scholarly journals Seasonal vegetation and management influence overland flow velocity and roughness in upland grasslands

2020 ◽  
Vol 34 (18) ◽  
pp. 3777-3791
Author(s):  
Stephanie Bond ◽  
Mike J. Kirkby ◽  
Jean Johnston ◽  
Alistair Crowle ◽  
Joseph Holden
Keyword(s):  
Flow Velocity ◽  
Overland Flow

Experimental study of sediment transport processes and size selectivity of eroded sediment on steep Pisha sandstone slopes

2020 ◽  
Author(s):  
Pan Zhang ◽  
Pingqing Xiao ◽  
Chunxia Yang
Keyword(s):  
Sediment Transport ◽  
Flow Velocity ◽  
Overland Flow ◽  
Yellow River ◽  
Transport Processes ◽  
The Yellow River ◽  
Size Selectivity ◽  
Coarse Sediment ◽  
Sediment Particles ◽  
Slope Flow

<p>The Pisha sandstone area on the Ordos Plateau of China is the primary source of coarse sediment of the Yellow River. Sediment size distribution and selectivity greatly affect sediment transport and deposition. Hence, sediment transport processes and size selectivity by overland flow on Pisha sandstone slopes were investigated in this study. Experiments were run with Pisha sandstone soil (bulk density of 1.35 g/cm<sup>3</sup>) under rainfall intensities of 87 and 133 mm/h with a 25° slope gradient, and the duration of simulated rainfall is 1 h. Sediment and runoff were sampled at 2-min intervals to examine the size distribution change of the eroded sediment. The particle composition, enrichment rate, fractal dimension, and time distribution characteristics of median grain size (d<sub>50</sub>) of eroded sediment were comprehensively analyzed. Statistical analyses showed that the erosion process of Pisha sandstone slope mainly transported coarse sediment. More than 40% of eroded sediment particles were coarse sediment, which will become the main sediment in the lower reaches of the Yellow River bed. The particle size of eroded sediment tended to gradually decrease with the continuous rainfall but remained larger than the background value of Pisha sandstone soil after refinement. The fractal dimension was positively correlated with the slope flow velocity, while the d<sub>50</sub> was negatively correlated with the slope flow velocity. Overall, these findings show a strong relationship between the sediment transport and flow velocity, which indicates that the selectivity and transportation of sediment particles on the Pisha sand slopes is mainly influenced by the hydrodynamic parameters of overland flow. This study provides a methodology and data references for studying the particle selectivity characteristics of eroded sediment and provides a scientific basis for revealing the mechanism of erosion and sediment yield in the Pisha sandstone area of China.</p>

scholarly journals Overland flow velocity and roughness properties in peatlands

2008 ◽  
Vol 44 (6) ◽  
Author(s):  
Joseph Holden ◽  
Mike J. Kirkby ◽  
Stuart N. Lane ◽  
David G. Milledge ◽  
Chris J. Brookes ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Overland Flow

scholarly journals Using thermal tracers to estimate flow velocities of shallow flows: laboratory and field experiments

2015 ◽  
Vol 63 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Rui L.P. de Lima ◽  
João R.C.B. Abrantes ◽  
João L.M.P. de Lima ◽  
M. Isabel P. de Lima
Keyword(s):  
Flow Velocity ◽  
Field Experiments ◽  
Overland Flow ◽  
Velocity Estimation ◽  
Shallow Flow ◽  
Shallow Flows ◽  
Dye Tracer ◽  
Flow Surface ◽  
Infrared Technology ◽  
Hydrology And Water Resources

Abstract Accurate measurement of shallow flows is important for hydraulics, hydrology and water resources management. The objective of this paper is to discuss a technique for shallow flow and overland flow velocity estimation that uses infrared thermography. Laboratory flumes and different bare, vegetated and paved field surfaces were used to test the technique. Results show that shallow flow surface velocities estimated using thermal tracers and infrared technology are similar to estimates obtained using the Acoustic Doppler Velocimeter; similar results were also obtained for overland flow velocity estimates using thermography, here comparing with the dye tracer technique. The thermographic approach revealed some potential as a flow visualization technique, and leaves space for future studies and research.

Effect of flow discharge and median grain size on mean flow velocity under overland flow

2012 ◽  
Vol 452-453 ◽  
pp. 150-160 ◽  
Author(s):  
M. Ali ◽  
G. Sterk ◽  
M. Seeger ◽  
L. Stroosnijder
Keyword(s):  
Grain Size ◽  
Flow Velocity ◽  
Overland Flow ◽  
Mean Flow ◽  
Flow Discharge ◽  
Mean Flow Velocity

scholarly journals A data-driven method for the determination of water-flow velocity in watershed modelling

2018 ◽  
Author(s):  
Qiming Zhou ◽  
Fangli Zhang ◽  
Liang Cheng
Keyword(s):  
Spatial Distribution ◽  
Flow Velocity ◽  
Water Flow ◽  
Hydrological Modeling ◽  
Overland Flow ◽  
Data Driven ◽  
Terrain Analysis ◽  
Hydrological Models ◽  
Water Flow Velocity ◽  
Water Transportation

Physically-based distributed hydrological models have always played an important role in watershed hydrology. Existing hydrological modeling applications focused more on the estimation of water balance and less on the simulation of water transportation in a catchment. Different from the prediction of flow production, the dynamic simulation of flow concentration depends largely on the field distribution of water-flow velocity. However, it is still difficult to determine the water-flow velocity with terrain analysis techniques, which had always hampered the application of hydrological models in surface water transportation simulation. This study, therefore, proposes a data-driven method for creating a field map of overland flow velocity based on the Manning’s equation. Case study on a gauged watershed is undertaken to validate the spatial distribution of flow velocity. The preliminary results indicate that the proposed empirical method can reasonably determine the spatial distribution of water-flow velocity. Further efforts are still required to support the space-time change of flow velocity under the control of microtopography and instantaneous water depth.

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