Laserfiche WebLink
<br />'., 11 1 / ''-) <br />[j (j ... 't 't ( <br /> <br />. <br /> <br />-3- <br /> <br />. <br /> <br />, <br /> <br />I. .PROBABILITY ANALYSIS OF STREAMFLOW ~ <br /> <br />Probability analysis is a statistical and mathematical process for de- <br /> <br /> <br />termining the probable occurrence of a given phenomenon based on observation <br /> <br /> <br />of the previous occurrence or occurrences of that phenomenon. Several types <br /> <br /> <br />of analysis of probability have been developed which are applicable to various <br /> <br /> <br />tyPes of phenomena. The most cOlDJDon type of analysis is the so-called "normal <br /> <br />frequency distribution" type. This is mainly applicable to events whose ooour- <br /> <br /> <br />rence is not related to time. The presence of the time factor, as in a series <br /> <br />of annual streamflow, usually requires the analysis of the possibility of se- <br /> <br /> <br />quential correlations or linkages of two or more years within the total series. <br /> <br /> <br />The Colorado River data will be tested for randomness and for linkage. <br /> <br />'i <br /> <br />Public Law 485, Section 6, requires that certain financial data relative <br /> <br /> <br />to the Colorado River storage Project be reported to Congress on January)l of <br /> <br />each year commencing in 1958. Basic to such a report is the relationship of <br /> <br /> <br />anticipated power revenues to the financial requirements of the Act. In turn, <br /> <br /> <br />the anticipation of power revenues involves assumptions and premises as to <br /> <br />future hydrologic conditions and as to water passing the storage dams to down- <br /> <br />stream uses. <br /> <br />Accordingly, the Bureau of Reclamation and the various states of the Upper <br /> <br /> <br />and Lower Basins are engaged currently in studies to determine the financial <br /> <br /> <br />results of various operotions procedures. Such operations procedures are de- <br /> <br />rived from assumptions concerning such items as stream flow, initial storage <br /> <br /> <br />in Lake Mead, downstream water requirements and existing power contracts at <br /> <br /> <br />Hoover. <br /> <br />The original working hypothesis of the Bureau of Reclamation (1957) <br /> <br /> <br />assumed a stream flow of 13.1 million acre feet per year for a number of years <br /> <br />sufficient to fill Glen Canyon. Others, including the state of California, <br /> <br /> <br /><have made use of the historical flow of record, assuming 1922 to represent 1962, <br /> <br />1923 to represent 1963, etc. No doubt other assumptions have been utilized in- <br /> <br /> <br />volving, perhaps, an arbitrary series of years of high flow or low flow. <br /> <br />It should be recognized that studies based upon such arbitrary assumptions <br /> <br /> <br />of stream flow are of limited usefulness, since they have no established pre- <br /> <br />dictive value. Obviously what is needed is an approach to this problem which <br /> <br /> <br />can replace arbitrary assumptions about stream flow with scientific prediction. <br />