Sediment yields and sources in a welsh upland lake‐catchment during the past 800 years
作者:
J. A. Dearing,
期刊:
Earth Surface Processes and Landforms
(WILEY Available online 1992)
卷期:
Volume 17,
issue 1
页码: 1-22
ISSN:0197-9337
年代: 1992
DOI:10.1002/esp.3290170102
出版商: John Wiley&Sons, Ltd
关键词: Lake‐catchment;Sediment yields;Sediment sources;Environmental magnetism;210Pb dating;N. Wales;Mining
数据来源: WILEY
摘要:
AbstractEstimates of suspended sediment yield over the past 800 years have been derived from a whole‐basin study of lake sediments in Llyn Geirionydd, North Wales. Magnetic and physical sediment properties were used to correlate a suite of cores to a master chronology based on210Pb and14C dates. The sources of sediment within the catchment were identified by comparing the magnetic and heavy metal properties of sediments, soils, and stream sediments. Mean suspended sediment yields range from 6 to 18 t km−2yr−1with high yields in the periods 1765‐1830 and 1903‐1985 corresponding to mining activities in the catchment. The impact of earlier deforestation, agricultural expansion, or climatic change on sediment yields is low, although there is evidence that agricultural activities increased levels of peak stream discharge. Afforestation in the 20th century does not appear to have significantly increased sediment yield. Sediment sources have remained fairly constant through time; they appear to be widespread and dominated by stream channel sides rather than point sources, except during the mining phases when spoil material has dominated the sediment load. Sediment loads to the lake today are still dominated by sediment derived from unvegetated sp
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