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<br />Long Term Monitoring - Channel Morphology <br />Fiscal Year 2001 Project Proposal <br /> <br />Principal Investigator: Ron Bliesner <br />Keller-Bliesner Engineering <br />78 East Center, Logan, UT 84321 <br />(435) 753-5651 bliesner@kelbli.com <br /> <br />Stud v Area: <br /> <br />The study area consists of the San Juan River and its flood plain from RM 180 (Farmington, NM) to RM 3 <br />(Clay Hills Crossing). <br /> <br />Collections: <br /> <br />There are no collections associated with this study. <br /> <br />Backeround: <br /> <br />There are presently 25 river transects that have been established between RM 180 and RM 3 in the San Juan <br />River for purposes of measuring channel scour and deposition. Additionally, substrate composition (sand or <br />cobble/gravel) has been identified during each survey, These cross-sections have been surveyed before and <br />after runoff since 1992. The data from these surveys was used to examine channel scour and deposition, <br />determine change in channel capacity and track change in substrate material. Flow statistics for 8,000 cfs flows <br />were based, in part, on these data. <br /> <br />Maintenance of cobble bars with open interstitial space has been determined to be important for spawning of <br />Colorado Pikeminnow. Four of the sites (RM 173.7, 168.4, 132, 131) that have been identified in the San Juan <br />River as having characteristics suitable for spawning have been monitored since 1995. The results of the <br />surveys at this site were used as part of the basis of the flow recommeridation at 8,000 cfs. To verifY or adjust <br />this reconunendation, these sites will continue to be monitored, <br /> <br />The flow-habitat area model for backwaters is based on the ability of the channel to clean sediment from the <br />system and the rate at which the sediment accumulates in the backwaters after runoff. The amount of <br />perturbation (loss of habitat) due to summer and fall storms has been estimated based on analysis of habitat area <br />data collected before and after stoml events. Equivalent data on change in depth of backwaters and depth of <br />sediment have not been analyzed. It is proposed that sediment depth and water depth be measured in <br />backwaters twice yearly at the end of runoff in late July or early August and again in October to assess change. <br />The second sampling will be completed during the fall habitat mapping exercise, <br /> <br />20 <br />