the water line and sacrificial cathodic protection 
can usually solve the problem but become prohib- 
itively expensive. 
Different activities will dictate levels of expend- 
iture that can be justified economically. Control of 
biological encroachment and encrustation is both a 
structural and an operational probiem. It requires 
many solutions for different areas and species. 
Mechanical protection against environmental 
forces and erosion is less difficult. Both chemical 
and biological corrosion are technology barriers 
requiring improvements in corrosion-resistant ma- 
terials, protective coatings and devices. 
b. Future Needs 
The following observational and measurement 
capabilities are required to permit meaningful 
study and definition of coastal zone processes: 
—Methods and instrumentation for rapid on-site 
measurement of the engineering properties of 
sediments (i.e., static compression and shear 
strength, stability, bearing characteristics, and 
dynamic response). 
—Methods, equipment, and instrumentation for 
rapid core sampling of sediments and rapid (prefer- 
ably automatic) analysis of cores for primary 
physical, geological, and chemical properties. 
—Methods and instrumentation for continuous 
mapping of bottom sediments by primary geo- 
logical classification and primary physical proper- 
ties (e.g., density, sonic attenuation, and shear 
velocity). 
—Effective experimental methods and associated 
instrumentation and data processing systems for 
study of primary coastal processes, particularly 
those controlling sediment transport and deposi- 
tion. 
Special research and development programs are 
required for: 
—Development of improved modeling techniques 
for the study of coastal processes, including design 
of such improved model basin equipment as wind, 
wave, and current generators and controls plus a 
variety of materials for simulation of water and 
sediment properties. 
—Evaluation of new methods and equipment for 
major shoreline modification and construction and 
for island building. 
—Development of faster and less costly methods 
and materials to stabilize sediment. 
—Reduction of future costs by stockpiling sand, 
once a dredge is set up and in operation for 
another purpose. For example, after a dredge has 
replaced sand on a denuded beach, large stockpiles 
of sand can be strategically placed so that wave 
action automatically replenishes losses over future 
years. 
3. Conclusions 
Shore erosion is caused by wave action, tide 
currents, rain, wind action, and severe storms and 
is affected by offshore depths, slopes, shape of the 
shoreline, and other factors. In most cases, shore 
erosion can be controlled by properly planned and 
executed corrective measures. Shorelines have 
been misused and inadequately managed; major 
advances in knowledge must precede preventive 
and restorative action. 
Protection, modification, and extension of 
shorelines assume greatly increased importance in 
national planning. Optimum modifications of the 
shoreline and construction of fixed structures 
require a knowledge of oceanography, physiog- 
raphy, sediment properties, and natural processes. 
Planning and design prior to modification and 
construction require accurate definition of near- 
shore properties and processes and interrelated 
effects. 
Principal inadequacies of basic engineering cri- 
teria exist in environmental design, coastal plan- 
ning, conservation of sand, construction and modi- 
fication technology, movement and stabilization 
of sediment, and environmental protection. 
Coastal planning requires technical knowledge 
of shore processes, storm frequencies, and storm 
tide elevations for the area concerned. Undevel- 
oped or sparsely developed areas offer great 
opportunities for proper advance planning and 
development control. 
Sand is a rapidly diminishing natural resource 
requiring conservation. Protection of our seacoasts 
is not an insurmountable problem. Construction 
and modification in the coastal zone is frequently 
accomplished by antiquated surface methods and 
VI-109 
