Inherited drainage - paleochannels and preferential groundwater flow
Författare
Summary, in English
It is suggested that in a localized remnant of Kalahari sand at Dufuya, central Zimbabwe, groundwater flows in an integrated pattern inherited from the paleochannel network of the underlying gneiss. Contact springs occur at discrete localities along the Kalahari sand/gneiss boundary and are associated with spring sapping and land surface subsidence. Subsidence is presumed to be due to preferential solute removal by leaching and dissolution as a result of concentration of groundwater flow within the buried paleochannel network and the location of the springs is presumed to occur where the paleochannel network intersects the Kalahari sand/gneiss boundary. Over time the surficial Kalahari sand is preferentially removed along these buried drainage lines by spring sapping and headwards erosion, exposing the gneiss. Multi-electrode direct current resistivity profiling and radar have been used to map the sub-surface, revealing the topography of the basement and nature of the Kalahari cover. Coincidence of gneiss basement depressions with the spring sites, leached sands and subsidence zones suggests inheritance of the gneiss fluvial paleochannel network pattern by the present day groundwater flow. Washed sand and gravel intersected in shallow boreholes in these areas provides further evidentiary support for the concept of inherited drainage.
Avdelning/ar
Publiceringsår
2010
Språk
Engelska
Sidor
893-903
Publikation/Tidskrift/Serie
Hydrogeology Journal
Volym
18
Issue
4
Fulltext
- Available as PDF - 939 kB
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Dokumenttyp
Artikel i tidskrift
Förlag
Springer
Ämne
- Geotechnical Engineering
Nyckelord
- Geophysical methods
- Inherited drainage
- Preferential groundwater flow
- Kalahari
- Zimbabwe
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 1431-2174