368 Report S.A.A. Advancement of vScience. 



at a total cost of ^5,000,000 to irrigate an additional 100,000 acres 

 in the Transvaal. Unfortunately, it is on far too ambitious a scale 

 for the present requirements of the two Colonies, and it cannot be 

 commenced on a smaller one and be subsequently enlarged. The 

 time may come, however, when it will be wanted, and it is as well 

 that it should not be lost sight of. 



Schemes of the magnitude described above may have the advan- 

 tage of rendering the climate in the neighbourhood more humid, 

 and, if this proves to be the case, their benefit will extend beyond 

 their own immediate limits. 



13. Inter-Colonial Co-operation. 



Irrigation schemes of all sizes have now been discussed broadly. 

 and chiefly from the engineering point of view. It has been pointed 

 out that each class of scheme has its own special utility, and that. 

 if any scheme fulfils the main requirements of feasibility, suitability, 

 desirability, and moderate financial success, it can be undertaken with 

 confidence. It is, perhaps, needless to add that each project should 

 be carefully and fully investigated before it is started, so as to avoid 

 the commission of costly mistakes. It now remains to make a few 

 general observations on the main subject of this paper. 



Although the Colonies are at present only in their preliminary 

 stage of development, difficulties have arisen in regard to water 

 questions connected with the Vaal, owing to the deficiency of its 

 supply at the end of the fair season. During each of the last 

 three years its flow at Christiana has practically ceased for two or 

 three months, and is likely to fail this year for a considerably longer 

 period. The restriction of irrigation from its upper tributaries has 

 even been suggested, so as then to secure supply to the lower riparian 

 towns in Cape Colony, including Kimberley. It is hardly necessary 

 to point out that, even if this were practicable, it would be a 

 retrograde step to take, and it would introduce inter-colonial friction 

 instead of co-operation. It is, however, not practicable, as the laws 

 of each Colony run only within its boundaries, and the upper Colony 

 would certainly never consent to being deprived of its natural 

 resources for the benefit of the lower Colony. Considering the case 

 of two Colonies separated by a river, the best way, theoretically, is 

 to divide its flow between them in proportion to their contributions 

 to its discharge. Such discharge depends upon the extent of the 

 catchment area, the nature of the country, and the intensity and 

 amount of the rainfall. To determine the discharge to which each 

 Colony has a fair claim would take many years of observation, and, 

 even when determined from the results ascertained, the proportion 

 arrived at might, with the variation of rainfall in a subsequent 

 season, then prove an unfair one. Owing to the great fluctuation in 

 the flow of even these large rivers, to depend upon them in their 

 natural condition will frequently lead to difl^iculty. The obvious 

 remedy is to reduce these fluctuations artificially by means of storage 

 weirs and dams, whereby a definite amount of supply can be 



