Multidisciplinary approach to sediment connectivity between debris-flow channel network and the Dolra River, Mazeri Valley, Southern Caucasus, Georgia

Geomorphology ◽  
2020 ◽  
Vol 371 ◽  
pp. 107455
Author(s):  
Daniel Germain ◽  
Ionela-Georgiana Gavrilă ◽  
Mariam Elizbarashvili ◽  
Olimpiu Traian Pop
Keyword(s):  
Debris Flow ◽  
Multidisciplinary Approach ◽  
Flow Channel ◽  
Channel Network ◽  
Sediment Connectivity ◽  
Southern Caucasus

Dendrogeomorphic reconstruction of debris-flow activity in Mazeri Valley, Greater Caucasus, Georgia

2021 ◽  
Author(s):  
Olimpiu Pop ◽  
Daniel Germain ◽  
Ionela-Georgiana Gavrilǎ ◽  
Mariam Elizbarashvili
Keyword(s):  
Debris Flow ◽  
High Altitude ◽  
Temporal Dynamics ◽  
Flow Channel ◽  
Channel Network ◽  
Sediment Fluxes ◽  
Greater Caucasus ◽  
Braided Channel ◽  
Dynamic Landscape ◽  
Flow Activity

<p>The Mazeri Valley in the Greater Caucasus (Georgia) is characterized by a highly dynamic landscape with several active mass-wasting processes. The spatial and temporal dynamics of these geomorphic processes have, over time, resulted in the formation of large cones and fans. In this context, the coupling between the hillslope and the channel plays a fundamental role in controlling the catchment sediment dynamics. The sediment produced at higher altitudes on hillslopes may occasionally reach the debris-flow channel network, and downstream propagation may have significant effects on the fluvial environment and create potential hazards for the resident population, tourists and infrastructures. In this study, we aim to better understand sediment fluxes in the mountain headwater stream in the Mazeri Valley. In this regard, a tree-ring-based chronology of the debris-flow activity on a large cone was created, to shed light on sediment connectivity and better understand the coupling between the main debris-flow channel and the bedload of Dolra river. The 161 disturbed trees sampled allowed to reconstruct a minimum of 12 significant debris-flow events over the last 65 years, with all of these events involving possible sediment input into the stream system of the Dolra river. These successional events, with a return interval of 5.4 years, have partially destabilized the fluvial system and locally induced a switch in the channel style to a braided channel. Although the cone studied is not directly located in a proglacial environment, its geomorphological dynamics remain highly dependent on water and sediment inputs from upstream, giving the presence of retreating glaciers and then paraglacial conditions at high altitude. The ongoing glacial retreat and increased climate variability will certainly lead to a massive output of sediments at high altitude, favoring an increase in geomorphic activity in the area. Many other fan and cone complexes are present in the Mazeri Valley, as well as in other adjacent valleys, and there are no documentations regarding their dynamics (e.g., typology, nature and source areas of hillslope processes, their coupling with channelized sediment-water flows, frequency–magnitude relationships). In this regard, we expect that the present pioneering study in this area will encourage more researches to investigate sediment fluxes for a better land use and preservation of water in Georgia under climate change.</p><p><em>Cette étude représente une contribution pour le projet « Impact du changement climatique sur les glaciers et les risques associés dans le Caucase Géorgien - IMPCLIM », financé par l’Agence Universitaire de la Francophonie (AUF) et le Ministère pour la Recherche et l'Innovation de Roumanie (MRI) à travers l'Institut Roumain de Physique Atomique (IFA).</em></p>

Post Wildfire Debris Flow and Flood Analysis of the September 2020 Badger Fire in the Trapper Creek and Rock Creek Watersheds, Idaho, USA.

2021 ◽  
Author(s):  
Stephen Turnbull ◽  
Nawa Pradhan ◽  
Ian Floyd
Keyword(s):  
Debris Flow ◽  
Finite Volume ◽  
Overland Flow ◽  
Frozen Ground ◽  
Channel Network ◽  
Hydrologic Analysis ◽  
Flood Analysis ◽  
Model Equations ◽  
Volume Method ◽  
Parameter Values

<p>There are several different infiltration, overland flow routing, and channel routing schemes that can be used in conjunction with recommended hydrodynamic and infiltration parameter values, which are found within the literature, to provide critical flooding assessments for stakeholders and decision makers.  We focus on post wildfire debris flow and flood analysis in two tributaries of the Snake River in Idaho, Trapper Creek and Rock Creek.  The Badger Fire started on September 12, 2020 in the Sawtooth National Forest in Idaho, USA, and burned sub-alpine fir, lodgepole pine, juniper, mountain brush and grass communities, in the upper part of both the Trapper Creek and Rock Creek watersheds.  Trapper Creek has a U.S. Geological Gaging station, and there are two snow gaging sites available.   The biggest concern for flooding and debris flow is the result of a wintertime rain-on-snow event, which resulted in the largest storm in the gaging record period.    </p><p>To estimate runoff in ungaged stream locations, existing process-based hydrodynamic models can be applied in a distributed form to solve the governing equations for mass, momentum and energy in a spatially explicit way. The purpose of this study is to predict potentially inundated land areas as a result of a rain-on-snow event, using the data in the gages basin to provide flood analysis information for both the gaged (Trapper Creek) and ungaged watershed (Rock Creek).  Rain-on-snow events are rainfall events that occur on the snowpack and frozen ground, resulting in a larger magnitude and volume of streamflow.  To predict these flows, Gridded Surface Subsurface Hydrologic Analysis (GSSHA) watershed models are prepared and calibrated to simulate rain-on-snow events in both watersheds.  The runoff generated from a two dimensional overland flow grid is transferred over land with a finite volume numerical method into a one dimensional channel network.  The channel network also uses a finite volume method.    The consistency in the identified range of the parametric values and their physical applicability make GSSHA an ideal candidate for this study, as the model equations provide a methods to evaluate a rain-on-snow event.</p>

Multi-temporal analysis of the role of check dams in a debris-flow channel: Linking structural and functional connectivity

Geomorphology ◽  
2019 ◽  
Vol 345 ◽  
pp. 106844 ◽  
Author(s):  
Sara Cucchiaro ◽  
Federico Cazorzi ◽  
Lorenzo Marchi ◽  
Stefano Crema ◽  
Alberto Beinat ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Debris Flow ◽  
Temporal Analysis ◽  
Flow Channel ◽  
Check Dams ◽  
Multi Temporal

Debris flow initiation from ravel-filled channel bed failure following wildfire in a bedrock landscape with limited sediment supply

2021 ◽  
Author(s):  
Marisa C. Palucis ◽  
Thomas P. Ulizio ◽  
Michael P. Lamb
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Sediment Supply ◽  
Moderate Intensity ◽  
Sandy Sediment ◽  
Channel Network ◽  
Sediment Yields ◽  
First Order ◽  
Dry Ravel ◽  
Debris Flow Initiation

Steep, rocky landscapes often produce large sediment yields and debris flows following wildfire. Debris flows can initiate from landsliding or rilling in soil-mantled portions of the landscape, but there have been few direct observations of debris flow initiation in steep, rocky portions of the landscape that lack a thick, continuous soil mantle. We monitored a steep, first-order catchment that burned in the San Gabriel Mountains, California, USA. Following fire, but prior to rainfall, much of the hillslope soil mantle was removed by dry ravel, exposing bedrock and depositing ∼0.5 m of sandy sediment in the channel network. During a one-year recurrence rainstorm, debris flows initiated in the channel network, evacuating the accumulated dry ravel and underlying cobble bed, and scouring the channel to bedrock. The channel abuts a plowed terrace, which allowed a complete sediment budget, confirming that ∼95% of sediment deposited in a debris flow fan matched that evacuated from the channel, with a minor rainfall-driven hillslope contribution. Subsequent larger storms produced debris flows in higher-order channels but not in the first-order channel because of a sediment supply limitation. These observations are consistent with a model for post-fire ravel routing in steep, rocky landscapes where sediment was sourced by incineration of vegetation dams—following ∼30 years of hillslope soil production since the last fire—and transported downslope by dry processes, leading to a hillslope sediment-supply limitation and infilling of low-order channels with relatively fine sediment. Our observations of debris flow initiation are consistent with failure of the channel bed alluvium due to grain size reduction from dry ravel deposits that allowed high Shields numbers and mass failure even for moderate intensity rainstorms.

Numerical Simulation Applied to Study the Effects of Fractal Tree-Liked Network Channel Designs on PEMFC Performance

2012 ◽  
Vol 488-489 ◽  
pp. 1219-1223 ◽  
Author(s):  
Shan Jen Cheng ◽  
Jr Ming Miao ◽  
Chang Hsien Tai
Keyword(s):  
Fuel Cell ◽  
Pressure Drop ◽  
Flow Field ◽  
Fluid Dynamic ◽  
Flow Distribution ◽  
Flow Channel ◽  
Proton Exchange ◽  
Channel Network ◽  
Computational Fluid Dynamic Analysis ◽  
Network Channel

The effect of pressure drop and the flow-field of inhomogeneous transport of reactions gas are two important issues for bipolar flow channel design in proton exchange membrane fuel cell (PEMFC). A novel design through the imitation of biological development of the topology distribution of fractal tree-liked network channel is the main topic of this research. The effects of different Reynolds numbers and stoichiometric mass flow rate of reaction gas on the flow field distribution of tree-like channels were investigated by three-dimensional computational fluid dynamic analysis. According to numerical simulations, the fractal tree-liked network channel would have an excellent performance on the uniformity of multi-branching flow distribution and lower pressure drop along channels. The new type of fractal tree-liked bionic flow channel network design will be applied to assist in the experimental reference for improving the performance of fuel cell stack system in PEMFC for future.

scholarly journals Debris‐flow‐dominated sediment transport through a channel network after wildfire

2020 ◽  
Vol 45 (5) ◽  
pp. 1155-1167
Author(s):  
Petter Nyman ◽  
Walter A.C. Box ◽  
Justin C. Stout ◽  
Gary J. Sheridan ◽  
Saskia D. Keesstra ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Debris Flow ◽  
Channel Network

Improving the Amplitude Source Location (ASL) Method Using Multicomponent Seismic Data: An Assessment with Active Source Seismic Data

2019 ◽  
Vol 110 (1) ◽  
pp. 250-269
Author(s):  
Braden Walsh ◽  
Jonathan Procter ◽  
Arthur Jolly
Keyword(s):  
Debris Flow ◽  
Seismic Data ◽  
Vertical Component ◽  
Source Location ◽  
Flow Channel ◽  
Coda Wave ◽  
F Test ◽  
Active Source ◽  
Mean Square Errors ◽  
Three Components

ABSTRACT Here, all three components of the seismic signal are applied for use with the amplitude source location (ASL) method to investigate if using all three components yield more accurate results than using just the vertical component. Eight active source events along a debris flow channel on Te Maari Volcano, New Zealand, are used as known source locations to conduct the test. Both coda-wave normalization (CWN) and horizontal-to-vertical (H/V) ratio methods are used to calculate amplification factors for station corrections. Average location errors for all the active seismic sources varied between 0.47 km for the vertical component and 0.51 km for three components while using the CWN method, and 0.92 km (vertical) and 0.83 km (three component) using the H/V method. We also conduct statistical analysis through an F-test by calculating root mean square errors (RMSEs) to determine if the results were statistically different. The RMSE analysis for the active source events shows location results for event 1 and 7 producing errors of 2.18±1.33 and 2.37±1.29  km for the vertical-component results, and 2.06±1.16 and 2.33±1.24  km for the three-component results. The F-test indicates that active source events higher up the debris flow channel (centrally located relative to the network) are statistically the same, whereas events lower down the channel (away from the center of the network) are statistically different. Results show that using all three components with the ASL method may not necessarily yield more accurate locations, but nevertheless may average the components to eliminate the extreme error values or amplify the signals, producing more precise results.

scholarly journals Evaluating Factors for Controlling Sediment Connectivity of Landslide Materials: A Flume Experiment

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 17 ◽  
Author(s):  
Hefryan Sukma Kharismalatri ◽  
Yoshiharu Ishikawa ◽  
Takashi Gomi ◽  
Roy C. Sidle ◽  
Katsushige Shiraki
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Sedimentary Rock ◽  
Landslide Dam ◽  
Main Channel ◽  
Fluvial Systems ◽  
Weathered Granite ◽  
Landslide Dams ◽  
Key Factor ◽  
Sediment Connectivity

Connectivity of landslide sediment to and within fluvial systems is a key factor affecting the extent of mobilization of hillslope material. In particular, the formation of landslide dams and the transformation into landslide-induced debris flows represent “end members” of landslide sediment mobility. To quantify sediment connectivity, we developed a two-segment flume representing tributary inflow and the main channel. Mobility of sediment was examined by combinations of various topographic factors, such as tributary inflow angle (0 to 90° in 30° increments) and main channel gradient (10° and 15°), as well as water content of sediment (0 to 100% in 20% increments). We also examined differences of mobility among sediments derived from various lithologies (sand and shale, pyroclastic sediment, weathered granite, and weathered sedimentary rock). Mobility of sediment differed, depending on the water content of sediment, particularly less than saturation or greater than saturation. When all types of unsaturated landslide sediments entered the channel at inflow angles of 60° and 90°, substantial deposition occurred, suggesting the formation of landslide dams. At low inflow angles (0° and 30°) in a steep channel (15°), >50% of landslide sediment was transported downstream, indicating the occurrence of a debris flow. The amount of sediment deposited at the junction angle was greater for pyroclastic sediment followed by weathered granite, weathered sedimentary rock, and finally, sand and shale. Our connectivity index suggests that a threshold exists between landslide dam formation and debris flow occurrence associated with topographic conditions, water content, and types of sediment.

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