By Ralph C. Heath
This report is available as a pdf below
Two of the primary responsibilities of the U.S. Geological Survey are to assess the Nations water supply and to develop the understanding necessary to predict the environmental consequences of alternative means of developing and managing water resources. To carry out these responsibilities the Geological Survey conducts studies, many in cooperation with State and local agencies, to determine the quantity and quality of the Nations water resources and the response of hydrologic systems to both natural and manmade stresses. The results of the studies are made available in numerous ways, including published reports, written and oral responses to specific requests, and presentations at scientific and public meetings.
Although most reports are designed to meet the technical needs of those engaged in the development, management, and protection of water supplies, the U.S. Geological Survey has long recognized the need to present the results of its studies in a form that is also understandable to those who are affected by and who benefit from water developments. To better meet this need, the Water Resources Division of the Geological Survey expanded the preparation of general-interest reports in 1980. The reports planned as a part of this program deal both with specific water-related problems, such as abrupt land subsidence that results in sinkholes and water logging of the land in urban areas due to a rising water table, and with general topics of broad public interest, such as this report which describes the ground-water resources of the Nation.
Ground water occurs in the rocks that form the Earths crust and thus is in the domain of geology. Because the geology of the country is complex, the occurrence of ground water, in detail, is extremely complex. This complexity makes it difficult for many people to develop an understanding of ground-water occurrence and availability and has resulted in problems of ground-water depletion and ground-water pollution whose correction will be both difficult and expensive. Fortunately, such problems are not yet widespread and can, with intelligent application of existing ground-water knowledge, be avoided in most other areas. However, to realize this goal, those engaged in water-resources development and management and the general public need to become better informed on the Nations ground-water resources. The purpose of this report is to help meet this need.
The report consists of sections that deal concisely with discrete parts of the overall subject. The sections are arranged in a sequence that begins with a discussion of the general aspects of geology and rocks and proceeds to a description of the ground-water systems in the 15 ground-water regions into which the United States, Puerto Rico, and the Virgin Islands are divided. An attempt has been made to illustrate most of the important concepts and topics covered in the discussions. It should be noted that the block diagrams used for illustration in the regional discussions are intended to show the major features of the ground-water system in the region rather than a specific part of a region.
The section entitled Ground Water Regions of the United States
also warrants special mention. It includes maps that show the boundaries of
the regions and tables that summarize the physical and hydrologic characteristics
of the regions. Thus, it serves as a bridge between the preceding sections which
deal with the general aspects of geology, ground water, and classification of
ground-water systems and the following sections which cover each of the 15 regions.
The tables will be useful to those who wish to compare the characteristics
of the different regions. Many readers may also find it useful to refer back
to these tables from time to time as they read the regional descriptions.
Finally, metric units are used throughout the report but, as an aid to readers who are not familiar with some of these units, the equivalent values in inch-pound units are given at the back of the report. Also, definitions of certain technical terms are included at the end of the table of contents for the benefit of readers who are not familiar with some of the geologic and ground-water terms used in the report.
Definitions of terms
Ground water-an invaluable resource
Geology and ground water
Basic ground-water concepts and terminology
Classification of ground-water regions
Ground-water regions of the United States
References to regional discussions
Units and Conversions
Relation of units of hydraulic conductivity, transmissivity,
recharge rates, and flow rates
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Last modified: Friday, January 11 2013, 03:42:29 PM