DSpace Community: Department of Civil and Environmental Engineering

Double-Mass Curves

Thu, 29 Oct 1959 22:58:59 GMT

Title: Double-Mass Curves

Authors: Searcy, James K.; Hardison, Clayton H.

Abstract: The double- mass curve is used to check the consistency of many kinds of hydrologic data by comparing date for a single station with that of a pattern composed of the data from several other stations in the area. The double-mass curve can be used to adjust inconsistent precipitation data. The graph of the cumulative data of one variable versus the cumulative data of a related variable is a straight line so long as the relation between the variables is a fixed ratio. Breaks in the double-mass curve of such variables are caused by changes in the relation between the variables. These changes may be due to changes in the method of data collection or to physical changes that affect the relation. Applications of the double-mass curve to precipitation, streamflow, and sediment data, and to precipitation-runoff relations are described . A statistical test for significance of an apparent break in the slope of the double-mass curve is described by an example. Poor correlation between the variables can prevent detection of inconsistencies in a record, but an increase in the length of record tends to offset the effect of poor correlation. The residual-mass, curve which is a modification of the double-mass curve, magnifies imperceptible breaks in the double-mass curve for detailed study. Of the several methods of fitting a smooth curve to cyclic or periodic data, the moving-are method and the double-integration method deserve greater, use in hydrology. Both methods are described in the manual. The moving-arc method has general applicability, and the double integration methods is useful in fitting a curve to cycles of sinusoidal form.

A Study of the Pollution and Natural Purfication of the Ohio River

Tue, 29 Oct 1957 22:58:59 GMT

Title: A Study of the Pollution and Natural Purfication of the Ohio River

Authors: Streeter, H.W.; Phelps, Earle B.

Description: The studies presented in this report were made by the United States Public Health Service during the years 1914 and 1915 as part of a comprehensive survey of the pollution and natural purification of the Ohio River, conducted under the supervision of Surg. W.H. Frost. The scope and purposes of this survey as a whole are outlined in a previous publication, to which reference is made for a detailed description of the Ohio River, summaries of its sources of pollution, and measurements of discharge and velocity, also for presentation and discussion of the results of bacteriological examinations and chemical analyses other than those dealing with observations on dissolved oxygen. These latter observations, which are presented in the previous publication only in the form of a basic summary without discussion, are regarded as being sufficiently distinctive in their significance and in the character of analysis required to justify their separate treatment in this supplementary report.

Biological Implication of Metals in the Environment

Fri, 29 Oct 1976 22:58:59 GMT

Title: Biological Implication of Metals in the Environment

Authors: Drucker, Harvey

Description: Proceedings of the Fifteenth Annual Hanford Life Sciences Symposium at Richland, Washington, September 29-October 1, 1975.

Reservoirs in the United States

Fri, 29 Oct 1965 22:58:59 GMT

Title: Reservoirs in the United States

Authors: Martin, R.O.R; Hanson, Ronald L.

Abstract: This report summarized the storage capacities and related data of reservoirs and controlled natural lakes for the conterminous United States, Alaska, Hawaii, and the Commonwealth of Puerto Rico. Data are given for all storage facilities having a usable capacity of 5,000 acre-feet or more and completed or under construction as of Jan. 1963. A descriptive list of reservoirs in the United States completed as of Jan. 1, 1947, was first published (Geol. Survey Circular 23) in March 1948. In 1956 Water-Supply Paper 1360-A, "Reservoirs in the United States," by N.O. Thomas and G.E. Harbeck Jr., updated this listing and included lists of reservoirs completed or under construction as of Jan. 1, 1954. Some of the data shown for reservoirs constructed before 1954 may have been corrected herein on the basis of the latest available reservoir survey. This report list 1562 reservoirs and lakes; their useable storage totals 359,360,000 acre-feet, and the corresponding surface area in 14,831,000 acres.