Measuring Wind-Blown Sediments in the Boise Foothills
Soils on north-facing slopes contain a greater silt fraction than on south-facing slopes in the Dry Creek Experimental Watershed (DCEW) (Smith et al, 2011). The DCEW is a northeast to southwest trending basin northeast of Boise Idaho with cold wet winters and hot dry summers. The lower elevations are dominated by grass and shrubs while the higher elevations support a Douglas-Fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) forest. The accumulation of wind-blown sediments (loess) may be an important source of silt within the watershed; however modern contributions from loess deposition have not been measured. Measurements of modern loess deposition can be used to 1) quantify dust transport in the Boise foothills, 2) investigate the origin of the loess using its chemical signature, and 3) examine variations in loess deposition based on aspect and elevation. In order to answer these questions, a consistent sampling method must be established. We constructed loess samplers using open container glass beads and installed them at several different elevations within the DCEW near existing meteorological stations monitored by Boise State University. Additional samplers will be installed throughout the watershed on north and south aspects at equal elevations and hillslope position to evaluate the significance between aspect orientation and loess deposition.
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