Changes in Stream Channel Morphology Caused by Replacing Road-Stream Crossings on Timber Harvesting Plans in Northwestern California

Abstract

Past studies have shown that roads used for timber management and recreation are major sources of sedimentation in many streams throughout the Pacific Northwestern United States. Stream crossings are portals for the entry of sediment derived from road surface erosion. They are also prone to catastrophic failure during stressing weather events if they are undersized or otherwise deficient in design or construction. In recent years, public and private landowners have replaced or removed numerous deficient crossings in forested watersheds throughout California and elsewhere in the West. The benefits of replacing these crossings include eliminating both chronic and episodic inputs of sediment to streams. When old crossings are replaced with new, properly designed and installed crossings, there is a potential for construction-related erosion. This research examined the postconstruction erosion associated with the replacement of 30 stream crossings in coastal California. Channel surveys were conducted immediately after construction and after the passage of one winter rainy season. The results indicated very little erosion on most sites; 11 experienced no erosion at all. On those sites where erosion did occur, the amounts did not exceed 10 cubic yards. A few sites experienced aggradation or erosion unrelated to upgrading but due to upstream landslides. This research shows upgraded stream crossings on commercial timberland may contribute little sediment to streams after construction under moderate weather conditions if adequate erosion control measures are implemented.

Operational Forest Stream Crossings Effects on Water Quality in the Virginia Piedmont

“…Permanent haul roads are also more expensive to cover with stone. However, Harris et al (2008) found that aggressive use of a combination of armor, silt fences, water control, and erosion vegetation practically eliminated water quality concerns associated with 30 stream crossings on public lands in California.…”

“…tream crossings are often considered to be the forest road segment with the greatest potential to introduce sediment into streams (Rothwell 1983, Swift 1985, Milauskas 1988, Aust and Blinn 2004, Harris et al 2008. Typical stream crossings found on current timber harvest operations include fords, culverts, and bridges (Brinker 1997, Blinn et al 1998, Aust et al 2003.…”

“…This study was designed to investigate relatively simple measures of water quality and indices of potential erosion on multiple replications of four forest stream crossing types. This study incorporated the findings of Taylor et al (1999aTaylor et al ( , 1999b and Harris et al (2008) and evaluated stream crossing approaches and phases of use with the overall goal of identifying potential improvements for stream crossing best management practices (BMP). As suggested by Loftis et al (2001), upstream and downstream data were collected during all phases, which provided a control for comparison.…”

Improving drainage conditions of forest roads using the GIS and forest road simulator

“…Also, on some horizontal curves, the superelevation is in opposite position to the ditch (Figure 4D). Harris et al (2008) introduced a longitudinal profile as one of the most important factors in decision-making. Using the analysis of microtopography (Figure 3) it can be obtained that we can use waterfronts No.…”

Best Management Practices Influence Modeled Erosion Rates at Forest Haul Road Stream Crossings in Virginia

“…Harris et al. () found that structures replaced in California on sites with extensive erosion control methods recovered significantly within one rainy season.…”