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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />CORRELATION STUDIES <br /> <br />A number of correlations between streamflow records of different gaging stations <br />were conducted. The list includes correloting records of stations within the Gunnison <br />basin with each other, plus correlating with stations outside Gunnison basin. Table 9 <br />shows a summary of these correlations including stations correlated with each other, per- <br />iod of historical data used in correlation and the coefficient of correlation obtained. <br />Also, this table presents those correlations utilized to extend the historical data. An ex- <br />ample of these correlation studies is presented in the Appendix. <br />From the recorded and extended data for a number of stations, analysis of the <br />data by statistical distribution was performed. Table 10 shows the data utilized in fre- <br />quency analysis to determine flows for different frequencies at respective locations. <br />This table also differentiates between the recorded and extended data. <br /> <br />FREQUENCY DISTRIBUTION <br /> <br />All cumulative frequency distributions were performed by utilizing the Log <br />Pearson Type III method, as suggested by the United States Water Resources Counci I bul- <br />letin Number 15, "A Uniform Technique for Determining Flood Flow Frequencies", and <br />additional K values received from U.S. Soil Conservation Service for reC\1rrence interval <br />greater than 200 years. <br />This procedure has some advantages over other frequency distribution methods. <br />This is one of the few methods which takes into account the third moment about the mean <br />(skew). This generally allows for a better fit as it gives the extremes of a positive or neg- <br />atiVE: curvature. However, the skew coefficient is a very sensitive parameter which is <br />greatly effected by extremes. It is conceivable that a given station could have a posi- <br />tive skew whi Ie another station, slightly downstream, could have a negative skew. This <br />could result in extreme flows on the downstream station being less than those of the up- <br />stream station. Certain procedures would need to be taken to overcome this problem, <br />should it arise. <br /> <br />-6- <br />