Measuring Stream Flow and Sediment Transport to Evaluate the Cub River Basin, Idaho
Location
ECC 216
Event Website
http://water.usu.edu/
Start Date
4-5-2007 6:20 PM
End Date
4-5-2007 6:25 PM
Description
The goal of this study is to examine the relations among stream flow diversions, inchannel processes, and the geomorphic framework of river basins. An essential component of this research program is a spatially distributed characterization of streamflow and sediment flux in a channel network affected by multiple diversions and tributary junctions. These data indicate that operation of diversions during the snowmelt runoff season affects the timing and spatial distribution of water and sediment flux. We measured stream flow and sediment transport and developed a geomorphic characterization of the study area. The study area extends from the confluence of Carter Creek to the mouth of the Cub River canyon, near Franklin, Idaho. It is 17 km long and drains approximately of 155 km2. Stream gradient varies from 0.001 to 0.033 and the average peak flow is 17 m3/s. Within the study area two major diversion structures are operated from May through mid-October for irrigation. A third diversion is operated nearly year-round for reservoir filling. We divided the study area into four segments, separated by the three diversions and established study sites in each segment. We measured streamflow at the first three sites and developed stage-discharge relations. We used an acoustic stage-measurement device at one site, which allowed us to construct a continuous record of stage and discharge for most of the runoff season at that location. We also obtained daily measurements of flow for each of the three diversions. We made periodic measurements of flow in the Upper and Lower Diversion to compare these records. We collected 212 bedload measurements during the 2006 runoff season in the Cub River and the diversion canals. Each of the measurements represents a set of three to six individual samples. Measurements were taken with bedload traps (0.3 m x 0.2 m nozzle) and hand-held Elwha sampler (0.2 m x 0.1 m nozzle). Bedload traps were mounted to the bed of the river for 60 minutes. Hand-held measurements were taken for 3 or 5 minutes depending on the flow. At each of the sites we collected at least 20 measurements with bedload traps and 10 measurements with hand-held sampler. We collected additional hand-held samples from nearby sites at road bridges during the peak flows. The measurements indicate a longitudinal variation in bedload similar to the longitudinal variation in discharge. The highest flow and highest sediment transport occurred in downstream reaches that were affected by tributaries earlier in the season, while natural snowmelt resulted in the greatest flow and sediment transport in the upper watershed later in the season. The grain size distribution of the bed load was much finer than the bed surface and similar or finer to that of depositional bars. The bed D50 decreases downstream, but the D50 of the gravel bars is similar throughout the study area. Thus, during a year of average peak runoff, depositional bars appeared to be fully mobilized while the bed was only partially mobilized.
Measuring Stream Flow and Sediment Transport to Evaluate the Cub River Basin, Idaho
ECC 216
The goal of this study is to examine the relations among stream flow diversions, inchannel processes, and the geomorphic framework of river basins. An essential component of this research program is a spatially distributed characterization of streamflow and sediment flux in a channel network affected by multiple diversions and tributary junctions. These data indicate that operation of diversions during the snowmelt runoff season affects the timing and spatial distribution of water and sediment flux. We measured stream flow and sediment transport and developed a geomorphic characterization of the study area. The study area extends from the confluence of Carter Creek to the mouth of the Cub River canyon, near Franklin, Idaho. It is 17 km long and drains approximately of 155 km2. Stream gradient varies from 0.001 to 0.033 and the average peak flow is 17 m3/s. Within the study area two major diversion structures are operated from May through mid-October for irrigation. A third diversion is operated nearly year-round for reservoir filling. We divided the study area into four segments, separated by the three diversions and established study sites in each segment. We measured streamflow at the first three sites and developed stage-discharge relations. We used an acoustic stage-measurement device at one site, which allowed us to construct a continuous record of stage and discharge for most of the runoff season at that location. We also obtained daily measurements of flow for each of the three diversions. We made periodic measurements of flow in the Upper and Lower Diversion to compare these records. We collected 212 bedload measurements during the 2006 runoff season in the Cub River and the diversion canals. Each of the measurements represents a set of three to six individual samples. Measurements were taken with bedload traps (0.3 m x 0.2 m nozzle) and hand-held Elwha sampler (0.2 m x 0.1 m nozzle). Bedload traps were mounted to the bed of the river for 60 minutes. Hand-held measurements were taken for 3 or 5 minutes depending on the flow. At each of the sites we collected at least 20 measurements with bedload traps and 10 measurements with hand-held sampler. We collected additional hand-held samples from nearby sites at road bridges during the peak flows. The measurements indicate a longitudinal variation in bedload similar to the longitudinal variation in discharge. The highest flow and highest sediment transport occurred in downstream reaches that were affected by tributaries earlier in the season, while natural snowmelt resulted in the greatest flow and sediment transport in the upper watershed later in the season. The grain size distribution of the bed load was much finer than the bed surface and similar or finer to that of depositional bars. The bed D50 decreases downstream, but the D50 of the gravel bars is similar throughout the study area. Thus, during a year of average peak runoff, depositional bars appeared to be fully mobilized while the bed was only partially mobilized.
https://digitalcommons.usu.edu/runoff/2007/AllPosters/9