eulerian-Lagrangian approach. Full article
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17 pages, 5195 KiB  
Article
Multibeam Bathymetric Investigations of the Morphology and Associated Bedforms, Sulina Channel, Danube Delta
by Florin Duţu, Nicolae Panin, Gabriel Ion and Laura Tiron Duţu
Geosciences 2018, 8(1), 7; https://doi.org/10.3390/geosciences8010007 - 02 Jan 2018
Cited by 8 | Viewed by 4199
Abstract
In the Danube Delta, on the Sulina branch, the morphology, sediment, and bedform characteristics were investigated. Three-dimensional (3D) bathymetry, flow velocity, suspended-load concentration, and liquid and solid discharge data were acquired throughout several cross sections along the Sulina channel, in order to investigate [...] Read more.
In the Danube Delta, on the Sulina branch, the morphology, sediment, and bedform characteristics were investigated. Three-dimensional (3D) bathymetry, flow velocity, suspended-load concentration, and liquid and solid discharge data were acquired throughout several cross sections along the Sulina channel, in order to investigate the distribution of water and sediment discharges and their influence against the river bed. A single observation (in February 2007) was made regarding the geometry, sediment composition, and hydraulic conditions under which the dunes grew and degenerated. The investigation focuses here mostly on the geometrical parameters of these bedforms, such as height, length, as well as grain size characteristic of the sediment and water dynamics. Based on in-site measurements, different hydraulic parameters were calculated, such as bed shear stresses and Reynolds number. During the field campaign, the measured water mean velocity was from v = 0.22–1.13 m∙s−1. At the same time, the measured range of shear stresses within the dune field formation was from τ0 = 2.86 N·m−2 (on the cutoffs) to 8.62 N·m−2 (on the main channel). It was found that the correlation between height (H) and length (L) of the Sulina branch dunes describes the formula: H = 0.093L0.5268. The bedforms of the Sulina channel are, in general, developed in fine sand (D50 between 0.06 and 0.35 mm). Full article
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