Fjölrit RALA - 05.12.1999, Síða 65

MlTCHAEL B.K. DARKOH
63
evaporation is generally high.
Daily rates of open-water
evaporation may reach 7.5 mm.
Drought is endemic and tends
to occur with a quasi 10-12
year periodicity.
In view of the frequency of
drought and the paucity of sur-
face water in the country,
groundwater assumes a special
importance. About 75% of the
country’s human and animal
population are dependent on it
(Cooke 1983). It is estimated
that groundwater has an ex-
tractable volume of 100,000
million cubic metres with only
1% rechargeable by rainfall
(Khupe 1994). Access to
groundwater has been made
possible by modern technology of water prospecting and deep borehole drilling. Thus,
it is only recently with its availability in the country that groundwater has assumed
major significance as a key resource. It has made possible, as we shall later observe, a
significant shift in the direction of grazing pressure.
Another effect of the endemic drought and surface water scarcity is the limited po-
tential of the greater part of the territory for settled agriculture. In fact, less than five
per cent of the country is suitable for rain-fed agriculture. Farming activities entail
mixed cultivation in addition to cattle and smallstock grazing which extends from the
outskirts of towns and villages (Ringrose et al. 1997). In the remaining 95% of the
country, livestock raising is the main economic activity. Most of the land (71%) is un-
der communal or tribal grazing tenure, 23% is Stateland, while a small proportion
(6%) is freehold lease for large-scale commercial ranching. Over 50% of all house-
holds in Botswana own cattle, which is presently the largest single source of rural in-
come. However, this percentage is slowly declining (Amtzen et al. 1994, 1996).
In the rangelands which cover 95% of the country, a number of land use categories
can be identified. These include village-based communal grazing and borehole-based
cattleposts which are owned by individuals or syndicates. In both cases, livestock
graze freely in the available range and often retum to the kraal for watering at night.
The third category is freehold govemment leased ranches which are fenced and under
individual management. The country’s rangelands also include extensive areas of Na-
tional Parks and Game Reserves (18% of the surface area of Botswana) which are
coming under increasing pressure because of conflicting land uses.
Figure 3. Rainfail distribution and reliability.