214 DEVELOPMENT OF THE COASTAL BELT OF SOUTH AFRICA. 



there are no doubt some areas with a less run-ofif than the Perie, 

 there are undoubtedly others with a greater run-off. It may be 

 further suggested that, as our precise knowledge of the coastal 

 rain-Jbelt is so limited, it is risky to make general deductions; 

 this is, of .course, to some extent true; but after all we must make 

 our deductions from the knowledge we have, and not from our 

 absence of knowledge. 



The catchment area, which supplies Kingwilliamstown with 

 water, is part of the Perie Forest, and is one of the sources of 

 the Buffalo River. It is situated in the heart of this belt of in- 

 tensive rainfall, the elevation varying from about i,8oo feet 

 above sea level to 4,000 feet, the area being i^^t. square miles. 

 Accurate measurements have been kept for the past eight years 

 of the run-off from the catchment area, which will at least give 

 us some positive information to work on. 



Table 2. 



Run-off 

 in Million Gallons 

 from Catchment Area Percentage 

 Year. ' above Perie Dam. of Run-off. 



191 1 4.968 32 



1912 1,981 17 



1913 3.082 26 



1914 4.252 31 



1915 2,512 23 



1916 2,371 23 



1917 6,641 39 



1918 4.723 38 



Total 30.530. Yearly Average 3,816. 



Table 3. 



Percentage of Run-off. 



Average Precipi- Percen- 



Rainfall tation in Run-off in tage of 



Date. for period, mill, galls, mill, galls. Run-off. 



T911 Jan.-May .. 40.64 8,534 3.157 37 pc- 



June- Aug. 5.06 1,062 355 33 .. 



Sept.-Dec. 26.68 5,602 i,453 25 „ 



1912 Jan.-May .. 30.87 6,482 1,423 22 p.c. 

 June-Sept. 7 -So 1,638 155 9 ^ 



II .. 



Oct.-Dec. .. 17.34 3.641 402 



Tan.-March 26.60 5.5^6 2,127 38 



April-July 5.82 1,222 407 33 



Aug.-Dec. .. 23.37 4.907 548 II 



