scholarly journals The Influence of Bed Roughness and Sediment Supply on Alluvial Cover in Bedrock Channels: Author Response

2020 ◽  
Author(s):  
Jagriti Mishra
Keyword(s):  
Sediment Supply ◽  
Author Response ◽  
Bed Roughness ◽  
Bedrock Channels

scholarly journals State of the Art Study of Influence of Bed Roughness and Alluvial Cover on Bedrock Channels and Comparisons of Existing Models with Laboratory Scale Experiments

2020 ◽  
Author(s):  
Jagriti Mishra ◽  
Takuya Inoue
Keyword(s):  
Mathematical Models ◽  
State Of The Art ◽  
Theoretical Models ◽  
Sediment Supply ◽  
Laboratory Scale ◽  
Experimental Results ◽  
Bed Topography ◽  
Bed Roughness ◽  
The Relationship ◽  
Bedrock Channels

Abstract. Several studies have implied towards the importance of bed roughness on alluvial cover, besides, several mathematical models have also been introduced to mimic the effect bed roughness may project on alluvial cover. Here, we provide a state of the art review of research exploring the relationship between alluvial cover, sediment supply and bed topography, thereby, describing various mathematical models used to analyse deposition of alluvium. In the interest of analysing the efficiency of various available mathematical models, we performed laboratory-scale experiments and compared the results with various models. Our experiments show that alluvial cover is not merely governed by increasing sediment supply, and, bed topography is an important controlling factor of alluvial cover. Testing experimental results with various theoretical models suggest a fit of certain models for a particular bed topography and inefficiency in predicting higher roughness topography. Three models efficiently predict the experimental observations, albeit their limitations which we discuss here in detail.

scholarly journals Alluvial cover on bedrock channels: applicability of existing models

2020 ◽  
Vol 8 (3) ◽  
pp. 695-716 ◽  
Author(s):  
Jagriti Mishra ◽  
Takuya Inoue
Keyword(s):  
Mathematical Models ◽  
Sediment Accumulation ◽  
Theoretical Models ◽  
Sediment Supply ◽  
Model Parameters ◽  
Hydraulic Roughness ◽  
Bed Topography ◽  
Bed Roughness ◽  
The Relationship ◽  
Bedrock Channels

Abstract. Several studies have demonstrated the importance of alluvial cover; furthermore, several mathematical models have also been introduced to predict the alluvial cover on bedrock channels. Here, we provide an extensive review of research exploring the relationship between alluvial cover, sediment supply and bed topography of bedrock channels, describing various mathematical models used to analyse the deposition of alluvium. To test one-dimensional theoretical models, we performed a series of laboratory-scale experiments with varying bed roughness under simple conditions without bar formation. Our experiments show that alluvial cover is not merely governed by increasing sediment supply and that bed roughness is an important controlling factor of alluvial cover. A comparison between the experimental results and the five theoretical models shows that (1) two simple models that calculate alluvial cover as a linear or exponential function of the ratio of the sediment supplied to the capacity of the channel produce good results for rough bedrock beds but not for smoother bedrock beds; (2) two roughness models which include changes in roughness with alluviation and a model including the probability of sediment accumulation can accurately predict alluvial cover in both rough and smooth beds; and (3), however, except for a model using the observed hydraulic roughness, it is necessary to adjust model parameters even in a straight channel without bars.

Coarse sediment supply sets the slope of bedrock channels in rapidly uplifting terrain: Field and topographic evidence from eastern Taiwan

2021 ◽  
Author(s):  
Larry Syu‐Heng Lai ◽  
Joshua J. Roering ◽  
Noah J. Finnegan ◽  
Rebecca J. Dorsey ◽  
Jiun‐Yee Yen
Keyword(s):  
Sediment Supply ◽  
Coarse Sediment ◽  
Bedrock Channels

scholarly journals Conversion of tectonic and climatic forcings into records of sediment supply and provenance

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Glenn R. Sharman ◽  
Zoltan Sylvester ◽  
Jacob A. Covault
Keyword(s):  
Sediment Load ◽  
Sediment Supply ◽  
Sediment Provenance ◽  
Sediment Sources ◽  
Environmental Forcing ◽  
Stratigraphic Record ◽  
Forcing Mechanisms ◽  
Bedrock Channels ◽  
Geomorphic Processes ◽  
Different Time Scales

Abstract Understanding how environmental forcings (e.g., tectonics, climate) are transformed by erosional landscapes into sedimentary signals is a critical component of inverting the stratigraphic record. Previous research has largely focused on sediment supply (Qs) and grain size as the de facto sedimentary signals of changing forcing mechanisms. We use a numerical model to consider the paired response of sediment provenance (Pv), expressed as fractional sediment load, and Qs to demonstrate that the same change in environmental forcing may have a different expression in the sedimentary record. While Qs reflects integrated denudation across an erosional catchment, Pv is controlled by spatially variable erosion that occurs in transient landscapes. Pv from proximal sediment sources increases during upstream knickpoint migration, whereas Pv from distal sediment sources increases when bedrock channels incise to produce lower gradient profiles. Differences between the Qs and Pv signals relate to distinct geomorphic processes that operate on different time scales and allow for a refined differentiation of the timing and mechanism of forcings than possible via analysis of either signal alone. Future efforts to integrate multiple sedimentary signals may thus yield a richer picture of underlying forcing mechanisms, facilitating efforts to invert the stratigraphic record.

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