211 



Robert Biggs 



Roy F. Weston, Inc. 



Building 5-2 



Weston Way 



West Chester, PA 19380 



SECT. 3. COMPACTION EFFECTS 



With reference to the statement (in Sect. 3.1) "... However, no 

 investigations have been found which identify any specific effects of the 

 inverse problem, i.e., the effects of sea level rise on compaction and 

 subsidence ...," I offer the following addition: Hydroisostasy , the 

 concept that meltwater from Pleistocene ice caps produces loading of the 

 ocean floor that causes significant global deformation, has been examined 

 qualitatively by Daly (1925) and quantitatively by Walcott (1972) and 

 Chappell (1974) . The model of hydroisostatic adjustment of continental 

 shelves rests on the assxamption that the earth adjusts isostatically to 

 changing surface loads applied over relatively large regions . The 

 deformation through time, in response to changing surface loads, has been 

 refined by Chappell et al . (1982) and has been applied to an area of the 

 Australian coast of North Queensland. 



Figure 1 in Chappell et al . (1982) illustrates the effect of a 150-m 

 sea level rise on the deformation of a continental shelf and the adjacent 

 shoreline. As the shallow shelf (roughly 200 km wide) is loaded with 50 m 

 of water, it sinks under the weight of water while adjacent land areas rise 

 (designated by F in Fig. la). The effect of the water loading, illustrated 

 in Fig. lb, is to depress the area seaward of the present coast to a 

 maximum depth of 4 m greater than the eustatic rise. 



SECT. 9. UPRIVER SALTWATER PENETRATION 



You might want to add an example in Sec. 9.4 from Delaware Bay: Hull 

 and Tortoriello (1979) and Hull (1986) have estimated the salinity 

 intrusion into Delaware Bay resulting from a 13-cm predicted sea level rise 

 for the period 1965-2000. Expressed as the maximum 60 -day chloride increase 

 along the Delaware estuary, values as high as 200 mg/L might be expected 

 (Fig. 8 in Hull and Tortoriello, 1979). 



