(b) effect of (lake] level changes on erosion; and 



(c) effect of breakwaters, groins, and other structures. 



Even though mathematical modeling of shoreline evolution has in- 

 spired some research, it has received only limited attention from 

 practicing engineers. The present methodology is based mainly on 



(a) the local experience of engineers who have a deep knowledge 

 of their sectors, understand littoral process, and have an inherent 

 intuition of what should happen; and 



(b) movable-bed scale models that require extensive field data 

 for their calibration. 



In the past, theorists have been dealing with idealized situations, 

 rarely encountered in engineering practice. It seems that mathematical 

 modelers have long been discouraged by the inherent complexity of the 

 phenomena encountered in coastal morphology. The lack of well-accepted 

 laws of sediment transport, offshore-onshore movement, and poor wave 

 climate statistics have made the task of calibrating mathematical 

 models very difficult. 



Considering, on one hand, the importance of the subject of deter- 

 mining the effect of construction of long groins and navigation 

 structures and on the other, the progress which has been made in 

 determining wave climate and littoral drift, it now appears that a 

 mathematical approach could be useful. 



The complexity of beach phenomena could, to a large extent, be 

 taken into account by means of numerical mathematical scheme, (instead 

 of in closed-form solutions) , dividing space and time intervals into 

 small elements, in which the inherent complexity of the morphology 

 could be taken into account. 



Furthermore, better knowledge of the wave climate, a necessary in- 

 put, will allow a better calibration of coastal constants such as 

 found in the littoral drift formula. 



This study emphasizes the relative importance of various reports and 

 reviews the most important ones. Conclusions based on this review are 

 presented, pointing out the deficiencies of the state-of-the-art. (Sub- 

 sequent investigators should attempt to bridge the remaining gaps.) 



The reports are presented individually, primarily in chronological 

 order. Two milestone developments from this survey are reports by 

 Pelnard-Considere (1956) and by Bakker (1968b) . Others are extensions 

 and refinements, experimental verifications, support papers, numerical 

 procedures, and side issues, including the latest developments on 

 "hooked beaches" or crenulate-shaped bays. 



