Surface-water hydrology is the study of the origin and processes of water in streams and lakes, in nature, and as modified by man. It includes such subjects as infiltration, channel storage, floods and droughts, direct runoff, and base flow. Surface-water hydrology shares with meteorology the study of precipitation and evaporation. Also, surface-water hydrology shares with geomorphology the study of the shape, size, and number of river channels, because river channels are formed as a consequence of the rates and quantities of water they must carry. Some of the tools used in the study and application of surface-water hydrology are unit hydrographs, flow-duration curves, flood-frequency curves, and correlation, all of which are defined in this report.

The definitions in this list are intended to explain the terminology in the “Manual of Hydrology” of which this report is the first chapter. It is, however, more than a glossary of terms used in the manual, as terms are included from the entire field of surface-water hydrology. Terms within some of the definitions are defined in this chapter. Where such terms might affect the meaning of the definition, they are shown in italics.

Excluded from the list are such terms as “river,” “lake,” “creek,” and other names for surface-water features, for which hydrologists have not devised better definitions than are in the dictionaries. In general, therefore, common dictionary terms such as “anomaly” or “abnormal” are not included–but there are exceptions–where a term, like “anabranch,” deserves wider usage. Also excluded are those terms, although often used in surface-water hydrology, that are mainly geologic, hydraulic, statistical, or meteorologic. These terms are defined, as necessary, in separate chapters.

The usefulness of a list of definitions is limited by the extent to which the concepts they embody are accepted. To enhance precision and to promote agreement, many of the definitions listed were selected from research papers or reports on field investigations to which appropriate reference is given. Multiple references are cited where they amplify the meaning, and these references can be used as a source of additional information on surface-water hydrology. Where acceptable definitions could not be found in published works, substitutes were written especially for this chapter. Terms defined in this report are grouped by subjects in the section entitled “Topical finding list” to facilitate locating the definitions of related terms.

Walter B. Langbein selected or composed the definitions presented in the report, and Kathleen T. Iseri arranged the report for publication, verified references, and prepared the topical finding list. 


reference: USGS – Water Basics Glossary