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Figure 9. Relationship between the NAO and a summation of naturalized stream flow in Costilla <br />County (District 35). <br />F - Single Seasonal Runoff Timing <br />The timing aspect of the runoff in the basin was examined by looking at the <br />comparison of the Julian Date of the 50% point of the April-July peak seasonal flow <br />verses the HCI values. For reference the Julian Date is the numerical day of the year <br />strd <br />after January 1; for example February 3 is Julian Day 34 (31 January days plus 3 days <br />in February). Before this was performed , it was necessary to determine the relationship <br />of the date of 50% flow and the actual volume of that year. It should be noted that the <br />period of record available for the daily naturalized stream flow data in this Division is <br />1969-2002 thus limiting the data points available for analysis. In the case of the flow at <br />Del Norte, the overall relationship between the 50% seasonal flow mark and the volume <br />was significant enough that we examined the residual (or in effect taking out the effects <br />of volume) to determine the seasonal effect. The result was that there was that only <br />AMO (positive = earlier runoff mid-point) appeared to have some impact however, in <br />looking at the individual relationships with the AMO correlation charts, this impact did <br />not appear to be as clear therefore we do not recommend any use of HCI to foresee runoff <br />timing from the seasonal standpoint without further investigation at a later time or by the <br />user. <br />17 <br />