The authors need to be commended for pursuing this empirical approach to predict annual streambank erosion. As intended, this study was partially designed to determine if regional relations of observed erosion rates for streams in the Sequoia National Forest using the BEHI and NBS predictors varied from other regions. The results indicated much lower erosion rates for the Sequoia National Forest compared to previous curves (i.e., Colorado, Yellowstone, North Carolina, Arkansas, and NE Kansas). The authors suggest that the soils on the Sequoia NF may be more stable as a possible rational for the low erosion rates; although this is possible, I would like to provide a few other possibilities.One possibility for the low erosion rates can be related to the data collected during years where flows reached only 65% of the bankfull discharge; it appears that at least half of the 137 data points were collected during these flows (Table 3 in Kwan and Swanson). The Colorado and Yellowstone curves were developed under bankfull flow conditions. Furthermore, the Colorado and Yellowstone curves were developed from all bed features and were not limited to riffles as in this study. Erosion rates tend to be much less at riffle locations, and with the lack of near-bank stress data for High/Very High and Extreme ratings (Figure 4 in Kwan and Swanson), the resultant streambank erosion rate curves would tend to be lower.The authors also state that one reason sites were not monitored repeatedly was due to loss of pins; the erosion rates could potentially be higher than reported if 1.0-m bank pins were lost due to erosion and were not included in the dataset. I recommend that all bank study sites be set up with permanent cross-section pins and toe pins to prevent data loss if the erosion pins are lost. Also, if toe pins are buried due to bank failure, the toe pins must be unburied to resurvey the bank or a cross section can be taken if the permanent cross-section pins are still intact.The authors also suggest that the bank-height ratio may be useful to explore as a rapid alternative to the combined variables of the BEHI rating to predict the annual erosion rates. Such a recommendation should be implemented only if that variable was separated and tested against observed data. This may be a good subject for additional research. I recommend that all the BEHI variables be used in the prediction as they represent relations that address a large range of erosional processes responsible for annual streambank erosion rates.Lastly, as additional streambank erosion rate data become available, it would be advantageous to develop a set of curves for respective BEHI and NBS relations for flood, bankfull, and dry-year observed data.
This erratum corrects a typographical error in Table 4: Moderate BEHI and High NBS for Sequoia NF should read 0.02. The corrected table is shown here.
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