کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6432715 1635445 2014 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Late Holocene chronology and geomorphic development of fluvial-tidal floodplains in the upper reaches of the lower Columbia River Valley, Washington and Oregon, USA
ترجمه فارسی عنوان
تاریخچه قرن بیست و یکم هولوکسی و توسعه ژئومورفیک از سیلابهای رودخانه ای در بالادست دره رودخانه کلمبیا، واشنگتن و اورگان، ایالات متحده آمریکا
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
چکیده انگلیسی

The upper reaches of the lower Columbia River Valley (125 km in length) comprise an alluvial system that is transitional between fluvial and fluvial-tidal dominance. Sinuous channels separate elongate islands (1-8 km in length) and floodplains (0.5-12.7 km in total width). Thirty-six floodplain overbank deposits are analyzed for age and depth, which demonstrate an average sedimentation rate of 1.6 m ka− 1 during the last 5-6 ka. Older core records confirm that long-term depositional rates are controlled by relative sea level rise. Rising floodplain groundwater surfaces, which followed relative sea level rise (~ 1.25 m ka− 1), submerged isolated floodplain depressions. Low sedimentation rates in the isolated depressions (0.6-1.1 m ka− 1) maintained large ellipsoidal bullseye lakes (7-22 km2 in area) dating back to 3.5-4.0 ka. Increases in the widths of the floodplains and bullseye lakes are associated with broadening of the incised valley (4-13 km width) in the Portland Basin. Dated basal overbank deposits (0.5-5.0 ka in age) and their separation distances establish channel migration rates of 0.3-1.9 km ka− 1. Shallow burial rates relative to rapid channel migration rates resulted in reworking of late Holocene floodplains (50-75% erosion) since 5 ka in the upper reaches of the lower Columbia River Valley.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geomorphology - Volume 204, 1 January 2014, Pages 123-135
نویسندگان
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