The Rainfall
South-West Africa is really a continuation of the Bechuanaland plateau, a notoriously dry territory, and the rainfall is even less than in Bechuanaland, if we except the northern territories, since very little of the vapour from the distant Indian Ocean can reach the country. The Eastern slope, which faces the Indian Ocean, receives a fair supply of moisture. The Windhoek region has an average annual rainfall of 15 inches. Whirlwinds often herald the approach of the rain. In the warmer north and north-east 24 inches is often registered in a year. Great Namaqualand is much drier, 6 or 7 inches being about the average. The rain comes almost invariably in the form of violent thunderstorms which sweep along in a limited area. It is a common experience to travel over a stretch of dry and barren land to enter suddenly a tract of vivid green where the vegetation is in full activity, so local is the distribution of the rain. Severe hailstorms are sometimes responsible for much damage, since the hailstones are often as big as marbles. Within half an hour of the passing of one of these storms, the thermometer has been seen to drop from 110° F. to 68° F. Droughts of great severity continue for years together in these regions, but as soon as the rain comes, the country revives as if by magic; grass and flowers spring up from the steaming ground with amazing rapidity, and the once bare and blistered plain is transformed into a vast carpet of vivid green and brilliant hues.
The Namib has a rainfall of less than an inch, but in places where the desert borders the inner plateau, three or four inches may be registered during the year.
One of the journals of the Royal Meteorological Society has printed the rainfall record of South-West Africa. Dr. Emil Ottweiler is responsible for it, and the observations extended over periods varying from one to twenty-three years. This record is of real value, and we give the average fall at some of the stations mentioned.
| Stations. | Height above Sea Level. | Rainfall. |
|---|---|---|
| feet. | ||
| Luderitzbucht | 13 | 0·54 |
| Swakopmund | 23 | 1·16 |
| Windhoek | 5,350 | 14·07 |
| Grootfontein | 5,020 | 24·37 |
| Olukonda | 3,510 | 22·91 |
| Keetmanshoop | 3,373 | 5·85 |
| Bethanien | 3,068 | 4·52 |
| Berseba | 3,490 | 3·11 |
| Haris | 6,300 | 11·24 |
| Otjimbinque | 3,084 | 5·38 |
| Karibib | — | 6·01 |
| Zesfontein | — | 2·73 |
| Gibeon | 3,700 | 6·82 |
| Rehoboth | 4,700 | 10·45 |
| Oas | 4,500 | 18·69 |
| Gobabis | 4,650 | 18·53 |
| Omaruru | 3,800 | 10·85 |
| Hatsamas | — | 14·06 |
The rainfall, scanty as it is, generally descends in sharp storms and showers, and as the ground is often baked hard by the heats of the sun, it quickly runs away to the watercourses, but in recent years dams have been made in order to store the precious liquid, and a well-filled dam may hold sufficient water to supply a large farm for the space of a year or two.