Groundwater in Namibia - an Explanation to the ... - BGR
Groundwater in Namibia - an Explanation to the ... - BGR
Groundwater in Namibia - an Explanation to the ... - BGR
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The pr<strong>in</strong>cipal aquifer formations of <strong>Namibia</strong> <strong>an</strong>d <strong>the</strong>ir representation on <strong>the</strong> Hydrogeological Map<br />
water <strong>to</strong> meet <strong>the</strong> required dem<strong>an</strong>d.<br />
Certa<strong>in</strong> favourable geological features enh<strong>an</strong>ce <strong>the</strong> use<br />
of aquifers with low perm eability. When fault zones or valleys<br />
follow<strong>in</strong>g zones of crustal weakness cut through aquifers<br />
with low permeability, <strong>the</strong> water collects over a large area<br />
<strong>an</strong>d c<strong>an</strong> be abstracted at <strong>an</strong> exceptionally high rate by boreholes<br />
drilled <strong>in</strong><strong>to</strong> <strong>the</strong>se favourable water collect<strong>in</strong>g structures.<br />
As shown <strong>in</strong> <strong>the</strong> map above, <strong>the</strong> follow<strong>in</strong>g types of aquifers<br />
are widespread <strong>in</strong> <strong>Namibia</strong>:<br />
• Porous aquifers<br />
Source: HYMNAM Project<br />
© GSN, DWA<br />
• Fractured aquifers<br />
• Aquitards or aquicludes<br />
The rate at which groundwater c<strong>an</strong> be abstracted from <strong>an</strong><br />
aquifer is determ<strong>in</strong>ed by <strong>the</strong> porosity <strong>an</strong>d <strong>the</strong> permeability.<br />
The qu<strong>an</strong>tity of groundwater that c<strong>an</strong> be abstracted over time<br />
is determ<strong>in</strong>ed by <strong>the</strong> rate at which <strong>the</strong> water c<strong>an</strong> be abstracted<br />
<strong>an</strong>d <strong>the</strong> volume of water that is available for abstraction is determ<strong>in</strong>ed<br />
by <strong>the</strong> s<strong>to</strong>rage capacity of <strong>the</strong> aquifer. The long-term susta<strong>in</strong>able<br />
safe yield from <strong>an</strong> aquifer also depends on <strong>the</strong> recharge<br />
of <strong>the</strong> water abstracted or discharged from <strong>an</strong> aquifer.<br />
From this it is clear that a number of hydrogeological<br />
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