Scholarly record
EVALUATION OF STAGE??DISCHARGE RATING CURVES AND RIVER PROFILES IN THE MARITSA RIVER FLOOD WARNING SYSTEM AND DEVELOPMENT OF RECOMMENDATIONS FOR THEIR REVISION
Abstract
Reliable stage-discharge rating curves are essential for flood forecasting and warning systems because they convert observed water levels into discharge estimates used for forecasting, warning thresholds, and operational decision-making [1]. This study evaluates the consistency of the stage-discharge rating curves and surveyed river cross-sections currently used in the Maritsa River flood warning system and develops recommendations for their revision. Four representative hydrometric stations along the Maritsa River are analysed in downstream order: Pazardzhik, Plovdiv, Dimitrovgrad, and Svilengrad. For each station, available discharge measurements, water-level records and annually surveyed geodetic cross-sections are examined. The existing operational rating curves are compared with revised curves developed in BaRatinAGE software using a Bayesian framework, Markov Chain Monte Carlo simulation, and change-point analysis. Simplified hydraulic configurations are defined for each station on the basis of geodetic cross-sections and hydraulic interpretation of channel geometry. These configurations included hydraulic controls, activation stages, channel geometry parameters, bed slope, and Strickler roughness coefficients. Prior rating curves are derived from these hydraulic assumptions and subsequently updated using measured discharge data, parameter uncertainty, and structural uncertainty models [2, 3]. Posterior rating curves, uncertainty bands, residuals, and parameter-consistency diagnostics are then used to assess the stability of the stage-discharge relationship. Preliminary diagnostics indicate that the proposed workflow can identify periods and hydraulic control ranges where rating-curve uncertainty and parameter inconsistency warrant further hydrometric review. The study also examines whether updated BaRatinAGE analyses can support more frequent operational revision of rating curves when new discharge measurements become available.
Publication details
References5
USGS WaterWatch. Stage-discharge relations. Available at: https://waterwatch.usgs.gov/wwhelps/ratings.html
Le Coz, J., Renard, B., Bonnifait, L., Branger, F., and Le Boursicaud, R. (2014). Combining hydraulic knowledge and uncertain gaugings in the estimation of hydrometric rating curves: A Bayesian approach. Journal of Hydrology, 509, 573-587. DOI: 10.1016/j.jhydrol.2013.11.016
BaRatinAGE documentation. Hydraulic controls. Available at: https://baratin-tools.github.io/en/doc/topics/hydraulic-controls/
WMO. Manual on Flood Forecasting and Warning, WMO-No. 1072. Available at: https://www.preventionweb.net/publication/manual-flood-forecasting-and-warning
Kiang, J.E., Gazoorian, C., McMillan, H., Coxon, G., Le Coz, J., Westerberg, I.K., Belleville, A., Petersen-Øverleir, A., Reitan, T., Freer, J., Renard, B., Mansanarez, V., and Mason, R. (2018/2019). A comparison of methods for streamflow uncertainty estimation. Water Resources Research. DOI: 10.1029/2018WR022708