Water balance in the Dutch river Rhine and rating curve uncertainty

Accurate rating curves are essential for a wide range of river management pur­ poses, particularly as a basis for flood risk management. In our research, we investigate rating curve uncertainties as related to flow measurement errors. We consider the three largest Dutch river Rhine branches (Bovenrijn, Waal and Pannerdensch Kanaal) and the bifurcation point Pan­ nerdense Kop. Comparing the official rating curves for these river channels shows that the water balance is not closing (up to 5% deviation), and this gives a direct indication of the uncertainty in the rating curves. We quantify rating curve uncertainty using Bayesian inference and Markov chain Monte Carlo simulations, as based on homogenous measurement data sets. Next, we show how water balance considerations can influence the uncertainty of rating curves. Finally, we dis­ cuss implications for current flood risk norms in the Netherlands and implications for future hydrometric campaigns.