COASTAL SCOUR PROBLEMS AND METHODS 

 FOR PREDICTION OF MAXIMUM SCOUR 



PART I: INTRODUCTION 



General 



1. Scour at coastal structures is a serious problem that causes damage 

 to structures. Coastal engineers have long recognized the consequences of 

 scour at and in the vicinity of the toe of structures, and elaborate and 

 expensive toe protection schemes have often been implemented. In instances 

 where appreciable scour has already occurred, a common solution has been to 

 fill the scour hole with stone or other suitable material. Under certain wave 

 and/or current conditions, the base which supports coastal structures is 

 eroded and partial or total failure can occur. Because it is usually very 

 costly to repair these structures, proper initial design and construction 

 methods that consider scour potential are desirable. This report is concerned 

 with examining existing scour prediction methods for typical coastal 

 structures/facilities . 



Purpose 



2. The purpose of this report is to review existing methods for scour 

 prediction and to determine which of these methods are most appropriate for 

 the various applications that are of interest to field engineers. 



Background 



3. Scour in the vicinity of coastal structures has been the subject of 

 research efforts for many years. To adequately study this problem, 

 researchers must address the various effects of waves, wind, tide, currents, 

 and storm surge on both the structure itself and the bed on which the 

 structure resides. Among the most common are problems related to toe scour at 

 rubble-mound structures, scour at the base of piles, toe scour at vertical 

 seawalls, and scour at horizontal pipelines. Prediction methods for these 

 types of scour problems vary from using rules of thumb, to empirically derived 

 equations to theoretically derived relationships. When existing computational 

 methods are insufficient, physical model studies often are performed. For 



