9534 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I sand/silt fraction and 30 of the box samples will be analyzed for concentration only. The cross-section samples will be collected for purposes of developing a coefficient to. relate the box samples to the total suspended sediment load in the river. 5. A 1-year program of sediment-load measurements, including both suspended-and bed- load, and bed-material sampling will be conducted at an appropriate site near the head of Lodore Canyon on the Green River. 6. A 1-year sediment monitoring program will be conducted near the confluence of the Green and Yampa Rivers to establish the relationship between sediment load and discharge in the two rivers, and to define the sediment load discharge from Lodore Canyon during high flows. Three sampling sites will be established for this task: lower Yampa River just upstream from Echo Park, Green River just upstream from the Yampa River confluence, and Green River in Echo Park downstream from the confluence. The following data will be collected at each location (minimum 10 sets per year): . Sediment load measurements, including suspended sediment and bed load . Bed material samples . Discharge measurements . One cross-section survey 7. A channel-monitoring program will be established to document the morphological response of the river to high flows in the Green River, particularly as they are affected by future jet tube releases from Flaming Gorge Dam. Four reaches have been identified for this program: . Rainbow-Island Park reach (6 to 10 cross sections) . Razorback sucker spawning bar and Escalante reach (6 cross sections) . Ouray Wildlife Refuge reach (6 to 10 cross sections) . Canyonlands reach (2 or 3 cross sections) New cross sections will be established and monumented at the Rainbow-'Island Park reach, and existing cross sections would be utilized at the remaining reaches. To identify the changes that result from the high-flow runoff,cross sections should be surveyed at each reach at least 3 times during the year, with the first survey prior to the peak discharge (probably early April), the second survey at or near the peak (late May), and the third after passage of the snowmelt hydrograph (August or September). All 4 sites will be surveyed during the initial year of the program to establish the baseline condition. The Razorback spawning bar and Rainbow-Island Park reaches will be re-surveyed on an annual basis for 2 additional years to establish the short-term dynamics of the river at these locations. Long-term trends will then be documented by re-surveying all 4 reaches on a rotational basis at 5- to 1 O-year intervals. The specific rotation schedule will be identified at a later time based on runoff conditions (surveys should be performed after high runoff years) and, 5 Mussetter Engineering. Inc.