Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 21, 4021-4036, 2017
https://doi.org/10.5194/hess-21-4021-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
10 Aug 2017
Residual uncertainty estimation using instance-based learning with applications to hydrologic forecasting
Omar Wani1,2,a,b, Joost V. L. Beckers2, Albrecht H. Weerts2,3, and Dimitri P. Solomatine1,4,5 1IHE Delft Institute for Water Education, Delft, the Netherlands
2Deltares, Delft, the Netherlands
3Hydrology and Quantitative Water Management Group, Department of Environmental Sciences, Wageningen University, Wageningen, the Netherlands
4Water Resources Section, Delft University of Technology, Delft, the Netherlands
5Water Problems Institute of RAS, Moscow, Russia
acurrently at: Institute of Environmental Engineering, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
bcurrently at: Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
Abstract. A non-parametric method is applied to quantify residual uncertainty in hydrologic streamflow forecasting. This method acts as a post-processor on deterministic model forecasts and generates a residual uncertainty distribution. Based on instance-based learning, it uses a k nearest-neighbour search for similar historical hydrometeorological conditions to determine uncertainty intervals from a set of historical errors, i.e. discrepancies between past forecast and observation. The performance of this method is assessed using test cases of hydrologic forecasting in two UK rivers: the Severn and Brue. Forecasts in retrospect were made and their uncertainties were estimated using kNN resampling and two alternative uncertainty estimators: quantile regression (QR) and uncertainty estimation based on local errors and clustering (UNEEC). Results show that kNN uncertainty estimation produces accurate and narrow uncertainty intervals with good probability coverage. Analysis also shows that the performance of this technique depends on the choice of search space. Nevertheless, the accuracy and reliability of uncertainty intervals generated using kNN resampling are at least comparable to those produced by QR and UNEEC. It is concluded that kNN uncertainty estimation is an interesting alternative to other post-processors, like QR and UNEEC, for estimating forecast uncertainty. Apart from its concept being simple and well understood, an advantage of this method is that it is relatively easy to implement.

Citation: Wani, O., Beckers, J. V. L., Weerts, A. H., and Solomatine, D. P.: Residual uncertainty estimation using instance-based learning with applications to hydrologic forecasting, Hydrol. Earth Syst. Sci., 21, 4021-4036, https://doi.org/10.5194/hess-21-4021-2017, 2017.
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Short summary
We generate uncertainty intervals for hydrologic model predictions using a simple instance-based learning scheme. Errors made by the model in some specific hydrometeorological conditions in the past are used to predict the probability distribution of its errors during forecasting. We test it for two different case studies in England. We find that this technique, even though conceptually simple and easy to implement, performs as well as some other sophisticated uncertainty estimation methods.
We generate uncertainty intervals for hydrologic model predictions using a simple instance-based...
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