botswana/namibia - Cour international de Justice

G28 - 1947 aerial photograph with labels
G29 - 1962 aerial photograph with labels
[9. Attention should, however, be drawn to a possible alternative interpretation of the May 1972 photograph
namely that the southern channel is choked by a mat of Salvinia Molesta (Kariba weed). The Chobe/Linyanti
system was known to have localised infestations of Salvinia at this time. However, it is not thought to have
existed in the southern channel in May 1972 for the following reasons:-
(i) Salvinia is a total infestation taking the form of an all-covering densely packed mat, which when established,
can support a secondary growth of shrubs, grasses and other plants on its surface. The large open pool just
opposite the Headquarters of the Chobe National Park is therefore completely uncharacteristic of a typical
Salvinia infestation.
(ii) Salvinia infestation is a very long lasting problem and can subsist for many years, yet in the November 1972
photograph discussed below, which was taken only a few months later, there is no sign of the mat at all.
(iii) The flow chart for the Zambezi given as table 1 on page 15 of the Expert Report, (Namibian Memorial,
Vol.VI, part 1), shows that in 1972, the average flow of the Zambezi was at 640 cubic metres per second, the
lowest flow since 1948 and also the 6th lowest since 1900. It is obvious that the volume of flow in the Zambezi
was too low to push through the Kasai channel and back up the Chobe River as is normal when the average flow
is around 1500 cubic metres per second.
For the foregoing reasons, it is submitted that the correct interpretation of the May 1972 photograph is that it
shows the southern channel to be dry for half its length.
In any event, the Botswana case would still be assisted by this photograph, as Salvinia is normally associated
with backwaters, very slow moving streams and inlets. As the northern and western channels are completely
clear, it follows that the current running through these channels has prevented the spread of the weed, unlike the
southern channel.]
413. Most of the southern section of the Spur channel is also dried out indicating a very low
water level. This photograph provides strong confirmation that the southern channel is only a
seasonal backwater of the Chobe River, reduced to a trickle or drying out in a dry season.
The November 1972 Photograph (Scale 1:10,000 approx.) Average mean flow 640m3.
(1972). Reproduced with labels at page 175.
414. This photograph is particularly valuable as a record of the actual manner in which the
flood waters of the Zambezi enter the Chobe system. Contrary to Professor Alexander's
assertions, there is no flood path across the flood plain but a channelled back flow through the
cross-channels linking the Chobe with the Zambezi River. In the five months between the
May and November photographs, the rising waters in the river north of the Island, caused by
flood-water run-off from the Zambezi, have pushed upstream into the southern channel to link
up with the western sector of the northern channel at the bifurcation zone marked B.
However, the channel is barely visible on the north-west side of the sediment spit marked A
and is obviously very shallow as grass is still visible in the channel around the spit.Water has
also pushed up the Spur channel past Kabuta.
G30 - May 1972 aerial photograph with labels
G31 - November 1972 aerial photograph with labels