WSP07062 - Laserfiche WebLink

Home Browse Search

8 The linear regression equations as derived from the 31 years of . data are shown below: Correlation " Month Equation Coefficient January Outflow = 0.90 Inflow + 12, 81 (I 0.91 February Outflow = 1.13 Inflow + 7, 69~~ . 0.97 March Outflow = 1.07 Inflow + 7,340 0.98 . Apr II Outflow = 1.03 Inflow + 1,900 0.99 May Outflow = 1.18 Inflow 29,660 0.99 June Outflow = 1.05 In flow 25,150 0.98 July Outflow = 0.91 Inflow 21.290 0.98 .' August Outflow = 0.81 Inflow 10,670 0.93 September Outflow = 1.19 Inflow 8,100 0.99 Oc tober Outflow = 1.13 Inflow - 1,040 0.98 November Outflow = 1.13 Inflow + 1,280 0.97 December Outflow = 1.19 Inflow + 7,360 0.97 Wa ter Year Outflow = 1.08 Inflow 58,120 0.99 1\ noticeable feature of the regression equiltions is that the coef- ficient of the inflow term is nearly uni ty for most months. Thus, the constant term in eilch equation is a fair index of the ilverilge net gain or depletion of water in the Henderson to Kersey reach of the South Platte River. " Comp<lrlson of Inflows anel Gqmputed R~.1urnJ1Q~ " Inflows were cillculated as explilined in the preceeding section. Return flow.was computed in the following milllner: (a) Total diversions for irrigation between the Henderson and Kersey gages + (b) Discharge of the South Plotte River near Kersey - (c) The measured inflows below the Hen- derson goge. The analyses were made using identical time periods' and pro- cedures as those of the previous section. The following results were'ob- tained from these analyses. 1. The observable trend changes, based on the double-mass plot analysis, are generally rather mild, On an annual basis there was a decrease of return flows in the period of 1951 to 1962 as compared to the relationship from 1936 to 1951. The relationship between inflow and return flow has been nearly the same as the 1956 to 51 period since 1962. On a monthly basis the same pattern is observed for Ap~il, May, June, September and October. During July and hUgust a relative decrease in return flow can be observed during the recent four years. In some months the relationship has recently been returned to the original, but this has not occurred in November and December. The winter reduction in return flows may be caused by water going to storage into the alluvium. Despite the changes in trend, the influence on annual return flow is small because the winter flows are small in comparison to that of other months.