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(assume increase) and F (decrease). Typically, the overall effect will be 

 an increase in K, which means easier flow admittance or better repletion. 

 The O'Brien relationship between the spring tidal prism, P, and A^ is 



Ac = aP"* (10.2) 



where a and m are empirical coefficients which vary somewhat with the 

 prevailing wave climate and other local conditions. The significance of 

 this relationship is that it implies inlet widening and/or deepening with 

 prism. Sea level rise in most cases will increase the prism (greater 

 repletion), to which the inlet flow area will respond likewise. Equation 

 10.2 is particularly applicable to sandy inlets, as described in section 6. 

 Increasing prism means greater sand flushing ability of the channel. The 

 sand is transported by higher currents out of the channel, both bayward and 

 seaward, to flood and ebb shoals, respectively. With increasing prism, 

 there is likely to be a corresponding increase in the volume of these 

 shoals. Furthermore, as the sea level rises the deltas must grow in 

 elevation to keep up with the rise, implying that any natural bypassing of 

 sand would reduce and that downdrift erosion would increase. 



Stabilized inlets will be affected strongly by a large sea level rise. 

 The protective jetties, which retard the ability of the littoral drift to 

 enter the navigational channel and reduce the wave climate in the channel, 

 would become less effective as they are submerged. Also, the stability of 

 the jetties may be reduced due to increased wave heights as a result of sea 

 level rise (National Research Council, 1987b). 



The sea level rise scenario imposes a much more gradual change in the 

 inlet/bay system than, for example, channel dredging. There should be 

 enough time for the system to keep pace with water level rise, with the 

 attainment of quasi-equilibrium under the prevailing hydrodynamic forces 

 and sediment movement. Equilibrium is determined jointly by hydraulic 

 conditions characterized by the repletion coefficient (Eq. 10.1) and by 

 sedimentary requirement as per Eq. 10.2 (O'Brien and Dean, 1972). 



It is also self-evident that shoreline response as far as inlets are 

 concerned is contingent upon the availability or lack of sediment supply. 

 For example, the barrier islands of the Mississippi-Alabama coast have been 



