- 46 - 



Both case studies found that sea level rise will have 

 significant impacts. Research Planning Institute concluded 

 that a 1.5 meter (five foot) rise in sea level would innundate 

 one-quarter of Charleston if no additional bulkheads or seawalls 

 were constructed.^/ They also calculated that areas in 

 Charleston that are now flooded once every 100 years would be 

 flooded once every 10 years. Leatherman concluded that a 

 1.5 meter rise would claim much less land around Galveston, 

 provided that the existing network of levees and seawalls were 

 maintained.^/ However, he estimated that such a rise would 

 double the area flooded every 15 years. Because Galveston 

 is already vulnerable to storms, Gibbs concluded that the 

 resulting annual storm damage in this area would increase to 

 $105 million from $23 million. 10/ 



Quantitative projections of the effects of sea level rise 

 on salinity in surfacewater and groundwater have only been made 

 in limited cases. The Delaware River Basin Commission has 

 estimated the effects of historical sea level trends on salt 

 concentrations in the Delaware River. 11 / It plans to examine 

 the effects of the scenarios reported here, which may threaten 

 aquifers recharged by the river and possibly Philadelphia's 

 current water intakes during droughts However, no comprehensive 

 analyses have been undertaken of salinity intrusions from sea 

 level rise. 



