HR: 1330h
AN: H52A-1152    [PDF]
TI: Statistical Analysis of Streambed Sediment Grain Size Distributions: Implications for Environmental Management and Regulatory Policy
AU: * Rosser, B J
EM: brendar@oe-i.com
AF: O'Connor Environmental Inc., PO Box 794, Healdsburg, Ca 95448
AU: * Rosser, B J
EM: brendar@oe-i.com
AF: Institute of Natural Resources, Massey University, Palmerston North, 5301 New Zealand
AU: O'Connor, M D
EM: matto@oe-i.com
AF: O'Connor Environmental Inc., PO Box 794, Healdsburg, Ca 95448
AB: The status of fish habitat in cold water streams in western North America has, by most accounts, been degraded significantly by sedimentation. In particular, land management activities induce erosion that contributes excess sand-size and finer sediment to stream systems, which is believed to have caused increases in the proportion of fine sediment in spawning gravels. Many watershed studies and regulatory programs have, drawing on previous scientific investigations, set thresholds for fine sediment concentrations in spawning beds. This study examines data from gravel bed streams collected with a McNeil sampler in northern California (typically 25 kg), as well as bulk sediment samples from the Waipaoa River in New Zealand (typically 50 kg). Confidence intervals for various percentiles of the grain size distributions were computed from these data using a two-stage sampling approach. Accuracy and precision of data from these sampling programs were considered in relation to the biological/regulatory thresholds as well as the effort required to obtain, process and analyze grain size distributions. Typically, very large samples are required to obtain data with high precision, suggesting that in many circumstances, it may be difficult to assess whether regulatory thresholds are exceeded.
DE: 1800 HYDROLOGY
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
SC: Hydrology [H]
MN: 2003 Fall Meeting