Knowledge Resource Center for Ecological Environment in Arid Area
| DOI | 10.1002/esp.5289 |
| Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana | |
| Tooth, Stephen; McCarthy, Terence S.; Duller, Geoff A. T.; Assine, Mario L.; Wolski, Piotr; Coetzee, Grace | |
| Corresponding Author | Tooth, S |
| Journal | EARTH SURFACE PROCESSES AND LANDFORMS
 |
| ISSN | 0197-9337 |
| EISSN | 1096-9837 |
| Year Published | 2022 |
| Abstract in English | Information on past dryland environments is commonly derived from geomorphological landforms and sediments ('geoproxies'). The Okavango Delta in the middle Kalahari, Botswana, has been subject to a long history of arid-humid transitions but its potentially rich archive of fluvial geoproxies is largely untapped. Previous palaeoenvironmental studies in the Delta region have focused mainly on aeolian dunes, lacustrine beach ridges, and rare pollen sequences in surrounding locations, and the Delta's channel dynamics have remained poorly constrained, both chronologically and in quantitative palaeohydrological terms. Focusing on the Delta's Xugana region, we present the first optically stimulated luminescence ages for palaeochannel fills and scroll bars, revealing significantly enhanced fluvial activity in the similar to 7-4 ka interval. Along 120-150 m-wide, sand-bed, sinuous palaeochannels, lateral migration and bend cutoffs were driven by palaeodischarges up to similar to 350-450 m(3) s(-1), at least nine times those of the present-day channels. These palaeochannels represent the last major phase of meander activity in the middle and lower Delta. The palaeodischarges imply significantly higher rainfall over the catchment in the mid Holocene, possibly resulting from a southwards shift of the African tropical rainbelt. Over the last few thousand years, diminished fluvial activity in the Xugana region has continued; <20 m-wide channels with discharges typically <40 m(3) s(-1) have been more laterally stable, albeit subject to local avulsions. These findings provide the 'missing link' between evidence for past intervals of enhanced rainfall in the Delta's tributary catchments in the northwest and west and the filling of large lacustrine basins to the southeast and east. The findings contribute to improved understanding of changing Kalahari hydroclimates and support growing evidence indicating that the mid to late Holocene was a time of significant fluvial transformation across many of the world's drylands. |
| Keyword in English | Holocene climate Kalahari luminescence dating Okavango Delta palaeodischarge scroll bar |
| Subtype | Article ; Early Access |
| Language | 英语 |
| OA Type | Green Submitted |
| Indexed By | SCI-E |
| WOS ID | WOS:000739613900001 |
| WOS Keyword | PALAEO-ENVIRONMENTAL CHANGE ; CENTRAL SOUTHERN AFRICA ; LATE QUATERNARY ; LAKE NGAMI ; KALAHARI DESERT ; CLIMATE-CHANGE ; MEGA-LAKE ; LUMINESCENCE ; RIVER ; DYNAMICS |
| WOS Subject | Geography, Physical ; Geosciences, Multidisciplinary |
| WOS Research Area | Physical Geography ; Geology |
| Document Type | 期刊论文 |
| Identifier | http://119.78.100.177/qdio/handle/2XILL650/377178 |
| Recommended Citation GB/T 7714 | Tooth, Stephen,McCarthy, Terence S.,Duller, Geoff A. T.,et al. Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana[J],2022. |
| APA | Tooth, Stephen,McCarthy, Terence S.,Duller, Geoff A. T.,Assine, Mario L.,Wolski, Piotr,&Coetzee, Grace.(2022).Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana.EARTH SURFACE PROCESSES AND LANDFORMS. |
| MLA | Tooth, Stephen,et al."Significantly enhanced mid Holocene fluvial activity in a globally important, arid-zone wetland: The Okavango Delta, Botswana".EARTH SURFACE PROCESSES AND LANDFORMS (2022). |
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