Premium
Channels, wetlands and islands in the Okavango Delta, Botswana, and their relation to hydrological and sedimentological processes
Author(s) -
Gumbricht T.,
McCarthy J.,
McCarthy T. S.
Publication year - 2004
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.1008
Subject(s) - delta , wetland , clastic rock , sedimentation , geology , river delta , channel (broadcasting) , physical geography , hydrology (agriculture) , geography , geomorphology , sediment , paleontology , ecology , sedimentary rock , electrical engineering , geotechnical engineering , engineering , biology , aerospace engineering
The Okavango wetland in northern Botswana is one of the world's largest inland deltas. The delta is a dynamic environment with shifting channel routes, causing growth and decay of anking wetlands, and giving birth to islands. Primary island nuclei are formed by uvial processes and bioengineering, and subsequently grow into secondary larger islands of irregular shape by clastic and chemical sedimentation, and later by coalescence. This article presents classications and quantitative estimations of channels, wetlands and islands of the Okavango Delta. Islands were classied dependent on composition, pattern of composition, shape and juxtaposition. 90 per cent of all islands in the entire wetland were identied, with a classication accuracy of 60 to 85 per cent. Smaller islands of the nucleus types dominate the upper parts of the delta, whereas larger secondary islands are more common in the distal part, a reection of the age of the islands. Islands in the entry valley of the delta, the Panhandle, are larger in the top end – the primary region of recent clastic sedimentation. The overall size distribution of islands in the delta, however, shows no clumps, indicating that island growth is a uniform process over time and space. The total area ooded at least every decade is approximately 14 000 km 2 , of which 9000 km 2 is classied as actual wetland. Channel meandering decreases from the Panhandle to the distal part of the delta, with the abandoned Thaoge channel as an exception. Occurrence of uvially formed islands in the distal delta indicates that the water ow and area of inundation must once have been much larger. Copyright © 2004 John Wiley & Sons, Ltd.