1. Deep, Semi-fossil Aquifers in Southern Africa:
From Occasional Findings Towards an Exploration Strategy
Prof. Dr. Thomas Himmelsbach Dr. Ralf Klingbeil
Federal Institute for Geosciences and Natural Resources (BGR), Germany Department Groundwater & Soil Sciences Stilleweg 2, Hannover, Germany Phone +49 (0) , Fax +49 (0)

2. Actual Catchment of Cuvelai-Basin
Etosha Pan: intra-continental endorheic basin
Tectonic subsidence since Cretaceous-Tertiary boundary
Increased sedimentation since 6 mio. years
Different lake levels can be delineated from ancient shore lines up to 1,100 m asl
Older and higher lake levels are questionable
Backward erosion truncated Kunene und Cubango from basin (35,000 a)
Cubango river feeds today together with Cuito river into Okavango Delta
… Etosha Salt Pan as final drainage level

3. Sedimentary Fans in the Cuvelai-Basin
Two prominent sedimentary magafans in Cuvelai-Basin
Represent deltaic sedimentation
Younger Cubango megafan buried older Kunene fan
Kunene megafan lies underneath Cubango megafan
Relevance for groundwater exploration
[source: Miller et al 2010]

4. Example for Delta Sedimentation (Areal Picture Okavango)
[Source:

5. Exploration for Ohangwena II Aquifer in Northern Namibia (Cuvelai-Etosha-Basin, Ohangwena)
TEM
Fluid Finder
Good agreement between geophysical soundings, drill core evaluation,
groundwater sampling (fluid finder) and hydrogeological modelling

6. TEM Profile (E–W) Parallel to Axis of Cuvelai-Basin

7. Groundwater Structure and Conditions Simplified Sketch
pan
hydraulic separating layer
local perched aquifers in un-saturated zone ?
extension, storativity and yield
precipitation 450 mm/a
high salinity aquifer
increasing salinity
recharge
discharge
180 – 240 m

8. Recharge Occurs in Angola
Satellite images indicate swampy areas during wet season
Swampy areas located in Angolan highlands, parallel to tectonic lineaments
Topography and geological maps indicate favourable infiltration conditions
Pilot study on Niipele-Odila catchment
before wet season
after wet season

9. Example Caprivi Strip and Okavango Delta

11. Climate Effects Combined with Tectonic Tilting and Distortion of Entire Southern African Basement - Recent Dry Areas
Chobe Swamps
Okavango Delta
Recent Magkadigkadi Pan
[Source:

12. Continuation of East African Rift Zone (EARZ)

13. Helicopter air borne geophysics (EM) along East Caprivi Graben Structure, upper Kalahari aquifer
strong indication of palaeo-channels with fresh groundwater
Linyanti Fault
[Source: Siemon, Roettger & Pielawa 2005 (BGR)]

14. X-Section B-B´ Okavango Delta
Schematic !
Vertically exaggerated
Modified after Meier 2008

15. Summary Recent findings of deep, freshwater aquifers often erratic
Exploration strategy needed, comparable to oil and gas exploration
Large intra-continental basins in Africa comprise today still hidden fossil or semi-fossil aquifers
Exploration requires: Investigating tectonic and sedimentary evolution, paleo-climate and hydrogeological conditions
Deep semi-fossil aquifers represent strategic resource for fast growing population and can contribute to climate change adaptation

16. TBA hotspots in the SADC region
What makes the topic you present a hotspot for TBA research? Regional relevance, basic hydrogeological understanding, similarity of TBAs
Looking at the topic you present: What are the most pressing issues in relation to: Regional research and transfer into common knowledge, reaching TB river and aquifer commissions
Looking at SADC region and all its known and still unmapped TBAs, what are the most pressing issues which need to be focused on in terms of: Regional coordination of research activities and assistance and knowledge transfer to local TBA institutions

17. Thank you very much for your attention!

18. Deep, Semi-fossil Aquifers in Southern Africa:
From Occasional Findings Towards an Exploration Strategy
Prof. Dr. Thomas Himmelsbach Dr. Ralf Klingbeil
Federal Institute for Geosciences and Natural Resources (BGR), Germany Department Groundwater & Soil Sciences Stilleweg 2, Hannover, Germany Phone +49 (0) , Fax +49 (0)