CHAPTER 5 



PLANNING ANALYSIS 



Sol GENERAL 



Coastal engineering problems may be classified into four general 

 categories: shoreline stabilization, backshore protection (from waves and 

 surge), inlet stabilization, and harbor protection. (See Figure 5-1.) 

 A coastal problem may fall into more than one category. Once classified, 

 there are various solutions available to the coastal engineer. Some of 

 these are structural; however, other techniques may be employed, such as 

 zoning and land use management. This Manual deals primarily with struc- 

 tural solutions, but basic design factors may also apply to other types 

 of solutions. 



Figure 5-1 indicates, structures or protective works that fit into the 

 four general problem classifications and factors that must be considered 

 in analyzing the problem. Hydraulic considerations include wind, waves, 

 currents, tides, storm surge or wind setup and the basic bathymetry of the 

 area. Sedimentation considerations include the littoral material and 

 processes (ioe„, direction of movement; rate of transport, net and gross; 

 and sediment classification and characteristics) and changes in shore 

 alignment. Navigation considerations include the design craft or vessel 

 data, traffic lanes, channel depth, width, length and alignment. Control 

 structure considerations include selection of the protective works eval- 

 uating type, use, effectiveness, economics, and environmental impact„ In 

 selecting the shape, size, and location of shore-protection works, the 

 objective should be not only to design an engineering work which will 

 accomplish the desired results most economically, but also to consider 

 effects on adjacent areas. Economic evaluation includes the maintenance 

 costs and interest on and amortization of first cost. If any plan con- 

 sidered would result in enlarging the problem by extending its effects to 

 a larger coastal stretch or prevent such enlargement, the economic effect 

 of each such consequence should be evaluated. A convenient yardstick for 

 comparing various plans on an economic basis is the total cost per year 

 per foot of shore protected. 



Effects on adjacent lands are considered to the extent of providing 

 the required protection with the least amount of disturbance to current 

 and future land use, environmental factors, and aesthetics of the area. 

 The form, texture, and color of material selected for the design should be 

 considered as well as how the material is used. Proper planning analysis 

 also requires consideration of legal and social consequences where shore 

 protection measures may be expected to result in significant effects on 

 physical or ecological aspects of the environment. 



Tlie following sections describe the most common structural solutions 

 now used to meet functional requirements, and provide guidelines for the 

 application of these solutions. This manual treats only the structural 

 solutions to problems. The environmental effects of all such solutions 

 must, by law as well as normal engineering concerns, be studied. 



5-i 



