Accuracy and precision of nitrate load estimation with different sampling frequencies for Illinois agricultural watersheds
Journal
the World Water and Environmental Resources Congress 2001
Journal Volume
111
Date Issued
2004
Author(s)
Abstract
The total mass of nitrate passing a gauging station during a period of study may be estimated based on infrequently monitored nitrate concentration data. To examine the accuracy and precision of these nitrate load estimates, a Monte Carlo sub-sampling study was conducted using six years of daily nitrate concentration and daily average discharge data at one gauging station on a medium, size river in central Illinois draining predominantly agricultural lands. The daily nitrate concentration data set was sub-sampled repetitively to generate multiple sub-samples that might have been drawn if a different sampling frequency was used. Load estimation methods from three broad classes were used to calculate nitrate loads based on the generated sub-samples. It was found that the regression-based estimators are all positively biased when applied for the subject study site. The simple ratio estimator and the flow-weighted average estimator, however, are almost bias free and have an overall performance similar to that of the rating curve estimator.
SDGs
Type
conference paper