Duration and severity of Medieval drought in the Lake Tahoe Basin

QUATERNARY SCIENCE REVIEWS

卷:30

Article

Kleppe, J. A.²  Brothers, D. S.¹  Kent, G. M.³  Biondi, F.⁴  Jensen, S.⁵  Driscoll, N. W.⁶ 

[1] US Geol Survey, Woods Hole Coastal & Marine Sci Ctr, Woods Hole, MA 02543 USA

[2] Univ Nevada, Coll Engn, Reno, NV 89557 USA

[3] Univ Nevada, Seismol Lab, Reno, NV 89557 USA

[4] Univ Nevada, DendroLab, Reno, NV 89557 USA

[5] Northwestern Univ, Dept Earth & Planetary Sci, Evanston, IL 60208 USA

[6] Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA

关键词: Medieval climatic anomaly;    Sidescan sonar;    Holocene;    Dendrochronology;    Drought;    Fallen Leaf Lake;   

DOI  :  10.1016/j.quascirev.2011.08.015

来源: Elsevier

【 摘 要 】

Droughts in the western U.S. in the past 200 years are small compared to several megadroughts that occurred during Medieval times. We reconstruct duration and magnitude of extreme droughts in the northern Sierra Nevada from hydroclimatic conditions in Fallen Leaf Lake, California. Stands of submerged trees rooted in situ below the lake surface were imaged with sidescan sonar and radiocarbon analysis yields an age estimate of similar to 1250 AD. Tree-ring records and submerged paleoshoreline geomorphology suggest a Medieval low-stand of Fallen Leaf Lake lasted more than 220 years. Over eighty more trees were found lying on the lake floor at various elevations above the paleoshoreline. Water-balance calculations suggest annual precipitation was less than 60% normal from late 10th century to early 13th century AD. Hence, the lake's shoreline dropped 40-60 m below its modern elevation. Stands of pre-Medieval trees in this lake and in Lake Tahoe suggest the region experienced severe drought at least every 650-1150 years during the mid- and late-Holocene. These observations quantify paleo-precipitation and recurrence of prolonged drought in the northern Sierra Nevada. Published by Elsevier Ltd.

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