Laserfiche WebLink
G – Bi-seasonal HCI Relationships <br />A portion of this project was dedicated to briefly examine the potential of using <br />HCI values in a ‘multi-seasonal’ format to assess the potential utility of this information. <br />The variables that were looked at were the 2 consecutive year aggregate seasonal winter <br />(Dec-Mar) and spring (Apr-Jun) precipitation values in addition to the peak seasonal <br />runoff (Apr-July or September depending on the basin). All of the 2-year aggregate <br />seasonal values are compared to the leading values of the HCI variables before the first of <br />the two-season comparison. Given the multi-seasonal relationship of the observed <br />variables, the descriptions of the relationships will be more generalized, in nature than the <br />prior sections of the report. <br />Winter (Dec-March) Precipitation: <br />In Districts 20 & 26 there appears to be some connections on the bi-seasonal basis <br />with El Nino and negative AMO conditions favoring a higher value of precipitation in the <br />overall basin. For District 35, the very robust single-seasonal relationships with the <br />ENSO/NAO and AMO bleed over into the same relationship values as the single seasonal <br />values. <br />Spring (Apr-Jun) Precipitation: <br />For all Districts, the leading ENSO index is considered to clearly be the leading <br />indicator of multiple-spring precipitation values. The AMO has a weaker relationship <br />however; the ENSO is the recommended index for proposed user analysis. <br />Spring/Summer Runoff: <br />In Districts 20 & 26 the use of the AMO Index as a ‘leading’ indicator is <br />becoming quite apparent across many basins and this is no exception. The AMO, albeit <br />relatively ‘new’ in its appearance in scientific literature is a very important multi-year <br />delineator of potential runoff. The ENSO indicies also exhibit some non-random <br />variation which could help in refining two-year outlooks as well. <br />For District 35, the very robust single-seasonal relationships with the AMO and <br />ENSO are notably stronger than the NAO (the NAO has a higher season-to-season <br />variability than ENSO/AMO). However, ENSO is a net stronger single component with <br />the AMO being a more ‘secondary’ index. <br />Division 7 (San Juan/Dolores) <br />Division 7 (called the San Juan/Dolores) is more commonly thought of as part of <br />the southwest mountains where the runoff from major streams in the region flow into the <br />main stem of the Colorado outside of state line. In the case of the Dolores River the river <br />meets the main stem of the Colorado in Utah and the San Juan River (which collects the <br />18 <br />