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Mid to late Holocene geomorphological and sedimentological evolution of the fluvial-tidal zone: Lower Columbia River, WA/OR, USA

机译:河流潮汐区中期全新世纪中期地貌和沉积物演化:下哥伦比亚河,WA /或美国

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6.1 INTRODUCTION The majority of past oceanographic and sedimentological studies on the middle to late Holocene lower Columbia River (LCR) describe it as an estuary (e.g., Baker et al., 2010; Fox et al., 1984; Gelfenbaum, 1983; Hamilton, 1990; Hughes and Rattray, 1980; Jay, 1984; Jay and Smith, 1990; Jay et al., 1990; Peterson et al., 2012, 2013, 2014; Sherwood and Creager, 1990; Simenstad et al, 2011). This classification is based on the broad oceanographic definition proposed by Pritchard (1967), which defines an estuary as "a semi-enclosed coastal body of water in which the salinity is measurably diluted by fresh water derived from land drainage" (p. 3). Supporting evidence for this classification is found in the following present day LCR characteristics (Fig. 6.1B): (i) it lacks a distinct subaerial delta at its mouth, but does possess a subaqueous ebb-tidal delta seaward of its tidal inlet and an offshore ebb-tidal bar (Gelfenbaum et al., 1999, 2001; Kaminsky et al., 2010), (ii) the LCR possesses a relatively shallow, open-water, central bay that extends ~30 km upriver (A) 2009 aerial image of the lower Columbia River (LCR) with location map of the Columbia River drainage basin (inset), denoting prominent mid-channel bars/islands as well as the sedimentologically active Cathlamet Bay region and the off-axis back-bay regions of Grays and Youngs Bays, when the water surface elevation was below the Mean Lower-Low Water (MLLW) mark. (B) 2012 aerial image displaying the same location and characteristics as (A), but capturing the LCR when the water surface elevation was>MLLW, but
机译:6.1引进了大多数海洋摄影和沉积学研究中间到后期的中东地区哥伦比亚河(LCR)描述为河口(例如,Baker等,2010; Fox等,1984; Gelfenbaum,1983;汉密尔顿, 1990年;休斯和大鼠,1980; Jay,1984; Jay和Smith,1990; Jay等,1990; Peterson等,2014年,2012,2013,2014;谢尔伍德和克里克,1990; Simenstad等,2011)。该分类基于Pritchard(1967)提出的广泛海洋学定义,它将河口定义为“一个半封闭的沿海水体,其中盐度被源自陆地排水的淡水稀释”(第3页) 。在以下目前的LCR特征中发现了这种分类的支持证据(图6.1b):(i)它嘴里缺乏不同的骨髓三角洲,但确实具有其潮汐入口的亚水中的eBB-TIDAL DELTA。海上EBB-TIDAL BAR(GELFENBAUM等,1999,2001; Kaminsky等,2010),(ii)LCR拥有相对较浅的,开放的中央海湾,延伸〜30公里的Upriver(A)2009年下哥伦比亚河(LCR)的形象与哥伦比亚河排水盆(INSET)的定位图,表示突出的中间通道酒吧/岛屿以及沉积物主动的凯尔马特湾地区和灰色的轴外背湾地区和杨氏海湾,当水面高度低于平均低水平(MLLW)标记时。 (b)2012年空中图像显示与(a)相同的位置和特性,但是当水面升高> mllw时捕获LCR,但<平均海平面(MSL)。请注意,当水表面高度等于MSL时,所有开放的中间通道条都完全浸没。来自美国国家农业图像(Naip)的空中图像在https://gdg.sc.eg.usda.gov/。

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