Response of slope surface roughness to wave-induced erosion during water level fluctuating

• Published in: Journal of mountain science 2020-04, Vol.17 (4), p.871-883
• Main Authors: Gu, Ju, Liu, Gang, Abd Elbasit, Mohamed Ahmed Mohamed, Shi, Hong-qiang
• Format: Article
• Language: English
• Subjects: Bank erosion; Bulk density; Coefficient of variation; Earth and Environmental Science; Earth Sciences; Ecology; Elevation; Environment; Erosion rates; Geography; Knowledge management; Lakes; Mathematical analysis; Morphology; Reservoirs; River banks; Riverbanks; Rivers; Sediment; Soil erosion; Soil surfaces; Soils; Spatial variations; Steel structures; Surface roughness; Water level fluctuations; Water levels; Wld protein
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-019-5745-8

The bank slopes in hydro-fluctuation areas of reservoirs or lakes suffer from severe erosion due to an absence of protection. Waves are one of the important external forces that cause bank erosion and slope failures. However, the processes and quantified impacts of wave-induced erosion on slopes remain unclear under different water level-fluctuation conditions. This paper focuses on the characteristics of wave-induced slope erosion under three conditions: water level dropping (WLD), fixed (WLF) and rising (WLR). A steel tank with glass pane was used to simulate the wave-induced slope erosion in the three treatments. The slope elevation data were collected by using the method of the pin meter for every 15 minutes from the beginning to the end, a total of 5 times during all treatments. These data were processed by using software (SURFER 9.0) to get the slope micro-topography and the erosion volume. Then the temporal and spatial change of slope erosion was analysed according to the erosion amount or erosion rate calculated based on bulk density of slope soil. The results demonstrated that the soil erosion rates for different water level changing treatments are in the following order: WLR>WLD>WLF. For the erosion spatial variation, the middle part of the slope was the major source of sediment in the WLD. The upper part of the slope was the major source of the sediment for the other two treatments. Compared with the standard deviation (SD), the coefficient of variation (CV) based on the SD is more representative of variations in the soil surface roughness (SSR). Furthermore, the good fit between the SSR and soil erosion rate have the potential to be used to predict soil erosion. Above all, the injection angle of the wave determined the rate of erosion to some extent, and the fall-back flow of the wave could also influence the extent of erosion, deposition, and bank morphology. It is vital to choose the appropriate index (SD or CV) in the three water levels to improve the prediction accuracy. This paper could provide scientific knowledge to manage reservoirs or river banks.