10 CHAPTER II 



the soil, consequently the water is admitted very tardily and 

 the run-off becomes very heavy. The amount, of run-off 

 depends largely, of course, on the topography of the ground, 

 whether mountainous or otherwise, the nature of the soil and 

 the date of the occurrence of the last rains. If the region is 

 mountainous and rocky, the run-off might very well be as high 

 as 80 per cent., and on heavy clay soils it will naturally be 

 much higher than on porous, sandy soil. It is not an exaggera- 

 tion to say that under most South African conditions, when 

 measured agronomically, the run-off varies from about 20 per 

 cent, to 80 per cent, of the rainfall occurring in heavy showers, 

 and is seldom as low as 5 per cent. 



The causes are now sufficiently clear of the low crop pro- 

 ductivity in South Africa as compared with parts of England 

 or countries similarly favoured, notwithstanding a superior total 

 rainfall. 



Seasonal and Annual Distribution Throughout South 

 x\frica. — The average annual rainfall in South Africa varies 

 from about 50 inches on the Natal coast to less than 2 inches at 

 Luderitzbucht, on the coast of the South- West Protectorate. 

 With the exception of the south coast and the south-west 

 corner of the Cape Province, the rainfall decreases from east 

 to west, and naturally the agriculture changes in correlation. 



At Wemmer's Hoek and Berg Eivcr Hoek, in the south- 

 western Cape, the rainfall is as high as 200 inches per annum, 

 and in some limited localities in the north-eastern Transvaal 

 and near Maritzburg, in Natal, it is nearly 70 inches per 

 annum. Over one-half of the territory comprised in the Union 

 receives a rainfall varying from 20 inches to less than 5 inches 

 per annum. Less than a quarter receives more than 24 inches, 

 sufficient, in effect, for grain crops to be reasonably productive 

 and profitable without the aid of irrigation. Nearly the whole 

 of this latter territory lies in the eastern portion of South 

 Africa, in which about 80 per cent, of the precipitation falls 

 during the summer months. 



The whole of Natal, Basutoland, approximately one-third 

 of the Transvaal and Orange Free State, and less than one- 

 tenth of the Cape Province, Griqualand East, Pondoland and a 

 few isolated areas receive about 25 inches of rainfall during the 

 year. 



The Union, generally speaking, may be divided into three 

 distinct areas as far as the seasonal distribution is concerned, 

 viz. : (1) The winter rainfall area, which includes the Western 



