274 J. S. Brown — Relation of Sea Water 



Akt. XXVII. — Relation of Sea Water to Ground Water 

 along Coasts; 1 by John S. Bkown. 



Contents. 

 Introduction. 



Sea water in shallow wells. 

 Sea water in deeper, drilled wells. 



Effect of special topographic and geologic conditions. 

 Law of equilibrium between fresh and salt water. 

 Nature of the contact between fresh and salt water. 

 Effects of pumping on salt content. 

 Seasonal variations in salt content. 

 Influence of tides on ground water. 



Introduction. 



Coastal ground-water problems: — The water from 

 wells and springs near seacoasts is often salty. On most 

 coasts saltiness due to sea-water is limited in shallow 

 wells to a narrow zone, usually a few hundred feet in 

 width, near the shore, but at some places it extends much 

 farther inland. Many wells near the shore encounter 

 fresh water near the surface and salt water at greater 

 depths. Pumping plants often yield salty water, espe- 

 cially after long-continued operation at a high rate. The 

 circumstances of contamination by sea water are modified 

 greatly by the kind of rocks and their structure and by 

 the topography adjacent to the shore, as well as by 

 climatic factors. 



Scope of field ivork. — In 1919 the writer made a study 

 of the groundwater resources of the New Haven area, 

 Connecticut. 2 This area includes a section of the coast 

 of Connecticut, lying east and west, of New Haven, which 

 will be referred to hereafter as the New Haven coast. 

 The length of this section is 30 miles in a straight line, 

 but owing to small irregularities, the actual coast line is 

 much longer than 30 miles. This work afforded a partic- 

 ularly favorable opportunity to observe some of the con- 

 ditions under which ground water is contaminated by sea 



1 Published by permission of the Director of the U. S. Geological Survey. 

 The illustrations were prepared by the Survey. 



2 Brown, John S. : Ground water in the New Haven area, Connecticut, U. S. 

 Geol. Survey Water-Supply Paper [awaiting publication]. 



This work was done in co-operation with the Connecticut State Geological 

 and Natural History Survey, under the direction of Herbert E. Gregory. 



