Winner of the Henri Milon Thesis Award 2022 in Hydrology from the SHF

https://www.shf-hydro.org/prix/prix-henri-milon-hydrologie/

Development of an iterative procedure for detecting rating curve shifts in the relationship between stage and discharge at a hydrometric station, with three components:
1/ Method for segmenting residuals between gauging points and a reference curve;
2/ Analysis of recession curves from the limnograph;
3/ Use of an indicator for cumulative sediment transport.

Application to the Ardèche station at Meyras, both retrospectively and in real time.

Abstract

River discharge time series are established using "rating curves", which are models with stage as input and discharge as output. Unfortunately, many hydrometric stations have an unstable stage-discharge relation, particularly because of the change in the river bed during floods. These "rating shifts" pose a problem both for the establishment of long-term hydrological series (retrospective analysis) and for the delivery of real-time data, for example for flood forecasting, with quantified and reliable uncertainties. The existing methods for updating the rating curve are based on a statistical analysis of past calibration data (the gaugings) or on empirical rules. This thesis aims at developing some original methods for the automatic detection of rating shifts and the estimation of their magnitude in both retrospective and real time: a method of segmentation of the residuals between the gaugings and a base rating curve, an analysis of the stage recessions and a method for detecting potential shifts from an indicator available in real time (e.g. cumulative sediment transport). The probabilistic approach allows on the one hand to take into account the uncertainty of the information on the shift and on the other hand to quantify the uncertainties of the calculated streamflow. The combination of the three methods has been applied to the Ardèche at Meyras, France, which shows net shifts after each major flood. Good detection and estimation of the rating shift has been observed retrospectively and in real time. The method is generic and, after further validation, operationally applicable to other sites.

Funding:

50 % CNR,35 % EDF, 15 % SCHAPI

Publications and communications

• Darienzo, M., Renard, B., Le Coz, J., Lang, M. (2018). Détection et estimation des détarages en rétrospectif et en temps réel. Journées de l’Hydrométrie SCHAPI 8-9 Novembre 2018, Toulouse. Présentation orale.
• Darienzo, M., Renard, B., Le Coz, J., Lang, M. (2018). Real-time Bayesian estimation of stage-discharge rating curves during floods. American Geophysical Union Fall Meeting 2018 14/12/2018-14/12/2018, Washington DC, USA. 1 p (poster)
• Mansanarez, V., Renard, B., Le Coz, J., Lang, M., & Darienzo, M. (2019). Shift happens! Adjusting stage-discharge rating curves to morphological changes at known times. Water Resources Research, 55. https://doi.org/10.1029/2018WR023389

Cite the thesis

Matteo Darienzo. Detection and estimation of stage-discharge rating shifts for retrospective and real-time streamflow quantification. Hydrology. Université Grenoble Alpes [2020-..], 2021. English. ⟨NNT : 2021GRALU006⟩. ⟨tel-03211343⟩

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