Laserfiche WebLink
<br />.J <br />~ :1 <br />-J <br />I <br />:.\ <br />.. <br /> <br /> <br /> <br />1 <br />] <br />J <br />J <br />1 <br />J <br />j <br />I <br />] <br />'.-1 <br />.' <br /> <br />23 <br />determined for several rivers which have flow records before and after a <br />dam was constructed. Thirdly, flow records for the Colorado River near <br />the study area were analyzed to determine the effects of upstream water <br />development. All gauges used in the analysis are on ~ivers that are <br />snowmelt driven, and most records extend at least into the 1930s. <br />Trends in streamflow were identified by analyzing both peak and <br />mean flows throughout the period of record. Since the majority of water <br />development in the upper basin occurred after 1950 (Figure 3.1), flows <br />were divided into a pre-development (1900-1949) and post-development <br />(1950-present) period. For each gauge, the mean peak and mean annual <br />flow for both periods was calculated, and a mean hydrograph was <br />constructed to illustrate differences in the magnitude and duration of flow <br />between the two periods. The significance of changes between the two <br />periods were determined using aT-test. The mean hydrograph was <br />created by summing the mean daily discharge each day throughout the <br />period, and dividing it by the number of years of record. <br /> <br />Unregulated Rivers <br />There are three unregulated rivers in the region that have flow <br />records which extend into the early part of the century. These rivers are <br />the East River at Almont, the Yampa River near Maybell, and the <br />Uncompahgre River at Colona (Figure 3.2). Some water diversions are <br />present which may affect flows during the irrigation season, but in general <br />they have a natural flow regime. <br />