Search

More information: https://academicworks.cuny.edu/cc_conf_hic/276/

Integrated Modeling of Hydro-Systems

Sediment Transport and Morphodynamics

Bislang ist die Theorie der Böschungsbruchvorgänge für kohäsionslosen Boden auf ebenen Gleitfugen in einem rollenden, nicht verdichteten und voll gesättigten Boden mit diskreten Körnern begrenzt und damit vor allem für Kiesboden anwendbar. Die vorliegende Felduntersuchung hat aber gezeigt, dass Unterspülung und Gleitfugen unterhalb des Wasserspiegels sowie Abbruch der Überhänge die dominanten Prozesse im kohäsionslosen verdichteten (sandigen) Boden unter instationären Bedingungen sind. Diese Prozesse wurden in der vorliegenden Arbeit durch eine innovative Methode modelliert, die durch Feldmessungen validiert wurde. Die Ergebnisse zeigten, dass diese Methode die Genauigkeit der Simulation im Vergleich zu den bisherigen Methoden bis zu sechsmal verbessert., So far the theory of bank failure in non-cohesive soils is limited to the avalanche of loose, not compacted, fully saturated discrete grains, applicable mainly to gravel banks. However, the present field investigation indicated that undercutting of the riverbank, slip failure of the submerged zone of the bank, as well as cantilever failure of the overhang are the dominant processes in non-cohesive dense (sandy) soils under unsteady flow conditions. These processes have been modelled in the present work by an innovative method, which has been validated by field measurements. The results showed that the method enhanced the simulation accuracy up to six times in comparison to the earlier methods.

River morphodynamics and sediment transport Bank erosion and protection

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

The paper aims at studying the effect of difference in bed elevations between the tributary and main canals (∆zT) on the flow in the confluence hydrodynamics zone. To do this, a 3D numerical model is used for flow simulation at 90 confluences with four different values of the ∆zT/h ratio (where h is the water depth in the main canal at the confluence). The values are in the range [0.0, 0.5]. The ∆zT /h = 0.00 case corresponds to the concordant beds confluence, and the value of 0.50 is the common value in field confluences. Special attention is paid to the flow deflection and recirculation zones. It is found that: 1) the vertical velocity component attains the same order of magnitude as the horizontal velocity with the increasing ∆zT , 2) the enhanced 3D flow close to the side-wall shifts the recirculation zone away from the wall to the boundary streamline, thus changing the recirculation zone orientation whose axis becomes inclined at an angle to the wall, 3) the size of the zone is reduced and 4) the structure of the zone is completely destroyed close to the free surface, where the core of the w_max is located.