Two US Forest Service draft monitoring protocols are used to assess the effectiveness of design channels at road-stream crossings by comparing their physical channel dimensions to those in the natural channel. Level II physical monitoring is a time intensive, quantitative and statistically based procedure for assessing effectiveness at selected sites. Level I physical monitoring is a less detailed, rapid procedure limited to a few simple measurements and observations for assessing effectiveness at a large number of sites. Study objectives were to: 1) test and refine the field methods for collecting data by the levels I and II physical monitoring protocols; 2) find a meaningful way to combine the data collected by levels I and II into separate effectiveness evaluations by each protocol; and, 3) evaluate whether the level I protocol can be used as a proxy for the level II protocol. Where the two protocols systematically differ, field data help distinguish why.
Study results for all objectives (combined) include: improved field methodologies, recommendations for further development, and separate summary rubrics for the levels I and II monitoring protocols. The recommendations are of three categories; channel metrics/data collection, methods of scoring each metric, and sample sizes. Some of most significant of those recommendations are described within the following paragraphs.
Data collection methods might be improved to save time, increase the accuracy of protocol evaluations, and facilitate agreement between the levels I and II protocol evaluation results. The techniques by which the level I bankfull stage and coarse fraction of the gradation metrics are collected should incorporate level II methods. Instructions for collecting level II coarse fraction of the gradation data should specify measuring all particles within the channel, including particles much larger than the sampling frame. The level I method by which the representative reach is selected should incorporate a basic longitudinal profile survey in which only the most prominent grade controls separating slope segments are captured. Decreasing the allowable gradient difference between the level II design channel and representative reach might also improve accuracy. The method by which the levels I and II protocols compare channel units (or channel unit sequences) between the design and representative reach should be equivalent, as should the rules by which slope segments and channel units are defined. Finally, the channel metrics of low flow width and bed irregularity are inconsistent with the objectives of physical effectiveness monitoring, in that they are aspects of habitat, rather than strong controls on channel form. I suggest they be eliminated from the levels I and II protocols.
The level II summary rubric scores most metrics statistically by a Wilcoxon Rank-Sum test of medians. For most metrics, the Wilcoxon Rank-Sum test appears to be a reasonable way to compare representative reach and design zone data. For the metrics of bed and bank irregularity, however, a test of distributions (e.g., Kolmogorov-Smirnov) is recommended instead. The coarse fraction of the gradation metric would be more fairly assessed if the modes of the particle size (in phi units) were compared instead of the medians. Doing so would allow the design and representative reach gradients to be slightly different (as does the criteria for selecting a representative reach) without penalizing the metric score.
The levels I and II summary rubric tools created were used to evaluate twelve AOP road-stream crossing designs. The performance of the levels I and II summary rubrics were then assessed by the evaluation results at those twelve sites. Levels I and II generally seemed to provide effectiveness evaluations which agreed with site observations, data, and photographs. Further, the summary rubrics facilitated concurrent evaluation of the many channel dimensions which together affect the hydraulic conditions experienced by aquatic organisms. In addition, the simple utility of the levels I and II summary rubric tools should encourage effectiveness monitoring and help restoration practitioners learn from their mistakes, ultimately improving aquatic organism passage design methods and results. (Abstract shortened by UMI.)
|Commitee:||Bledsoe, Brian, Cenderelli, Daniel, Rathburn, Sara|
|School:||Colorado State University|
|School Location:||United States -- Colorado|
|Source:||MAI 53/02M(E), Masters Abstracts International|
|Subjects:||Geomorphology, Natural Resource Management, Environmental engineering|
|Keywords:||Aquatic organism passage, Effectiveness, Monitoring, Protocol, Road-stream crossings, Stream simulation|
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