Present and potential sediment yields in the Yampa River Basin, Colorado and Wyoming

Abstract

Final 14. Supplementary Notes16. Abstracts Average annual suspended-and total -sediment loads in streamflow were determined by the flow-duration sediment-transport-curve method at 18 sites in the Yampa River basin, Colorado and Wyoming. These computations indicate that about 2.0 million tons (1.8 million metric tons) of sediment are carried by the Yampa River at Deerlodge Park during an average year. Significant areal differences in the sediment yield from various parts of the basin also were determined. The lower Little Snake River subbasin contributes about 60 percent of the total basin sediment yield, although it represents less than 35 percent of the area and supplies less than 3 percent of the streamflow. In contrast, the upland (eastern) one-third of the basin contributes only about 1^ percent of the sediment yield but 76 percent of the streamflow.Projected economic development of the basin, especially surface mining of coal, will impact the physical environment. Depending upon the amount and location of land disturbed, an estimated 10,000 to 30,000 tons per year (9,000 to 27,000 metric tons per of aHHit'innal l rppnt' \/ji 1 1 hp mnt r i hiifprl fri fhp main c;fp.m Yampa Rivp.r. Key ABSTRACTAverage annual suspended-and total-sediment loads in streamflow were determined by the flow-duration sediment-transport-curve method at 18 sites in the Yampa River basin, Colorado and Wyoming. These computations indicate that about 2.0 million tons (1.8 million metric tons) of sediment are carried by the Yampa River at Deerlodge Park during an average year. Significant areal differences in the sediment yield from various parts of the basin also were determined.The lower Little Snake River subbasin contributes about 60 percent of the total basin sediment yield, although it represents less than 35 percent of the area and supplies less than 3 percent of the streamflow. In contrast, the upland (eastern) one-third of the basin contributes only about 14 percent of the sediment yield but 76 percent of the streamflow.

A Sediment Budget for a Sand Bed River Partitioned by Sand Fractions

“…The study area begins 6.4 km downstream from Cross Mountain, where the Little Snake River joins the Yampa River, and the study area extends to the downstream end of Deerlodge Park (Figure 1). At their confluence, the watersheds of the Little Snake River and upper Yampa River are approximately the same size, but approximately 75% of the total flow in Deerlodge Park comes from the upper Yampa River (Andrews, 1978;Topping et al, 2018). Most of the streamflow of the Little Snake River also arises in mountainous headwaters, but this tributary primarily flows through erodible badlands composed of fluvial and lacustrine sediments that are a significant source for fine sediment , as discussed below.…”

“…Although the upper Yampa River contributes most of the streamflow to the study area, only ∼30% of the fine sediment delivered to the study area originates in the upper Yampa River watershed (Andrews, 1978;Topping et al, 2018). Most sediment originates from tributaries to the Little Snake River that drain badlands primarily in the Sand Creek, Muddy Creek, and Sand Wash watersheds (Figure 1a).…”