Channel response to gravel mining activities in mountain rivers
- 93 Downloads
The removal of bed material from active river channels usually affects the bed profile of the streambed, causing progressive degradation upstream and downstream of the extraction site. These effects can extend for kilometers affecting hydraulic structures located in the vicinity of the river reach. In this paper, the geomorphic effects of gravel mining are reviewed and summarized. Some cases in Venezuelan streams are presented to illustrate the problem. To describe the processes of erosion and sedimentation in a gravel extraction pit, a recent developed mathematical model for the simulation of flow and sediment transport in gravel-cobble bed streams is applied to a hypothetical case of gravel mining in a river channel. A simple rectangular dredge pit is imposed as initial condition in the channel bed, and changes in bed elevations and grain size distribution of bed material are calculated by using the numerical model. The process of deposition within the pit, and the downstream and upstream migration of the erosion wave are well simulated by the model and closely resemble the phenomena observed in laboratory experiments. The response of the friction coefficient to the changes in flow and bed elevations shows the importance in modeling adequately flow resistance and sediment transport in gravel-cobble bed streams.
KeywordsChannel response gravel mining Venezuelan cases
Unable to display preview. Download preview PDF.
- Aguirre Pe, J. and Fuentes, R. 1993. Stability and Weak Motion of Riprap at a Channel Bed. In: C. Thorneet al. (eds.),River, Coastal and Shoreline Protection. Erosion Control using Riprap and Armourstone. John Wiley & Sons Ltd.: 77–92.Google Scholar
- López, J.L. 1994. Problems caused by Gravel Extraction in the Tuy River Basin.Agency of the Tuy River Basin, Ministry of Environment, Internal Report (in Spanish), Caracas, Venezuela.Google Scholar
- Raynov, S., Pechinov, D., Kopaliany, Z. 1986. River Response to Hydraulic Structures.Technical Documents in Hydrology, Unesco, Paris.Google Scholar