Piecewise SALT Sampling for Estimating Suspended Sediment Yields

A probability sampling method called SALT (Selection At List 'Time) has been developed for collecting and summarizing data on delivery of suspended sediment in rivers. It is based on sampling and estimating yield using a suspended-sediment rating curve for high discharges and simple random sampling for low flows. The method gives unbiased estimates of total yield and variance. The technique has been modified by replacing the rating curve with a user-specified average sampling rate function. This function allows easier specification of field sampling parameters for specified conditions and helps avoid the extremes of data collection. It also improves the distribution of samples if the intent is to estimate suspended sediment yield during storms specified after data collection. This form of SALT sampling is called Piecewise SALT sampling. The Author: ROBERT B. THOMAS is a mathematical statistician assigned to the Station's research unit studying the effects of forest management on hillslope processes, fishery resources, and stream environments, and is stationed in Arcata, California. Acknowledgment: I thank the Simpson Timber Company for its cooperation in collecting data at the test site.