Laserfiche WebLink
Discharge.-- <br />PLATTE RIVER BASIN <br />06714000 SOUTH PLATTE RIVER AT DENVER <br />Location.-- <br />Drainage and Period of Record.-- <br />Lat. 39°45'35",Long. 105°00'10", in NW¼SE¼ sec. 28, T.3 S., R.68 W., Denver County, Hydrologic Unit 10190003, on right <br />bank 90 ft Upstream from Nineteenth Street Bridge in Denver and 0.4 mi downstream from Cherry Creek. <br />3,861 mi². May 1889 to Oct. 1890 sporadic record. July 1895 to current year continuous. Monthly data only for <br />some periods. <br />The shelter is 72 inch by 72 inch precast concrete structure with a 48 inch corrugated steel well. The station uses an <br />electric drop tape, Sutron 8210 satellite telemetry with a phone modem interface (not currently used), a continuous chart <br />recorder and a supplemental outside wire weight. A city water line is plumbed to the gage for flushing the inlets. USACE is <br />a cooperator on the gage, and UDFCD has Alert instrumentation installed. Additionally, the UDFCD contracts with the <br />USGS to operate a water quality sampler there. <br />Equipment.-- <br />Hydrographic Conditions.-- <br />Gage-Height Record.-- <br />Datum Corrections.-- <br />Rating.-- <br />Discharge.-- <br />Special Computations.-- <br />Remarks.-- <br />Recommendations.-- <br />The primary record is hourly averages of fifteen minute data taken from satellite monitoring with chart backup. Daily <br />maximum and minimum stages for the satellite record checked to within +/- 0.02 ft with the chart. Missing satellite data on <br />November 23, 2008, March 8, and June 26, 2009 were filled in with chart data with no loss of accuracy. The record is <br />complete and reliable. <br />Levels were run on September 24, 2009, but were inconclusive due to conflicting readings from R.M. #1 and R.M. #2. No <br />correction was made at that time, and levels will be run again in the spring. Reference Marks #7 and #8 were also added <br />to increase accuracy as RM# 2 has possibly moved. <br />The control is a rock gabion dam approximately 50 feet below the gage. Rating No. 34 was developed this year and was <br />begun in use on October 1, 2008. It is defined by measurements from 39.4 to 5340 cfs. Rating No. 34 was extended to <br />12,600 cfs using a peak flow on July 25, 1998 that was indirectly calculated using records from downstream gages. <br /> Seventeen measurements (Nos. 968-984) ranging in discharge from 93.3 to 1370 cfs were made this year. These cover <br />the range in stage experienced, except the higher daily flows of April 18; April 27; May 24-26; June 2-14; and July 4, 2009. <br /> The peak flow of 5260 cfs occurred at 0030 on May 26, 2009 at a gage height of 8.13 ft with shift of 0.00 ft. It exceeded <br />measurement no. 977, made on June 12 by 3.01 ft. Peak flow at this gage usually defies measurement — often occurring <br />as a sharp, transitory rise at night. <br />Shifting control method was used all year. The channel has a sand bottom and is continually scouring and filling as flow <br />passes through the gabion control. The control slows and deepens the flow. Sustained periods of high flow at this gage <br />will cause positive shifts, indicating scour. TMeasurements show unadjusted shifts varying between -0.01 to +0.04 feet. <br />All measurements were given full weight, except No. 974 which was adjusted -3% to smooth shift distribution, and No. 977 <br />which was adjusted +1% to zero to the new rating. Shifts were prorated by time with consideration given to stage for the <br />entire period of record. Each storm event was analyzed to verify that the peak flow had a shift that was consistent with any <br />possible stage distribution. <br />The “spill”, as added to some of the measurements in the past, is the regulating discharge from the Farmers and Gardeners <br />Ditch. The spill is just upstream and across the channel from the gage. The ditch and associated Parshall flume are <br />covered and buried, so the spill emerges from a culvert. Normally there is no place below the spill where a good <br />measurement can be made, so upstream measurements are made with this “Spill” added to the total. There wasn’t any <br />spill during measurements this year. It is impossible to actually measure the spill since it shoots out from under a gate <br />down and sluices down to the river. Velocities are supercritical and the flow has air in it. Often 10 cfs is estimated, based <br />on a ditch rider statement that the headgate will take a maximum of 35 cfs from the river and the ditch is decreed at 24 cfs. <br />At low flow, this estimate can have a significant effect on measurement accuracy. Extreme low flow measurements have <br />been made downstream of the Farmers and Gardeners Ditch spill and just upstream of the control pool. Normally this <br />section is too deep to wade. <br />The record is considered good. Station maintained and record developed by Jana Ash. <br />Run levels in the spring of 2010 and summarize past observations in a levels summary spreadsheet. <br />2009Water Year