The aim of this study was to understand the uncertainty of estimating loads for observed herbicides and nutrients during a flood event and provide guidance on estimator selection. A high-resolution grab sampling campaign (258 samples over 100 h) was conducted during a flood event in a tropical waterway in Queensland, Australia. Ten herbicides and three nutrient compounds were detected at elevated concentrations. Each had a unique chemograph with differences in transport processes (e.g. dependence on flow, dilution processes and timing of concentration pulses). Resampling from the data set was used to assess uncertainty. Bias existed at lower sampling efforts but depended on estimator properties as sampling effort increased: the interpolation, ratio and regression estimators became unbiased. Large differences were observed in precision and the importance of sampling effort and estimator selection depended on the relationship between the chemograph and hydrograph. The variety of transport processes observed and the resultant variability in uncertainty suggest that useful load estimates can only be obtained with sufficient samples and appropriate estimator selection. We provide a rationale to show the latter can be guided across sampling periods by selecting an estimator where the sampling regime or the relationship between the chemograph and hydrograph meet its assumptions: interpolation becomes more correct as sampling effort increases and the ratio becomes more correct as the r² correlation between flux and flow increases (e.g. > 0.9); a stratified composite sampling approach, even with random samples, is a promising alternative.

这项研究的目的是了解洪水事件期间估算的除草剂和养分估算负荷的不确定性，并为估算器的选择提供指导。在澳大利亚昆士兰州的热带水道发生洪水事件期间，进行了高分辨率抓取采样活动（在100小时内进行了258个采样）。在升高的浓度下检测到十种除草剂和三种营养化合物。每个都具有独特的化学扫描仪，其传输过程有所不同（例如，对流量，稀释过程和浓度脉冲定时的依赖性）。从数据集重采样用于评估不确定性。偏差在较低的抽样工作量下存在，但随着抽样工作量的增加，依赖于估计量的属性：插值，比率和回归估计量变得无偏。在精度上观察到很大的差异，采样工作量和估计量选择的重要性取决于化学图和水位图之间的关系。观察到的运输过程的多样性以及不确定性的最终可变性表明，只有在有足够的样本和适当的估算器选择的情况下，才能获得有用的荷载估算。我们提供了一个原理，表明可以通过选择一个估计器来指导后者在整个采样周期内进行选择，在该估计器中采样方案或化学图与水文图之间的关系满足其假设：随着采样工作量的增加，插值变得更加正确，随着采样量的增加，比率变得更加正确。 [R 观察到的运输过程的多样性以及不确定性的最终可变性表明，只有在有足够的样本和适当的估算器选择的情况下，才能获得有用的荷载估算。我们提供了一个原理，表明可以通过选择一个估计器来指导后者在整个采样周期内进行选择，在该估计器中采样方案或化学图与水文图之间的关系满足其假设：随着采样工作量的增加，插值变得更加正确，随着采样量的增加，比率变得更加正确。 [R 观察到的运输过程的多样性以及不确定性的最终可变性表明，只有在有足够的样本和适当的估算器选择的情况下，才能获得有用的荷载估算。我们提供了一个原理，表明可以通过选择一个估计器来指导后者在整个采样周期内进行选择，在该估计器中采样方案或化学图与水文图之间的关系满足其假设：随着采样工作量的增加，插值变得更加正确，随着采样量的增加，比率变得更加正确。 [R²通量和流量之间的相关性增加（例如> 0.9）；分层复合采样方法（即使是随机样本）也是一种有前途的替代方法。