Methods for estimation loads transported by rivers

Abstract. Ten methods for estimating the loads of constituents in a river were tested using data from the River Don in North-East Scotland. By treating loads derived from flow and concentration data collected every 2 days as a truth to be predicted, the ten methods were assessed for use when concentration data are collected fortnightly or monthly by sub-sampling from the original data. Estimates of coefficients of variation, bias and mean squared errors of the methods were compared; no method consistently outperformed all others and different methods were appropriate for different constituents. The widely used interpolation methods can be improved upon substantially by modelling the relationship of concentration with flow or seasonality but only if these relationships are strong enough.