Influence of rock glaciers on stream hydrology, La Sal Mountains, Utah, U.S.A

Despite substantial work on some aspects of rock glacier hydrology, there have been no comparisons between drainage basins containing rock glaciers and those without. This thesis examines summer runoff from two basins in the La Sal Mountains: the non-rock glaciated Wet Fork and rock glaciated Gold Basin. Discharge was indirectly calculated using resident water pressure transducers secured to the bed of the stream to determine water height in each surveyed channel along with the Manning equation to estimate velocity. A flume in Gold Basin measured discharge from a rock glacier occupying approximate 6% of the total basin area. Storm precipitation was recorded using a tipping bucket rain gage. Runoff events were analyzed for volume of stormflow, stormflow duration and peak flow duration. Four events were recorded in Wet Fork (n = 4), five events were recorded in Gold Basin (n = 5), and six events at the Gold Basin flume (n = 6). Wet Fork hydrographs are dominated by baseflow throughout the summer and a small proportion (0.13--0.31%) of precipitation leaves the basin as stormflow during storms. Gold Basin hydrographs are characterized by early season snowmelt with flood peaks associated with summer storms. Runoff from the gaged rock glacier represents 15--30% of total basin runoff, and is inversely related to precipitation and directly related to rainfall intensity. Removal of rock glacier hydrographs from total basin hydrographs indicate that there is increased surface runoff from alpine drainage basins which contain rock glaciers, suggesting rock glaciers act as impervious surfaces. Alpine drainage basins with rock glaciers have greater surface runoff and higher flood peaks than drainage basins that lack rock glaciers.