Field measurements of riverbed scour at bridge piers were pursued during this research. This would provide additional information to determine applicability of an empirical estimating procedure for estimating such scour. Two field sites on the Okanagon River, and one on the Yakima River were established; these were added to five sites already in existence.
Because direct measurement of scour depth during the highest stream flows cannot be made with accuracy, an indirect method of determining scour occurrences was established. In general, clear water scour occurs during high flows, some scour hole refill would occur during flow recession. Otherwise, no refill could exist. Field measurement of clear water scour quality was planned to define the possibility of scour hole refill.
Snow packs in the State of Washington during the winter of 1987-88 were unusually low. Thus, flowrates from snowmelt were insufficiently high to create riverbed scour. Consequently, conclusive evidence about scour at bridge piers didn't materialize.