“R1‐R4” AND “BOISED” SEDIMENT PREDICTION MODEL TESTS USING FOREST ROADS IN GRANITICS¹

Abstract

Erosion and sedimentation data from research watersheds in the Silver Creek Study Area in central Idaho were used to test the prediction of logging road erosion using the R1-R4 sediment yield model, and sediment delivery using the "BOISED" sediment yield prediction model. Three small watersheds were instrumented and monitored such that erosion from newly constructed roads and sediment delivery to the mouths of the watersheds could be measured for four years following road construction. The errors for annual surface erosion predictions for the two standard road tests ranged from +3 1.2 tihalyr (+15 percent) to -30.3 tfhalyr (-63 percent) with an average of zero tihalyr and a standard deviation of the differences of 18.7 t/halyr. The annual prediction errors for the three watershed scale tests had a greater range from -40.8 t/ha/yr (-70 percent) to +65.3 t/halyr (+38 percent) with a mean of -1.9 tlhalyr and a standard deviation of the differences of 25.2 tiha/yr. Sediment yields predicted by BOISED (watershed scale tests) were consistently greater (average of 2.5 times) than measured sediment yields. Hilislope sediment delivery coefficients in BOISED appear to be overly conservative to account for average site conditions and road locations, and thus over-predict sediment delivery. Mass erosion predictions from BOISED appear to predict volume well (465 tonnes actual versus 710 tonnes predicted, or a 35 percent difference) over 15 to 20 years, however mass wasting is more episodic than the model predicts.(KEY TERMS: sediment model; BOISED; erosion; sediment prediction; test.) JAWRAKetcheson, Megahan, and King

Enhanced sediment delivery in a changing climate in semi-arid mountain basins: Implications for water resource management and aquatic habitat in the northern Rocky Mountains

“…data). Event-based road-surface erosion values are from observed, post-construction erosion (4-year average yield, Ketcheson et al, 1999). within a given study region, climate-driven changes in the supply and transport of bed load material may not be realized to downstream reservoirs for centuries to millennia.…”

Effects of forest road amelioration techniques on soil bulk density, surface runoff, sediment transport, soil moisture and seedling growth

“…www.elsevier.com/locate/foreco Forest Ecology and Management 202 (2004) [313][314][315][316][317][318][319][320][321][322][323] These forest roads are the largest source of sediment in forested systems (Ketcheson et al, 1999;Swift, 1988). Erosion of organic and nutrient rich surface soil and compaction decreases forest productivity (Pritchett and Fisher, 1987) and the transport of sediment to streams and subsequent sedimentation leads to loss of stream habitat and altered steam hydrology (NCASI, 1999a(NCASI, , 1999b.…”

Effects of rubber-tired skidder and farm tractor on physical properties of soil in plantation areas in the north of Iran

“…Mechanized harvesting has the potential not only to increase production but also to reduce labour costs resulting in lower total logging costs. Timber forest harvesting operations in the terrain require the construction of a relatively dense network of forest roads, including skid roads, haul roads and landings (Ketcheson et al 1999).…”