TRESIDKNTIAL ADDRESS SECTION A. 33 



The solids in suspension at the Kimberley Waterworks for 

 ion samples taken at various times has varied from 7 to 2,872 

 l-arts per million, or an averat^e of (^/ per million, as shown in 

 I lie following table : 



Solids in Suspension in Parts per Million. * 



2872.0 



1640 



16.0 



7.0 



1 271.0 



277.0 



qSi.o 



557-0 



499.0 



163.0 



Average per 10 samples 687.3 



Discharge of the Vaal River. 



The quantity of water passing down the Vaal River during 

 the years 1900 to 1905 and 1910 to 1919 is shown in Table " D." 

 The discharges during the former period, 1900-1905, were 

 obtained by Mr. Laschinger, and during the latter period by 

 the Government Irrigation De])artment and the Rand Water 

 Board. Table " E " shows the average monthly discharge over 

 a period of 13 years, and it will be observed that January is the 

 month of greatest flow, and June that of lowest flow. 



Table " F " shows the discharge in cubic feet, the average 

 annual rainfall, and the percentage run-off. The run-off", as will 

 be obsen-ed, varies very greatly, the lowest being 1.55 per cent, 

 during the hydrographical year 1913-1914. and the highest ?,S-~S 

 per cent, during the year 1917-1918. 



The monthly discharge of the Vaal River at Vereeniging 

 for the years mentioned above is shown graphically on Plate 

 6. Plate 7 shows the discharge of the Vaal River 

 at Vereeniging and Kimberley for a. period of one year, and it 

 will be observed that the time lag with reference to floods usually 

 varies from about 7 to 11 days. 



* These figures have been supplied by F. S. Lynch, Esq.. General 

 Manager, Kimberley Waterworks. 



