In passing, it is of interest to note that this figure correlates 

 closely with figures obtained for sand removals from certain other har- 

 bours under similar conditions in India and in South America. 



STARVATION OP THE BEACHES 



The interception of the continuous sand supply from the south by 

 the removal of the sand from the harbour entrance has starved the ocean 

 beaches to the north thereof of their natural source of replenishment, 

 and erosion has consequently taken place. Further - and this is a very 

 serious aspect not generally appreciated - the deepening of the harbour 

 entrance to a depth in the vicinity of forty-five feet has contributed 

 much to the disturbance of the natural "profile of equilibrium" of the 

 whole sand formation. The effect of this will be appreciated when it is 

 realized that, whereas before there existed a feeble slope with a depth 

 approximating eight feet in low water, there is now a very deep and ex- 

 tensive hole exceeding forty-five feet in depth within a distance of the 

 shore that makes the maintenance of the stable sandy slope a matter of 

 great difficulty - if not one of impossibility. This has resulted in a 

 certain amount of deep water erosion, which is borne out by the results 

 of soundings taken over a long period. The early operations of the 

 smaller dredgers could not deal with the total flow passing the harbour 

 entrance, and undoubtedly some of the supply was allowed to pass and 

 continue towards the beaches, but since 1905 - when the larger tonnage 

 vessels were put into commission - an amount which appears to approximate 

 the estimated littoral drift has been removed annually by these vessels 

 and no sand at all has been allowed to pass the harbour entrance. The 

 ocean beaches have therefore been completely starved since that date. 



THE VARIATION OF HIGH WATER 



The effect of this "sand starvation" is graphically evidenced in the 

 movement of the high water mark over the years under review. Prior to 

 the construction of the entrance breakwaters in 1882, the high water mark 

 had remained reasonably stationary, as far as records are available, but 

 with the construction of the breakwater, an accretion of sand took place 

 north thereof which took the high water mark seawards along a stretch for 

 two miles noth of the breakwater, and an area of some 148 acres was added 

 to the beaches. This is evident from an examination of the plans of 1903, 

 and it is revealing to compare this plan with the survey of 1935 - the 

 period of maximum erosion when there was no attempt at replenishment of 

 wastage by any means. By the latter year, an area of 34| acres had been 

 lost on the South Beach alone, and over the whole stretch the accretion 

 of earlier years had disappeared. 



The movement of the high water line is well illustrated by an 

 examination of Table 1, which indicates the position of H.W.O.S.T. along 

 the line of prolongation of Rutherford Street. 



14 



