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2.2.2 Wightman to Beaver Creek (Reaches 10, 9, and 8) <br />Below ~Xlightman Fork, the Alamosa River begins to meander within the confines of a 100-foot wide <br />valley. The channel sinuosity of this reach is 1.3, and the stream has an average slope of 0.9%. Burnt <br />Creek is a major tributary that enters this reach. The USGS quadrangle shows a 3,000-foot by 4,000- <br />foot alluvial fan where Burnt Creek enters the Alamosa River. The large fan indicates a high sediment <br />load carried by Burnt Creek, as shown in Figure 2-8. The alluvial fan may also restrict the extent of <br />Alamosa River meandering in this area. <br />s <br />~~ <br />q. <br />_ ~ '. <br />7 ~ ~ ~ <br />'y~ <br />~~RE ~*~ 1. ..`,. ~~ ~- : ~~~~ ~ ~" ~ ~ s + ~ ~ eat r~ ~ ~ ` ~ s ~ iti ,,, ~~w~ sa a,~k"~-., ~~ <br />~~ ~ ti- ~~ ~ ~ ~ ~ ~~ ~ ~ u ~ <br />'~Y. <br />~~ ~ ' ~ , ® ! ~+ ~ •:~~ _ # +~ ~.~i ~1 err a~~ ~~rr _ ~~ ° . ~ ~~ I , ~ :, ' ~- ~~ ~ <br />o <br />i~ ~ ~_ <br />' ~ ~ ~ Dui , ~ _ `~ !'~ I .: ~ ~o ~ ~"~~ '~ . <br />,~ <br />.. a I. ~°~ aq'`~"` , e <br />R~ ~~ ~t ~€~ '~ ~ ~}.~ a ass ~. ~~s~P 5~,~ ~' _ ~~. r~a~'=~®~' .,~.^~ <br />~,y ' - , <br />- •, <br />2.2.3 Beaver Creek to French Creek (Reach 7) <br />This reach of the Alamosa River is very straight and confined by steep valley walls. The USGS <br />quadrangle contours indicate a large landslide coming from the southern side of the valley. The apparent <br />landslide is confining the channel and has created a steepened channel slope. The channel sinuosity is <br />1.0 and the average slope is 1.7%, which is more than twice as steep as the upstream and downstream <br />channels. <br />2.2.4 French Creek to Terrace Reservoir (Reach 6) <br />This reach is similar to the `Xlightman Fork to Beaver Creek reach. The river meanders within a 100- <br />footwide valley. The channel sinuosity of this reach is 1.3, and the stream has an average slope of 0.8%. <br />Sediment begins to drop out as the channel enters the reservoir resulting in local channel aggradation. <br />~1hen Terrace Reservoir was drained in 2003, the channel re-entrenchened into deposited sediments as <br />the backwater condition was removed, as shown in Figure 2-9. ~Xlhen the reservoir is full this reach will <br />once again aggrade as backwater condition flows allow sediment to drop out. <br />Alamosa River Watershed Restoration Master Plan and Environmental Assessment Page 2-13 <br />Figure 2-8. Photo of Burnt Creelc and Sediment Load <br />