the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Drainage assessment of irrigation districts: on the precision and accuracy of four parsimonious models
Pierre Laluet
Luis Olivera-Guerra
Víctor Altés
Vincent Rivalland
Alexis Jeantet
Julien Tournebize
Omar Cenobio-Cruz
Anaïs Barella-Ortiz
Pere Quintana-Seguí
Josep M. Villar
Olivier Merlin
Abstract. In semi-arid irrigated environments, the agricultural drainage is at the heart of three agro-environmental issues: it is an indicator of water productivity, it is the main control to prevent soil salinization and waterlogging problems, and it is related to the health of downstream ecosystems. Crop water balance models combined with subsurface models can be used to estimate the drainage quantities and dynamics at various spatial scales. However, the precision (capacity of a model to fit the observed drainage using site-specific calibration) and accuracy (capacity of a model to approximate observed drainage using default input parameters) of such models have not yet been assessed in irrigated areas. To fill the gap, this study evaluates four parsimonious drainage models based on the combination of two surface models (RU and SAMIR) and two subsurface models (Reservoir and SIDRA) with varying complexity levels: RU-Reservoir, RU-SIDRA, SAMIR-Reservoir, and SAMIR-SIDRA. All models were applied over two sub-basins of the Algerri-Balaguer irrigation district, northeastern Spain, that are equipped with surface and subsurface drains driving the drained water to general outlets where the discharge is continuously monitored. Results show that RU-Reservoir is the most precise (average KGE (Q0.5) of 0.87), followed by SAMIR-Reservoir (average KGE (Q0.5) of 0.79). However, SAMIR-Reservoir is the most accurate model for providing rough drainage estimates using the default input parameters provided in the literature.
Pierre Laluet et al.
Status: open (until 07 Jul 2023)
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RC1: 'Comment on egusphere-2023-543', Anonymous Referee #1, 08 May 2023
reply
(1) Table 6: Why are the parameter values different between 2021 and 2022 periods? I guess that 2021 period is regarded as the calibration period and 2022 period is regarded as the validation period. It's weird if you calibrate both two periods.
(2) The four models evaluated herein result from the combination of two water balance models (RU and SAMIR) and two drainage discharge models (Reservoir and SIDRA). I'm confused why you don’t use the same parameter values to describe the same physical process. For example, the values of parameter Sinter (mm) used in the RU-Reservoir and RU-SIDRA are different in Table 6. It feels like a black box model study, if we don't use the same parameter values to describe the same process.
(3) I suggest add more comparison between the results of the two sub-basins AB1 and AB2, as the latter is more than ten times the size of the former.
(4) I agree that the simple model RU-Reservoir presents a better precision in your study. But I still think that in general the more complex the model, the better the simulation result.
(5) I am confused why you simulated the models with the default values. Is it to reduce the work of parameter calibration?
Citation: https://doi.org/10.5194/egusphere-2023-543-RC1
Pierre Laluet et al.
Pierre Laluet et al.
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