کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6431776 | 1635399 | 2015 | 10 صفحه PDF | دانلود رایگان |
- Unique 3-year record of sediment detached from the crests of an arid granitic range.
- Grus detachment in a few extreme events is more than all other rains combined.
- Detached amount increases with steeper slopes, larger drainages and more exposed soil.
- Suspended sediment derives from recycled eolian dust deposited on crests.
Quantifying erosion rates in different landscape settings provides insight into how landforms change under different climatic, tectonic and anthropogenic influences. Sediment traps designed to capture grus detached from granitic hill crests of an arid Sonoran Desert mountain range were placed prior to every precipitation event over a three-year period, just above rills that drain areas between 18 and 68Â m2. The slopes are underlain by moderately to strongly weathered granitic rocks to a depth of about a meter. Within this 3-year window, a 1000-year precipitation event followed 27Â days later by a 500-year event detached granitic grus in amounts far greater than previous storms, capturing between 22Â Ã and 63Â Ã the average amount transported in the previous 59 rain events - indicating the non-linear nature of the response of grus detachment to precipitation intensity. Considering every precipitation event over a 3-year period, no detachment occurred from events with less than 2Â mm of total rainfall, and only minimal erosion occurred from rainfall events with totals between 2 and 10Â mm with durations typically less than 30Â min. Detachment increased greatly with rain intensities of 36Â mm/h or more. Grus detachment from these arid crests increases with drainage area, a higher percentage of exposed soil, and steeper slopes. 87Sr/86Sr ratios reveal that suspended sediment transported from hill crest to trap derives from recycled dust and not the local granite bedrock.
Journal: Geomorphology - Volume 250, 1 December 2015, Pages 53-62