Monitoring baseline suspended sediment in forested basins: the effects of sampling on suspended sediment rating curves |
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Authors: | ROBERT B THOMAS |
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Institution: | Pacific Southwest Forest and Range Experiment Station, Forest Service, US Department of Agriculture , 1700 Bayview Street, Arcata , California , 95521 , USA |
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Abstract: | Abstract Rating curves are widely used for directly assessing changes in the suspended sediment delivery process and indirectly for estimating total yields. Four sampling methods were simulated over a 31-day record of suspended sediment from the North Fork of the Mad River near Korbel, California. The position and size of the four groups of plotted slope/intercept pairs indicated differences in bias and variance among the methods. Estimates of total yield for the 31-day period and for storms of three sizes were also biased according to sampling method. A standard bias-correcting technique improved yield estimates, but did not remove sampling bias uniformly. Methods of data collection have a large and systematic effect on the estimation of rating-curve parameters and on estimates of suspended sediment yield. Differences attributed to land management may, in fact, result from changes in sampling methods. |
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