Information Series

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The DGS Information Series offers the public non-technical summaries of topics related to geology and/or ground water. Some Information Series numbers are available as web pages on the DGS web site, some in paper copy, and some in both media.


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Now showing 1 - 4 of 4
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    Ground Water in Delaware
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1998-02) Woodruff, K.D.
    Because of its "renewability" water is unique among earth resources that sustain and enhance life. No other mineral resource that we extract on a long-term and continuous basis can be counted on for at least some degree of replenishment within a human lifetime. This attribute allows a great deal of flexibility in management of the resource. In Delaware local rainfall, approximately 40" to 44" per year, renews part or all of our water supply on a regular basis. However, not all of the rain that falls is available for use. From this total rainfall must be subtracted the water that evaporates (about 20"/ year), the amount that is used by plants (about 3"/year), and the amount that runs overland to surface streams during storms (about 4"-5"/year). The remainder, approximately 13" to 15" is Delaware's bank of water for the year. This water is stored in a system of ground-water reservoirs, or aquifers, that underlie most of the State. Not only do these ground-water reservoirs provide water to wells but they also maintain the flow in surface streams during times of no rainfall. Streamflow between rainfall events is nothing more than the discharge of excess ground water.
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    Delaware's State Boundaries
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1989-06) Schenck, W.S.
    One hundred seventy-nine monuments help to mark Delaware's boundaries with Maryland, Pennsylvania, and New Jersey. Although there are only four major boundaries, there are seven boundary lines that make up the confines of the State. They are the east-west boundary, or Transpeninsular Line; the north-south boundary, or the Tangent Line, Arc, and North lines; the Delaware-Pennsylvania boundary, including the Top of the Wedge Line and the 12-mile Circle; and the Delaware-New Jersey boundary including the 1934 Mean Low Water Line and the Delaware Bay Line. Only the Transpeninsular, Tangent, Arc, North, 12-mile Circle, and 1934 Mean Low Water lines are monumented. The Delaware Bay Line is defined by the navigational channel. The boundaries described here evolved through long, complex histories (see references). They are based largely on adjudication in England of conflicting claims by the Penns and the Calverts for the Pennsylvania and Maryland colonies.
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    Domestic Water Well Construction
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1998-02) Talley, J.H.
    The storage and movement of ground water depends on the types of rocks and associated interconnected spaces in which the water occurs. The Piedmont Province in northernmost Delaware is underlain by crystalline rocks. Because of the massiveness and hardness of such rocks, they yield little or no interstitial water to wells. Water is stored in and moves through fractures, cracks, and solution cavities. The amount of water available depends on the number and size of openings, and the degree to which they are interconnected. Wells drilled in the Piedmont range from 100 to 400 feet in depth and yields are highly variable over very short distances.
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    Domestic Water Systems
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1998-02) Talley, J.H.
    Thousands of homeowners in Delaware currently rely on individual wells and water systems to provide water. In addition, hundreds of new wells and systems are constructed each year to provide water for those not served by public water systems.