FROM THE LAKE NGAMI BASIN, BECHUANALAND. 401 



" Now, as I have said, the lowest point of the whole Kalahari basin north of the 

 Orange river is the Great Makarikari Salt Pan, and unless there was some rising 

 ground between it and the Molopo and Nosop rivers, those rivers would probably 

 have drained into it instead of into the Orange river as they do *. 



"At the present day the importance and capacity of Lake Ngami is infinitesimal when 

 compared with the huge extent of the Okovango marshes and periodically flooded area 

 to the north and north-east, and it is important to realize that the origin and only 

 source of all the streams and mai'shes in Ngamiland is the great Okovango river (the 

 rainfall in Ngamiland being of comparatively little importance in this respect), which 

 rises in the Mosamba Mountains in Portuguese West Africa, and drains an enormous 

 area with a very heavy rainfall from September to February. The result of this is 

 a huge periodical flood which flows down the Okovango into the marshes of Ngami- 

 land, of which Lake Ngami is really a part. These gradually rise and overspread 

 hundreds of square miles of the surrounding country, which is extraordinarily flat, the 

 inundation reaching its highest point not during the rainy season, but towards the end 

 of the dry season, about August or September. None of this water finds its way out 

 to the sea, but after filling the marshes north of the lake, and formerly the lake itself, 

 flows on down the Botletle until lost by evaporation and percolation. No doubt 

 on many occasions in the past some of this flood has reached the Great Makarikari 

 Salt Pan, which is the lowest point of the whole Okovango river-system ; but 

 apparently no flood has been large enough to reach the Makarikari for many years, 

 although an old dry river-bed can be traced a long way to the east of the present end 

 of the Botletle. 



" There is no doubt that it is only quite recently that the water-supply of Lake 

 Ngami has failed, and the lake partially dried up, for although the processes which 

 brought about this result must have been iu progress long before Livingstone's visit 

 in 1849, his description of the lake and his picture clearly show it' to have been then 

 an imposing sheet of water, and to a great extent open. To-day Lake Ngami is just 

 a great reed-bed, which dries up almost entirely by the beginning of the periodical 

 flood. Whether there are any large pools and open sheets of water in the interior of 

 this reed-bed which do not dry up I cannot, unfortunately, say, as no white man has 

 ever been far into the lakef, and native evidence is not unanimous on the subject; 

 but I am certainly inclined to agree with those who say that by about March the Lake 

 is absolutely dry on the surface, except for a few shallow pools at the south-east corner, 



* " The watershed between the Zambesi and the Okovango river-systems is a low and very ill-defined one, 

 and it is a doubtful question whether during the times of highest flood the Okovaugo marshes are not 

 connected with the Chobe marshes." 



t " It was very unfortunate that this point could not be cleared up, but owing to the sudden serious illness 

 of my companion, a hasty retreat had to be made to the railway-line before the exploration of the centre of 

 the Lake had been carried out." 



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