Gravel Mining Activity Impact on Riverbed Erosion and Bridge Foundation Stability

Geomorphological processes pose a risk that deserves attention and planning to avoid that, especially in the section near to east of Tuz bridge. This section of the valley facing a dramatic increase in gravel excavation and sorting of aggregates, consequence led to a change in the pattern of river branches flow from an anabranching river to a single-channel river, which led to a concentration of river discharge during floods. On 9th December 2018, Tuz Bridge was failed due to a heavy rainstorm three days preceding the failure event. The current study aims to conduct a field survey of all the human activities in the study area to assess river changes from remote sensing data the amount of runoff and river peak discharge based on rainfall data using SCS-CN method. In this study, ArcGIS, ArcGIS Earth, Google Earth, and WMS software are incorporated in the data analysis. The revealed results indicate the severe modification of valley morphology and converting the river pattern to flow during flood within a single channel with flow speed exceeded the critical velocity to induce vertical erosion of gravel and sands under the foundations of the bridge and causing the displacement and settlement of the bridge. The study recommends the local administration prevent gravel mining from the river valley at the upstream area of the bridge

Anthropogenic impact and morphology channel response of Beskydian gravel-bed rivers: a case study of the Ostravice River, Czechia

This paper presents an analysis of both the contemporary and historic development of the geomorphic regime of the Ostravice River channel in the Czech part of the Outer Western Carpathians. The assessment concentrates on the conditions and causes of the channel development in the last 200 years compared with the state of European channels. The original anabranching river pattern has gradually been replaced by a single narrowed channel. At some sections, the original riverbed has lowered by as much as 2.5 m in the second half of the 20th century. These changes were due to strong anthropogenic impacts in the form of river-channel control and construction of dams. A large influence on the contemporary processes was also exerted by changed hydrological conditions and a predisposition of flysch lithology in a channel bedrock to erosion. Currently, the deficit of transportable sedimentary material along with the changed morphology of channels with concentrated water flows are intensifying erosion processes.