Robustness of a parsimonious subsurface drainage model at the French national scale

Abstract

Abstract. Drainage systems are currently implemented on agricultural plots subjected to temporary or permanent waterlogging issues. Drained plots account for 9 % of all arable soils in France. As such, the need for accurate hydrological modeling is crucial, especially in an unstable future context affected by climate change. The aim of this paper is to assess the capacity of the SIDRA-RU hydrological drainage model in representing the variability of pedoclimatic conditions within French metropolitan areas, as well as to demonstrate the utility of this model as a long-term management tool. The model is initially calibrated using the KGE' criterion as an Objective Function (OF) on a large and unique database encompassing 22 plots spread across France and classified according to three main soil textures (silty, silty-clayey and clayey). The performance of SIDRA-RU is evaluated by monitoring the KGE' calibration values, as well as the quality of the simulations of both high and low discharges and the annual drained water balance on each plot. Next, the temporal robustness of the model is assessed by conducting the split-sample test on the selected plots that satisfy the data requirements. Results show that the SIDRA-RU model accurately simulates the drainage discharge, especially on silty soils. The performance on clayey soils is slightly weaker than that on silty soils yet remains acceptable. Similarly, the split-sample test indicates that SIDRA-RU is temporally robust on all three soil textures. Consequently, the SIDRA-RU model closely represents the diversity of French drained soil and could be used for its long-term management.

Land drainage functioning and hydrological impacts in rural catchments: model development and field experiments

“…Kao et al, 1998, Augeard et al, 2005, in particular at the "La Jaillière" experimental site. The field experiment of La Jaillière is located in Maine et Loire [Henine et al, 2022, Jeantet et al, 2021 and was equipped since the early 1990s to monitor the functioning of drainage systems as well as their impacts on water quality. For this purpose, it was equipped to measure both subsurface drainage and surface runoff, since their relative proportions have important consequences on the transport of: (i) solute products such as nitrates, mostly transferred by subsurface flows, and (ii) non-solute products associated with soil particles such as most pesticides, mostly transferred by surface runoff.…”

“…The SIDRA model, initially developed and validated on two specific sites (Arrou and La Jaillière), was subsequently shown to predict drain flow rates and water table elevations on other sites. Its robustness was tested on 23 experimental sites in France with contrasting soil and climatic contexts [Jeantet et al, 2021]. These sites were monitored from 1969 to 2017.…”

“…SIDRA-RU requires few parameters as compared to other drainage models such as MACRO [Jarvis et al, 1997, Larsbo andJarvis, 2003] or DRAINMOD [Skaggs et al, 2012]. To obtain these parameters, two methods were used: regional delineation from calibrated values of the observed discharges on the 23 sites and using the split-sample test on nine of these 23 sites [Jeantet et al, 2021], or directly from on-site measurements through pumping tests such as Guyon's test [Lesaffre, 1990].…”