botswana/namibia - Cour international de Justice

G8 - Definition of floodplain and bankfull flow
266. Continuing its misinterpretation of the facts, the Namibian Memorial states
"Kasikili Island lies within the flood plain of the Zambezi River which covers roughly the
entire triangle bounded by lines connecting Katima Mulilo on the north, Ngoma Bridge on the
south and the Mambova Rapids on the east (See Fig.4, following page 17 infra.). This whole
flood plain, including Kasikili Island itself as well as the two channels of the Chobe river is
under water five months of the year on the average." (emphasis supplied). (Namibian
Memorial, p.7, para.21).
267. This totally misrepresents the true position. In scientific terms a flood plain is distinct
from the river channel itself, being " the surface adjacent to the channel, separated from the
channel by banks, and built of materials deposited in the present regime of the
river".(Professor Sefe's Second Opinion, p.6, para.12, citing Baker et al, 1988, at page 95
showing the definition of floodplain and bankfull flow). The course of the Kwando-Linyanti-
Chobe River is largely determined by the numerous faults in the area (Professor Sefe's Second
Opinion, Appendix 4, Thomas and Shaw 1991).
268. The pronounced channels of the Chobe River can only have been cut by water flowing in
a downstream direction. Floods do not obliterate channels; they are simply submerged, but
continue their draining function as the deepest parts of the flooded zone. The continued
presence and greater depth of the northern channel is to be observed on the satellite imageries,
in particular, the classified figures 15, 21 and 25, in Professor Sefe's Second Opinion. Figure
15 is reproduced at page 99, and Figures 21 and 25 are reproduced at pages 197 and 199
(Chapter 6, para 455, below).
(iii) The misconception that there is no downstream flow through the northern channel
throughout the year
269. The Namibian Memorial develops Professor Alexander's thesis in the following passage:
"It is of cardinal importance in understanding the issues in this case for the Court to keep in
mind that all of the maps and photographs depicting this Island (except for some of the
satellite images in the Alexander Report) were made during the dry season when there is no
water flowing through the river. The visual images that appear in these representations as the
seemingly clearly defined northern and southern channels around the island are no more than
stagnant pools of water caught behind the Mambova Rapids after the annual flood
subsides".(Namibian Memorial, p.22,para.66).
270. This passage produces a direct conflict with the map evidence produced by Namibia's
cartographic expert, Mr. R.W.Rushworth (See Chapter 8 of this Counter-Memorial).
I. IT IS NOT CORRECT IN SO FAR AS IT RELATES TO THE NORTHERN CHANNEL
271. Article III of the 1890 Agreement speaks of a line which "runs eastward..till it reaches
the River Chobe : and descends the centre of the main channel of that river to its junction of
the Zambezi, where it terminates." The term "descends" in Article III stresses the significance
of gradient in the treaty-makers' adoption of a river as a geographical feature by which to
locate the boundary line. Similarly, gradient is envisaged in the use of "ascends" in relation to