대표연구 논문 실적
Gravel bar shielding: A mechanism responsible for bar stabilityin gravel- and cobble-bedded streams
발행년도
20250605
저자
Ariel do Prado, Cristiano Padalino Galeazzi, David Mair, Philippos Garefalakis, Renato Paes de Almeida, Alexander C. Whittaker, Fritz Schlunegger
저널
EARTH SURFACE PROCESSES AND LANDFORMS
작성자
전지현
작성일
2025-07-01
조회
22
Abstract
The stability of gravel bars and riverbanks is often attributed to the presence of vege-tation, yet the conditions controlling the stability of such bars without of a vegetationcover have remained unclear. Here, we propose that such controls are exerted bywhat we refer to as ‘lateral lag deposits’, which result from the winnowing of gravelbar edges during periods when channels widen. We base this interpretation on anexample from the Sense River, Switzerland, a natural wandering-braided stream withgravel-cobble bars devoid of vegetation. Through a survey where we measured thesize of several thousands of grains along two up to 50 m-long reaches, we found thatthe 84th percentile values (D 84) of the grain size distributions (GSD) are consistentlylarger on the eroded bar edges compared to the bar top or the channel between bars.At these bar edges, the coarse grains appear to shield the gravel bar from lateral ero-sion, thus forming a lag deposit. Orthoimages taken along the studied reachesbetween 2017 and 2023 reveal that the target lateral lag deposits outlasted severallower-discharge floods, during which the sedimentological architecture of the investi-gated reach changed multiple times. We therefore suggest that lateral lag depositsare among the sedimentological structures of braided streams with the highest pres-ervation potential and that they exert the largest threshold to the completereworking of gravel bars without vegetation
http://dx.doi.org/10.1002/esp.70107
The stability of gravel bars and riverbanks is often attributed to the presence of vege-tation, yet the conditions controlling the stability of such bars without of a vegetationcover have remained unclear. Here, we propose that such controls are exerted bywhat we refer to as ‘lateral lag deposits’, which result from the winnowing of gravelbar edges during periods when channels widen. We base this interpretation on anexample from the Sense River, Switzerland, a natural wandering-braided stream withgravel-cobble bars devoid of vegetation. Through a survey where we measured thesize of several thousands of grains along two up to 50 m-long reaches, we found thatthe 84th percentile values (D 84) of the grain size distributions (GSD) are consistentlylarger on the eroded bar edges compared to the bar top or the channel between bars.At these bar edges, the coarse grains appear to shield the gravel bar from lateral ero-sion, thus forming a lag deposit. Orthoimages taken along the studied reachesbetween 2017 and 2023 reveal that the target lateral lag deposits outlasted severallower-discharge floods, during which the sedimentological architecture of the investi-gated reach changed multiple times. We therefore suggest that lateral lag depositsare among the sedimentological structures of braided streams with the highest pres-ervation potential and that they exert the largest threshold to the completereworking of gravel bars without vegetation
http://dx.doi.org/10.1002/esp.70107
