An approach for appraising the accuracy of suspended-sediment data

Procedures are presented for appraising the accuracy of suspended-sediment data. Types of errors involved are sampling error, spatial error, temporal error, and sediment-discharge error. The standard error of estimate is used to represent errors. Suspended-sediment data for 17 U.S. Geological Survey gaging stations in Arizona, California, Nebraska, New Mexico, Pennsylvania, and Washington are used in applications of the procedures. For the study sites, the magnitudes of the different types of error apparently vary directly with percentage of sediment-water mixture that is sand; when the percentage sand is relatively high, magnitudes of the different types of error have a relatively wide range. For seven sites of the Sacramento River , Calif., and its tributaries, the standard sampling error apparently can range from 2.5 percent when percentage sand is relatively low to 20 percent when percentage sand is relatively high. For 16 sites in Arizona, California, Nebraska, New Mexico, and Pennsylvania, the coefficient of variation for concentrations of suspended sediment across streams apparently can range from 2.5 percent (low percentage sand) to 70 percent (high percentage sand). (USGS)