EGU22-6262, updated on 30 Sep 2024
https://doi.org/10.5194/egusphere-egu22-6262
EGU General Assembly 2022
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Modelling of changes in hydrological balance in Gambia river basin using two lumped models

Doudou Ba1,2, Petr Máca2, Jakub Langhammer1, and Ansoumana Bodian3
Doudou Ba et al.
  • 1Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague, Albertov 6, Praha 2 128 43, Prague, Czech Republic
  • 2Department of Water Resources and Environmental Modeling, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamycka 1176, Suchdol, 165 21 Prague 6, Czech Republic
  • 3Laboratoire Leïdi ”Dynamique des Territoires et Développement”, Université Gaston Berger (UGB), Saint Louis, Sénégal

This study investigated the calibration performance of hydrological models applying a series of split-sample to crash-test potential combinations of calibration-validation periods under drought type (dry/wet) using lumped models: BILAN and GR2M. A sub-period focused on the drought was systematically selected for model calibration based on a particular climate characteristic (precipitation, temperature, runoff) and a 7-year moving window. This approach gives perception into calibrated parameters transferability overtime under similar or different climate conditions (drought). 

Both lumped models yielded similar results over a set of 6 catchments in a main West African river basin located in Senegal: the Gambia river basin. The Kling-Glupta Efficiency (KGE) was the objective function to assess models’ efficiency. A dependency was found between the model performance and the extent of input data. 

Results have shown that the calibration performance decreases within an extending simulation period width. A focus on the impact of drought type on calibration performance revealed models simulating better dry than wet years. The analysis on how model performance would be affected when calibrated in a climate condition different to the validation (e.g. calibrated in dry(wet) and validated into wet (dry) revealed that calibration over a wetter or dryer condition than the validation and vice-versa may lead to an over(under)estimation of the simulated runoff. 

The results also indicate a general performance loss due to the transfer of calibrated parameters to independent validation periods of −5 to −25%, on average. The shift of model parameters in time (validation) may generate a significant level of errors. The outcome of this study may lead to a master of the uncertainty associated with one hydrological model and a better assessment of runoff in a real-world application.

Keywords: Gambia river basin; calibration; crash test; rainfall-runoff model; BILAN; GR2M; lumped hydrological models;  

How to cite: Ba, D., Máca, P., Langhammer, J., and Bodian, A.: Modelling of changes in hydrological balance in Gambia river basin using two lumped models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6262, https://doi.org/10.5194/egusphere-egu22-6262, 2022.

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