ISSN:0020-6024    

DOI:10.1080/02626667109493781

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

ISSN:0020-6024    

DOI:10.1080/02626667109493782

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

ISSN:0020-6024    

DOI:10.1080/02626667109493783

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Accumulations of snow behind fences may increase the water yield in windswept areas. The efficiency of snow collection depends on the reduction in wind speed in the lee of the fence. Wind speeds have been measured to windward and to leeward of vertical slat fences from 6 to 16 ft. high. The down-wind measurements were made at distances of 2.5H, 5H and 10H from the fence where H is the height of the fence. Speed measurements at various levels were integrated up to the height of the fence and the percentage reduction in wind speed was calculated. Expressions are given for the velocity reduction factor at distances down-wind of fences having a bottom gap, and for the cross-sectional area of a fully developed drift.

ISSN:0020-6024    

DOI:10.1080/02626667109493784

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

In statistical hydrology, three different methods have been used to calculate the expected values of observable quantities in an ensemble. The first is to use an observable as a parameter to characterize the “states” of the ensemble and then to calculate the average value of the observable over all possible states; this is the expected value. The second method is to use an observable as a parameter to characterize the “states” and then to designate the most probable value of the observable as the expected value; this is known as the “minimum variance principle”. Finally, the third method is to use a parameter different from an observable to characterize the “states” and then to take the value of the observable for the most probable state as the expected value. Of all these different methods, only the first one is, in principle, physically correct. Thus, a study was made to determine the situations where methods other than the first can be used to calculate the expectation values of observables. It was found that this can be done only in those situations where all of the following conditions hold: (i) The number of parameters used to characterize the states is finite; (ii) these parameters are either the same as the observables or are explicitly related to the observables; and (iii) each of the parameters has a symmetrical and unimodal probability distribution. The cases where the minimum variance principle is valid, are thereby delineated.

ISSN:0020-6024    

DOI:10.1080/02626667109493785

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

There is no universally acceptable technique available to estimate the magnitude and frequency of floods. The “rational method”, empirical formulae and regional analysis all have restrictions.

ISSN:0020-6024    

DOI:10.1080/02626667109493786

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

A test is presented to reveal automatically doubtful water levels and to detect sudden or gradual modifications of the stream flow.

ISSN:0020-6024    

DOI:10.1080/02626667109493787

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Water-borne, fluorescent tracers are conventionally detected by fluorometrically analysing liquid samples taken discretely or continuously from the water body under test. A continuous, automatic, film system described here detects tracer concentrations of one part per billion (1 in 109), provides a time distribution of concentration changes, and combines low cost with ready portability. Field installations are self-operative for up to ten days. A single laboratory-based fluorometer can easily analyse the concurrent data input from fifteen or more field installations. Data can also be stored prior to fluorometry. Fluorescent tracers have been detected successfully by the film system under experimental conditions to gauge streamflow, to produce flow hydrographs, and to determine the travel time of streamflow. Further refinements should be made by potential users to optimize the system for specific needs.

ISSN:0020-6024    

DOI:10.1080/02626667109493788

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

ISSN:0020-6024    

DOI:10.1080/02626667109493789

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

ISSN:0020-6024    

DOI:10.1080/02626667109493790

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor