waves. However, techniques to measure longshore transport described below and 

 further developed herein are equally applicable to riverine transport. A 

 review of riverine methods and apparatus for measuring sediment transport is 

 presented in Appendix A together with methods for measuring transport in the 

 nearshore. 



Methods of estimating transport 



4. Sediment transport rates have traditionally been determined using 

 one of four methods: measurement of topographic change occurring as a result 

 of the transport, such as erosion or deposition at a coastal structure; 

 measurement of fluorescent-dyed or radioactive sand tracer movement; use of an 

 analytic or empirical relationship with measured or calculated waves and/or 

 currents to infer a rate; and measurement of the transport through time using 

 some type of apparatus or instrument. Each of these methods has particular 

 advantages and disadvantages. 



5. The topographic change method (e.g., Caldwell 1956; Bruno, Dean, and 

 Gable 1981) results in an estimate of relatively long-term sediment transport 

 (on the order of weeks to months) and has the advantage of being capable of 

 encompassing high-energy events. However, the relationship between wave and 

 current conditions during the averaging period and the resulting transport 

 cannot be sharply defined, as the processes are smoothed through time. In 

 addition, it is difficult to distinguish between changes caused by cross-shore 

 and longshore components of transport. 



6. The use of a tracer consisting of dyed ambient sand (Komar and Inman 

 1970, Inman et al . 1980, Kraus et al . 1982) can provide an estimate of 

 transport on the order of hours to days in a relatively low- energy wave 

 environment; however, this method is extremely labor-intensive, and consistent 

 results are difficult to obtain (Kraus et al . 1982). 



7. Empirical relationships relating sand transport to measured forcing 

 quantities (wave characteristics, water velocity, etc.) can be used to 

 estimate transport over any time interval , depending on the type of input 

 data. However, the correlation between longshore transport rates measured in 

 the field and rates predicted using an empirical or analytical relationship is 

 relatively weak and may be questioned (Greer and Madsen 1978). 



