An indexing and classification system for earth-science data bases

Abstract

An indexing and classification system for water and other earthscience data is defined for use in the U.S. Geological Survey's National Water Information System (NWIS), and other similar systems such as the U.S. Environmental Protection Agency (EPA) Water Quality Control Information System (STORET). All five-digit EPA parameter identification codes, which are used in both of these systems, have been classified into a three-level hierarchical system of categories called groupings. The first level in the hierarchy is called the Sample Medium level and includes 42 groupings that classify a parameter code according to the environmental matrix or phase from which the sample is collected. The second level in the hierarchy is called the General Physical/Chemical level and consists of 12 groupings that classify the codes according to whether they represent site characteristics, sample properties, major inorganic constituents, minor inorganic constituents, nutrients, radiochemicals, stable isotopes, industrial organic substances, agricultural organic substances, natural organic substances, biological taxa or biological properties. With minor exceptions, parameter codes assigned to a particular General Physical/ Chemical Grouping can also be assigned to any one of the Sample Medium Groupings. The third level in the hierarchy is called the Specific Physical/Chemical level and consists of 436 more specific physical and chemical groupings. A parameter code assigned to a particular Specific Physical/Chemical Grouping is assigned to an appropriate General Physical/ Chemical Grouping and Sample Medium Grouping, based on the information supplied in the parameter code description. Each parameter code has been assigned a three-part seven-digit integer indexing code that incorporates the three-level hierarchy.