Chapter 16 



SEDIMENTATION IN HARBORS 



Joseph M. Caldwell 



Chief, Laboratory Section 



Engineering and Research Branch, Beach Erosion Board 



Corps of Engineers, Department of the Army 



Washington, D. C. 



This chapter will be devoted to a brief discussion of the engineering 

 and, to some extent, the economic aspects of sedimentation in harbors. 

 Many of the statements herein will be recognized as applicable to 

 navigation channels in general as well as to harbor channels and an- 

 chorages. 



In most harbors, man has artificially increased the depth of water 

 over that normally existing at the locality in order to accommodate 

 the movement, anchoring, and berthing of vessels. The tendency for 

 natural forces to restore the normally existing depths is the crux of 

 the sedimentation problem. 



For the purposes of this discussion, sediment is considered to be any 

 detritus, from gravel to clay particles, which moves into and is de- 

 posited in commercial harbors by natural means, such as stream flow, 

 tidal flow, or wave action. Harbors are found along the open coast, 

 in the tidal rivers and bays connected with the ocean, along the fresh- 

 water rivers, and along the larger interior lakes. The causes and mag- 

 nitude of shoaling in these different types of harbors are varied. Cor- 

 respondingly, the attempted cures, both successful and unsuccessful, 

 have varied. Generally speaking, all have been expensive. Harbors 

 have been classified as river-channel harbors, off-river harbors, fall- 

 line harbors, tidal-channel harbors, off-channel tidal harbors, and 

 shore-line harbors; the terms will be explained in turn below. 



RIVER-CHANNEL HARBORS 



Many fresh-water non-tidal riverside harbors are developed in the 

 river channel proper. Examples of such harbor developments are: 

 Baton Rouge, Louisiana; St. Louis, Missouri; Pittsburgh, Pennsyl- 



291 



