First Field Measurements of Sediment Transport Processes in the Middle Reaches of the Yarlung Zangbo River, on the High-Elevation Tibet Plateau

Increased knowledge of the processes which govern the transport of solids in sewers is necessary in order to develop more reliable and applicable sediment transport models for sewer systems. Proper validation of these are essential. For that purpose thorough field measurements are imperative. This paper renders initial results obtained in an ongoing case study of a Danish combined sewer system in Frejlev, a small town southwest of Aalborg, Denmark. Field data are presented concerning estimation of the sediment transport during dry weather. Finally, considerations on how to approach numerical modelling is made based on numerical simulations using MOUSE TRAP (DHI 1993).

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Sediment Transport and Water Flow Resistance in Alluvial River Channels: Modified Model of Transport of Non-Uniform Grain-Size Sediments

Water ◽

10.3390/w13152038 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2038

Author(s):

Gennady Gladkov ◽

Michał Habel ◽

Zygmunt Babiński ◽

Pakhom Belyakov

Keyword(s):

Sediment Transport ◽

Water Flow ◽

Transport Model ◽

Flow Characteristics ◽

Field Measurements ◽

Field Investigation ◽

Empirical Modeling ◽

River Channels ◽

Channel Deformations ◽

East European

The paper presents recommendations for using the results obtained in sediment transport simulation and modeling of channel deformations in rivers. This work relates to the issues of empirical modeling of the water flow characteristics in natural riverbeds with a movable bottom (alluvial channels) which are extremely complex. The study shows that in the simulation of sediment transport and calculation of channel deformations in the rivers, it is expedient to use the calculation dependences of Chézy’s coefficient for assessing the roughness of the bottom sediment mixture, or the dependences of the form based on the field investigation data. Three models are most commonly used and based on the original formulas of Meyer-Peter and Müller (1948), Einstein (1950) and van Rijn (1984). This work deals with assessing the hydraulic resistance of the channel and improving the river sediment transport model in a simulation of riverbed transformation on the basis of previous research to verify it based on 296 field measurements on the Central-East European lowland rivers. The performed test calculations show that the modified van Rijn formula gives the best results from all the considered variants.

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Combined Block Adjustment for Optical Satellite Stereo Imagery Assisted by Spaceborne SAR and Laser Altimetry Data

Remote Sensing ◽

10.3390/rs13163062 ◽

2021 ◽

Vol 13 (16) ◽

pp. 3062

Author(s):

Guo Zhang ◽

Boyang Jiang ◽

Taoyang Wang ◽

Yuanxin Ye ◽

Xin Li

Keyword(s):

Large Scale ◽

Satellite Image ◽

Field Measurements ◽

High Elevation ◽

Global Scale ◽

Stereo Image ◽

Image Process ◽

Control Points ◽

Altimetry Data ◽

Laser Altimetry

To ensure the accuracy of large-scale optical stereo image bundle block adjustment, it is necessary to provide well-distributed ground control points (GCPs) with high accuracy. However, it is difficult to acquire control points through field measurements outside the country. Considering the high planimetric accuracy of spaceborne synthetic aperture radar (SAR) images and the high elevation accuracy of satellite-based laser altimetry data, this paper proposes an adjustment method that combines both as control sources, which can be independent from GCPs. Firstly, the SAR digital orthophoto map (DOM)-based planar control points (PCPs) acquisition is realized by multimodal matching, then the laser altimetry data are filtered to obtain laser altimetry points (LAPs), and finally the optical stereo images’ combined adjustment is conducted. The experimental results of Ziyuan-3 (ZY-3) images prove that this method can achieve an accuracy of 7 m in plane and 3 m in elevation after adjustment without relying on GCPs, which lays the technical foundation for a global-scale satellite image process.

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