2 Experiment Arrangement 



As part of the Coastal Inlets Research Program, a physical model facility was 

 created to address research and field problems of tidal inlets. This tool and 

 appurtenances necessary to study inlet problems are discussed in this chapter. 



Idealized Inlet Facility 



An idealized inlet was designed to fit in a 46-m- (150-ft)- wide by 99-m- 

 (325-ft)- long concrete basin with 0.6-m- (2-ft)- high walls.* The approach was to 

 design an inlet with simplified bathymetry and fairly steep beach slopes so that 

 additional features (such as an ebb shoal) could easily be added. Also, it was 

 anticipated that a fine sand would be used as both a tracer and as a fully mobile 

 bed, which could be placed over the concrete bottom in a thick veneer. A 1:50 

 imdistorted scale was assumed to determine reasonable inlet dimensions to model. 

 However, other scales can easily be assumed to accommodate the study of 

 specific processes due to the simplified bathymetry. 



Figure 1 shows the basin area. The ocean-side parallel contours were deter- 

 mined by using an equilibriiun profile equation fi-om Dean (1977) 



/j^ylx"^' (1) 



where h is the Stillwater depth, x is distance offshore, and A is determined by the 

 sediment grain size.^ A value of 0.24 was used, as it represented a relatively 

 steep beach. The contoured ocean beach slope extends to the 18.3-cm (0.6-ft) 

 mean low water (mlw) depth (or the 9. 1-m (30-ft) depth when scaled by 1:50) and 

 is then linearly transitioned to the basin floor at a depth of 30.4 cm (1.0 ft) (or 

 15.2 m (50 ft)) when scaled by 1:50). The inlet throat region converges to a 

 depth of 15.2 cm (or scaled to 1:50, 7.6 m (25 ft)) relative to a mlw datum. The 

 minimum width is 244 cm across the inlet between mlw contours (or when scaled 

 by 1:50, it represents a width of 122 m (400 ft)). Figure 2 shows the inlet throat 

 and entrance channel with parallel jetties which have a spacing of 3.66 m 



'A table of factors for converting non-SI units of measurement to SI units can be found on page vii. 

 ^ For convenience, symbols and abbreviations are listed in the notation (Appendix C). 



Chapter 2 Experiment Arrangement 



