Laserfiche WebLink
Calculations of Base Flows : Base flow calcu- <br /> • lations were made for all drainage basins contributing to <br /> the Crystal River between the Placita (#9-0815 . 5) and <br /> Avalanche Creek (#9-0816) gauging stations . Figures III-E-5 <br /> and III-E-6 show the drainage basins and perennial and <br /> intermittent streams respectively . Table III-E-5 lists the <br /> corresponding drainage basins and their areas . Calculations <br /> for base flow were made using published USGS data for the <br /> years 1960 through 1969 . <br /> The Crystal Creek gauges , (#9-0815 . 5) and <br /> (#9-0816) , are approximately 72 miles apart and discharge <br /> records are available for both stations for 1959 through <br /> 1970 . Assuming a minimum flow velocity of 2-3 ft/sec . , the <br /> flow time between gauges is about 52 hours . Thus there <br /> should be very little "lag" in increases or decreases in <br /> flow. The minimum inflow between the gauges ranges from 1- <br /> cfs to 6-cfs . These are the lowest flows during the year <br /> and the average base flow is approximately 10-cfs to 12-cfs . <br /> Base flows for individual years were estimated using average <br /> low flow for the November to March periods for each year . <br /> This time period was used because snow is the predominant <br /> precipitation with very small amounts of runoff . <br /> The estimated average base flows were sub- <br /> tracted from the annual flow, resulting in values for total <br /> runoff for each particular year . Rainfall records for the <br /> Aspen, Colorado area were evaluated , however , a precipita- <br /> tion map of Colorado was used to determine the average <br /> 31 <br />