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8. SALTWATER INTRUSION 



8 . 1 INTRODUCTION 



Many coastal cities rely on local groundwater to meet domestic and 

 industrial needs. With the increasing demand due to greater population and 

 industrial concentrations along the coastline coupled with sea level rise, 

 the potential for saltwater contamination of the aquifer will increase. As 

 in other cases , there are two general approaches to responding to this 

 problem: 1) abandonment of use of the resource, or 2) adoption of 

 management and prevention measures to reduce salinity intrusion. 

 Considerable experience has been gained in coping with saltwater intrusion 

 not principally due to sea level rise, but due to excessive use of the 

 groundwater resource. Yet sea level rise and excessive groundwater usage 

 both decrease the seaward directed piezometric gradient and are, in some 

 respects, comparable. This chapter reviews the various types of saltwater 

 problems that can occur due to sea level rise and the capability to predict 

 and respond to such intrusion. 



8.2 LITERATURE REVIEW 



The subject of saltwater intrusion into coastal aquifers has been of 

 interest for several centuries. Recently the interest has increased due to 

 intense use of coastal groundwater resources . Methods have been developed 

 to predict the effects of differing usage and management procedures . 



Todd (1980) has presented a review of the theory and management 

 practices related to saltwater intrusion in coastal aquifers. In addition 

 to the excessive pumping and sea level rise, saltwater intrusion can result 

 from surface drainage canals which both lower the freshwater head, and if 

 salt water flows into the canals, surface contamination. In recognition of 

 this problem, the State of Florida has enacted legislation to establish a 

 saltwater barrier line in areas prone to saltwater intrusion through canals 

 (Hughes, 1979). There are a number of approaches for controlling saltwater 

 intrusion, as summarized in Table 8.1. Several of these techniques will be 

 illustrated later by examples. 



