摘要:

Problems of flood‐control increase in urgency of solution with more intensive use of land. The Omnibus Flood Control Act of 1936 (Public H. R. 738, 74th Congress) represents an important forward step on the part of the Federal Government to work out with States and Districts ways of alleviating flood‐damage and of retardation of storm‐runoff from its beginning in unabsorbed raindrops to raging rivers. The gathering grounds of flood‐waters become as much a part of the problem as the flood‐ways of the trunk‐streams. In short, the science of hydrology is called upon to furnish the information necessary to a vast and vital undertaking in the use and protection of land‐ and wa

ISSN:0002-8606    

DOI:10.1029/TR019i001p00508

年代:1938

数据来源: WILEY

摘要:

From a series of measurements made in the 12‐foot wide rectangular flume at the National Hydraulic Laboratory, National Bureau of Standards, information was obtained in regard to the distribution of velocities in a cross‐section with respect to the manner in which the velocities near the sides differed from the velocities in the central part of the flume, also in regard to the variations in velocities from point to point in the vertical depth. This information was used in connection with the laboratory‐project conducted by the Water‐Resources Branch of the Geological Survey in the investigation of current‐meter performance in measurements of the velocity of water in shall

ISSN:0002-8606    

DOI:10.1029/TR019i001p00517

年代:1938

数据来源: WILEY

摘要:

A knowledge of the variability of precipitation‐averages for periods of various lengths is essential for the correct use of rainfall‐data. First, it must be known what length of record is needed to yield an average which may be projected into the future within tolerable limits of error. Second, the magnitude and frequency of departures from the average—particularly negative ones—must be considered in various practical problems such as providing storage, selecting sources of supply, and determining the economic extent or feasibility of projects which depend in any way upon amount of rainfall.Previouswork—The pioneer study by Binnie [see 1 under “References” at end of paper] on the variability of rainfall is widely quoted in current texts on hydrology, water‐supply, and waterpower. This early work was based primarily upon precipitation‐records from 26 stations in various parts of the world, the annual totals at each station being expressed as percentages of the

ISSN:0002-8606    

DOI:10.1029/TR019i001p00520

年代:1938

数据来源: WILEY

摘要:

A very urgent need exists among hydrologists and engineers for the best possible measure of the average frequency of high‐intensity rainstorms. This is a particularly difficult determination for those intense storms for which the average length of time between occurrences is as great or greater than the average length of rainfall‐records. The station‐year method was proposed for the estimation of the average frequencies of such storms for any area, from a long synthetic record built up from many short records for stations in the

ISSN:0002-8606    

DOI:10.1029/TR019i001p00526

年代:1938

数据来源: WILEY

摘要:

In the very brief period that I have the right to impose upon the time of this meeting, there is only opportunity for a hurried review of some of the progress that has been made during the last year. It is impossible to go into theory, interesting as it may be, as the time can best be spent in giving a glimpse of the many facets of the general problem of getting the most out of our past rainfall‐records. In the first place the detailed results of the study of rainfall in the Susquehanna Valley are now available in the Transactions of the Pennsylvania Electric Association for the year 1937. This report summarizes tne analysis of some 200 rainfall‐stations, and presents a revised map of rainfall, together with a table of estimated average rainfall for tne entire area by years back to 1

ISSN:0002-8606    

DOI:10.1029/TR019i001p00529

年代:1938

数据来源: WILEY

摘要:

In all investigations involving precipitation‐records it is of the utmost importance that the basic data accurately represent conditions that obtained through the years of record. Under the climatological service of the Weather Bureau, where observations are taken on a cooperative basis at literally thousands of stations, and through which millions of records have been collected and summarized during the past half century, we naturally would expect to find, here and there, some erroneous data, resulting possibly from faulty gage‐exposure, lack of comparability through changes in gage‐location, and even errors chargeable to the personal equation in observational work. While it is recognized that such basic errors do exist, it is believed that they are generally of much smaller magnitude and not nearly so frequent as some investigators have been led to believe. We believe in most cases that sharp changes in rainfall‐trends are due to natural

ISSN:0002-8606    

DOI:10.1029/TR019i001p00533

年代:1938

数据来源: WILEY

摘要:

The aim of a precipitation‐gage is to obtain a sample of the rain or snow that falls on to the ground. Thus, a gage with its orifice flush with the ground would be ideal were it not for the splash from the ground near by, the drifting of snow, or occasional floodings or burying. The splash can be eliminated by surrounding the gage with a sufficiently extensive surface of honeycomb or brush or fine wire‐netting; but the drifting of snow and flooding or burying can be only partially controlled, and with difficulty. So, the standard practice is to elevate the orifice of the gage above the splash (one foot) or above most of the drift (three or more feet). But this introduces a new problem: the disturbance of the falling precipitation, especially when snow, by the wind‐eddies over the

ISSN:0002-8606    

DOI:10.1029/TR019i001p00539

年代:1938

数据来源: WILEY

摘要:

Satisfactory shields and enclosures for the standard United States Weather Bureau type of rain‐and‐snow gage are essential to the accurate measurement of precipitation by gages placed in open areas. By using a limited number of widely distributed gages, it is usually possible to place them in properly sheltered sites. However, when the number and distribution‐density of the gages are increased, it is often extremely difficult to find suitable exposures.In connection with the watershed‐studies being conducted by the Soil Conservation Service of the United States Department of Agriculture near Coshocton, Ohio, where rain‐and‐snow gages are distributed at intervals of about one‐third mile over privately owned watersheds of several thousand acres area, many gages are necessarily exposed directly to wind‐action. In order that equipment may be developed for improving the catch of gages so exposed, an experimental plot has been established in the watershed‐area and equipped with several standard rain‐and‐snow gages on which various types of shields and enclos

ISSN:0002-8606    

DOI:10.1029/TR019i001p00542

年代:1938

数据来源: WILEY

摘要:

The variation of rainfall‐intensity expected for a given frequency with season of the year is an important factor in estimation of runoff from small drainage‐areas such as those tributary to erosion‐control dams. Calculations of probable runoff‐rates in Wisconsin are ordinarily based on two assumptions, namely, (1) rainfall of maximum intensity will occur in mid‐summer and (2) the maximum runoff from a small area will result from rainfall of maximum intensity.To check, the reasonableness of these assumptions for Wisconsin conditions, intensity‐frequency studies by months were made of the complete records of six United States weather Bureau stations located at Milwaukee, Madison, La Crosse, Wausau, and Green Bay, Wisconsin, and Duluth, Minnesota, located as shown on Figure 1. Storms were grouped by months, the records for all stations for any month being combined into a single record of 204 st

ISSN:0002-8606    

DOI:10.1029/TR019i001p00550

年代:1938

数据来源: WILEY