Document Type


Publication Date

January 1967


Background of Program: In devloping a water resources atlas for the State of Utah, numerous stream flow records were analyzed to determine their flow characteristics. The objective was to present the results in a format which is well adapted for use by water resources planners in preliminary designs to obtain optimum benefits from the water resources. The program described in this booklet was written to determine the probable amounds of storage required in order to meet specified levels of sustained demand for water. The method used not only gives information concerning amounts of storage but also information concerning the probably amounds of excessive flows taht might be used for this storage, both of which are a function of the period of carry over and the recurrence interval and have been referred to hereafter as a frequency mass curve analysis. The procedures and techniques used are described later. In addition to the frequency mass curve analysis the program also determines the probable variation of the streamflow for each month of the year and the annual flow. By examining the amounts for the twelve months at any probability level the variation of streamflow throughout the year is obtained. These probable variations, or frequency analyses, are obtained by fitting the data to any of all of the following four distribution functions: 1. Normal, 2. Ranking in order of decreasing magnitude, 3. Gamma, and 4. Log-normal. The analyses leading to the frequency mass curves generates a new sequence of data whose ditribution is obtained in the program discussed herein by ranking the data from largest to smallest. The necessary parameters are computed to fit the data to a normal distribution, and with relatively minor modifications any other distribution, such as a gamma or long-normal may be used to fit this data. The subsequent analyses leading to the storage requirements would be unaltered. This booklet is one of a series which contains FORTRAN programs written for specific purposes at the Utah Water Research Laboratory, which are considered of general enough use by other individuals or agencies to justify a brief description and listing of the program with a sample of the output.