207 



Why emphasize resonance effects? What proportion of world coastlines 

 have strong tidal resonance? 



The discussion of Mann (1987) in Section 4.4 is misleading and 

 unrealistic. Suggest either complete rewrite or omission of this poor 

 example . 



We cannot neglect changes in sediment load and water discharge with 

 climate changes. Climate change may impact these two variables, which in 

 turn will impact tidal range impacts. 



Shoaling of estuaries/harbors makes quantification of these tidal 

 range effects difficult. Our knowledge is insufficient to predict large- 

 scale shoaling that can impact tidal range changes. 



We need improvement of basic understanding of sediment transport: 

 emphasize basic research and not rely on bulk, empirical sediment transport 

 formulae. The largest potential payback of all coastal engineering might 

 be improvement in understanding the physics of sediment transport. 



Tidal range depends not only on growth of parent tides (e.g., M2 , S2, 

 N2 , Kl , 01, SI, etc.) but also on harmonic growth (amplitude and phasing). 

 Our understanding of these nonlinear processes must improve if we are to 

 predict accurately tidal range impacts (de Ronde presented some interesting 

 examples) . 



SECT. 7. SHORELINE RESPONSE MODELING 



This is a key area for setting up responses to sea level rise. Our 

 present understanding is limited to qualitative and semiquantitative models 

 of shoreline response. 



The Bruun rule has been the bane of coastal engineers for decades. 

 Geologists have adopted this rule without adequate caution and applied it 

 indiscriminately at times. We need a new and improved understanding of 

 shoreface response to relative sea level rise. 



The basic understanding of formation of barrier beaches is 

 qualitative. We do not have a quantitative model for formation of barrier 

 beaches . 



The elementary physics of sediment transport, both near bed and 

 suspended load, is inadequate for quantitative models. In a sense, all 

 models now are empirical and qualitative. 



