Okavango Delta Management Plan - Ramsar Convention on Wetlands

which is itself an extension of the East African Rift system. The significance of the rift lies
in the fact that this fault system is presently active and may well lead to renewed
earthquake activity in the foreseeable future. The most noteworthy faults are Gumare,
Kunyere and Thamalakane.
The overlying Kalahari Group sediments contain some calcretes and silicretes which occur
as a result of strong evaporation following past or present hydrological processes. Calcretes
and silcretes (duricrusts) are used along with crushed bedrock throughout the <strong>Ramsar</strong> site
for road construction and maintenance.
2.2.5 HYDROGEOLOGY
Three major aquifer formations exist in the ODRS. These are the Basement rocks, Karoo
and Kalahari Group sediments. Karoo and Basement rocks, where they occur at shallow
depth, also form locally important aquifers. The Kalahari Group sediments comprise the
most important known aquifers. These aquifers are at shallow depth, typically less than
100 m. Although at places several distinct aquifers can be distinguished within the
Kalahari Group profile, they are usually hydraulically connected. The groundwater table is
present at 5-30 m below ground in non-floodable areas, and is shallower (typically 0-10 m)
within contemporary and recently flooded floodplains.
Figure 2-5: Geological map of the ODRS
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