THE NEARSHORE MOVEMENT OP SAND AT DURBAN 

 by 

 A. Kinmont 



A description of the beach erosion problem at Durban, Natal, 

 South Africa, first appeared in vol. 10 - No. 1 of the Bulletin 

 in July 1956. The following article includes a discussion of 

 the effectiveness of various remedial measures adopted to combat 

 the shore erosion, and first appeared in the published papers 

 (C.S.I.R. Sympos. No. 52, Pretoria, S. A., Mar. 1961) of a 

 Symposium on Marine studies off the Natal Coast arranged by the 

 Natal Regional Research Committee of the South African Council 

 for Scientific and Industrial Research. The paper is reproduced 

 here with the kind permission of the author who is City Engineer 

 at Durban. 



INTRODUCTION 



The movement of sand off-shore is a problem of vital importance to 

 the City of Durban - from the two aspects of harbour development and beach 

 preservation. Unfortunately these two aspects are antagonistic in that 

 there is no doubt whatsoever that the problem of beach erosion followed 

 upon the development of the Durban Harbour. 



The harbour itself is sited within one of the finest natural bays on 

 the continent; however the bay was of a later geological formation than 

 the mainland, for it was formed from the building up, by wind and current 

 action, of the Durban Bluff and the Point, two features which interrupt 

 the general straightness of the Natal coast. The Point spit, representing 

 the youngest formation, is of loose material which possibly began as an 

 off-shore bar, and is held in equilibrium by the different forces and 

 conditions of nature. If this balance is disturbed, then this spit may 

 well tend to disappear and could turn Durban Bay again into an open road- 

 stead. Thus the importance of the stability of the foreshore to the City 

 will be appreciated. 



EARLY HISTORY OF HARBOUR 



An examination of early Admiralty charts and other documentary evi- 

 dence shows beyond doubt that the channel depth at the entrance to Durban 

 Bay remained stationary at six feet L.W.C.S.T. from 1685 to 1880, a period 

 of nearly 200 years, while it can safely be assumed that this condition 

 of equilibrium existed for centuries earlier, after the formation of the 

 protecting arms of the Bluff and later the Point. 



In 1882, the Innes Breakwater was commenced and with its progress 

 seaward the bar at the Harbour entrance was gradually shifted outwards 



