Jarbidge River General Information The headwaters of the Jarbidge River are in northeast Nevada on the Humbolt National Forest. The river flows northward into Idaho and confluences with the Bruneau River. The study area is about a 5,600 ft length of river at the U. S. Geological Survey gaging station (13162225), which is located about 1 mi. downstream of Jarbidge, Nevada. The gage site is at an elevation of about 6,050 ft. The drainage area upstream of the gaging station is 30.6 mi2 and the geology of the watershed is predominantly volcanic extrusive (rhyolite). This U.S. Geological Survey gage was installed in April of 1998. Streamflow records are available from April 22, 1998 to present (Water Year 2012). Sediment transport measurements are available for water years 1998, 1999, 2000 and 2002. Additional information collected at the site includes a survey of a stream reach and pebble counts of the surface bed material. Figures 1 and 2 show photographs of the surveyed reach. Figure 1. Jarbidge River looking downstream near the middle of the surveyed reach. Figure 2. Jarbidge River looking downstream at the lower portion of the surveyed reach. Streamflow records are available beginning on April 22, 1998. As of December 2012 the gage was still in operation. The average annual streamflow (Qa) for the period of record is 35.4 ft3/s (15.7 in). During the period of record, daily mean discharges ranged from 1.0 ft3/s to 633 ft3/s. The highest instantaneous discharge recorded was 1230 ft3/s on May 16, 2005. Page |2 Channel Profile and Cross-Section The surveyed river segment is about a 580 ft reach beginning about 0.6 miles downstream of the USGS gage. Figure 3 shows the longitudinal profile for the channel bed in the center of the channel, the water surface elevations along each bank at the time of the survey and bankfull flow elevations (floodplains). The average gradient for the surveyed reach is 0.0160 ft/ft. Cross-sections of the channel were surveyed at three locations. Figure 4 shows the channel cross-section (XS26) near the middle of the surveyed reach. 98 Water Surface Elevation Right Bank 96 Jarbidge River Center of Channel Bed Elevation Water Surface Elevation Left Bank 94 Bankfull Elevation Right Side Bankfull Elevation Left Side 92 90 XS25 Elevation, ft XS26 88 XS27 USFS Gage 86 84 -300 -200 -100 0 100 200 300 400 Distance, ft Figure 3. Longitudinal profile of the surveyed reach of the Jarbidge River. 100 99 Jarbidge River 98 Cross-Section 26 97 96 95 Elevation, ft 94 Q 93 92 Q - water surface at time of survey 91 -20 0 20 40 60 80 100 120 140 Distance, ft Figure 4. Cross-section 26 of the Jarbidge River. Page |3 Channel Geometry Station geometry relationships (Figure 5) are shown for two sediment transport measurement areas. In 1998 most sediment transport measurements were made 100 to 150 ft upstream of the gage. In subsequent years, most measurements were made 10 to 50 ft downstream of the USGS gage. During high streamflows, sediment transport is measured from the bridge, about 10 to 20 ft downstream of the gage. Information from stream discharge measurements for 1998 through 2002, that spanned the range of discharges during which sediment transport was measured, were used to develop the power relationships. Over the range of discharges when sediment transport was measured (49.2 to 420 ft3/s), estimated stream width, estimated average depth and estimated average velocity vary from 28.8 to 37.5 ft, 0.77 to 1.80 ft, and 2.21 to 6.21 ft/s, respectively, at the upstream site and from 28.9 to 47.2 ft, 0.77 to 1.47 ft, and 2.21 to 6.05 ft/s, respectively, at the downstream site. 100 10 Jarbidge River Width 0.122 Width y = 17.933x 0.228 2 y = 11.901x R = 0.51 2 10 R = 0.69 Average Velocity y = 0.356x0.469 R2 = 0.94 Average Velocity y = 0.3399x0.481 R2 = 0.91 Width and Depth, ft 1 Average Depth Average Velocity, ft/s y = 0.2361x0.303 Average Depth R2 = 0.94 y = 0.1645x0.396 R2 = 0.89 Upstream Site Downstream Site 0.1 1 10 100 1000 3 Discharge,Discharge ft ft3/s /s Figure 5. Width, average depth, and average velocity versus stream discharge for the two sediment transport measurement sites on the Jarbidge River. Page |4 Channel Material A surface pebble count was made in the surveyed reach at cross-section 26 in October 1998. Additional surface pebble counts were made along three transects in October 2000 in a 200 ft. reach, beginning about 200 ft. upstream of the USGS gage. The average D50 and D90 for the surface material were 95 mm and 223 mm, respectively, in 1998 and 89 mm and 209 mm, in 2000 (Figure 6). About 5% (2000) of the surface material was sand (2 mm) size or smaller. 100 Jarbidge River 90 80 70 60 50 Percent Finer 40 30 Downstream Transect Upstream Transect Middle Transect 20 10 Surface 2000 Surface 1998 0 1 10 100 1000 Particle Size, mm Figure 6. Particle size distribution for surface material collected in the Jarbidge River. Page |5 Sediment Transport Sediment transport measurements were made in 1998, 1999, 2000 and 2002. The sediment transport data include 56 measurements of bedload transport and 28 measurements of suspended sediment. Sediment transport measurements spanned a 3 3 range of stream discharges from 49.2 ft /s (1.12Qa) to 420 ft /s (9.55Qa). Bedload transport ranged from 0.0132 to 39.6 t/d and suspended sediment transport ranged from 0.373 to 76.7 t/d. Over the range of measured discharges, suspended transport accounts for the majority of the material in transport (Figure 7). At the lowest measure discharges predicted suspended transport is about four times that of bedload and at the highest measured discharge about 1.3 times. 100 Jarbidge River 10 1 Suspended y = 6E-06x2.661 R2 = 0.84 Total Bedload y = 2E-07x3.177 2 Sediment Transport, tons/day R = 0.59 0.1 Q a Suspended Total Bedload 0.01 10 100 1000 Discharge, ft3/s Figure 7. Bedload and suspended load transport rate versus discharge. (The bias correction factors for bedload and suspended load transport are 1.925 and 1.168, respectively.) Page |6 The bedload transport rates by size class (Figure 8) shows that the larger rates are associated with material in the 0.5 to 2mm diameter size class. Only 13 samples contained material >32mm diameter and associated discharges were greater than 126 ft3/s. 100 Jarbidge River 10 <0.5mm y = 5E-08x2.932 R2 = 0.64 1 0.5-2mm y = 3E-07x2.93 R2 = 0.60 0.1 2-8mm 3.211 Bedload Rate, tons/day y = 4E-08x R2 = 0.56 <0.5mm 0.01 0.5-2mm 8-32mm 2-8mm y = 3E-07x2.710 8-32mm R2 = 0.33 Qa >32mm 0.001 10 100 1000 Discharge, ft3/s Figure 8. Bedload transport rate versus discharge for selected size classes. Page |7 The size of the largest particle size class in the bedload sample typically increased with discharge (Figure 9). The largest particle size class in a bedload sample was 32 to 3 64 mm at discharges of 126 ft /s and larger. The D50 exhibits a weak relationship with discharge. The D50 for the majority of the samples was <2 mm. The largest D50 was 35.4 mm associated with a sampling discharge of 126 ft3/s. The information on the largest particle size class in the bedload sample suggests that discharges larger than the sampled discharges would be needed to transport the median diameter particles on the channel surface. 1000 Jarbidge River Median Size Lower end of largest size class D50 for the three 100 surface pebble counts in 2000 10 Bedload Size, mm R2 = 0.46 1 R2 = 0.06 Qa 0.1 10 100 1000 Discharge, ft3/s Figure 9. Lower end of the largest size class in the bedload sample and median size of the sample versus stream discharge for the Jarbidge River. Page |8 .