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

Alexis Jeantet,Julien Tournebize,Guillaume Thirel,Cédric Chaumont,Lila Collet,Hocine Henine

doi:10.5194/hess-25-5447-2021

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 to represent the variability in pedoclimatic conditions within French metropolitan areas and 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–clay, and clayey). The performance of SIDRA-RU is evaluated by monitoring both the set of KGE′ calibration values and the quality of simulations on each plot with respect to high and low discharges, as well as the annual drained water balance. Next, the temporal robustness of the model is assessed by conducting, on selected plots, the split-sample test capable of satisfying the data requirements. Results show that the SIDRA-RU model accurately simulates 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 replicates the diversity of French drained soil and could be used for its long-term management potential.

Highlights

Subsurface drainage is an agricultural soil management technique that controls soil water content and increases aeration in soils subjected to temporary or permanent water saturation issues into the soil depth (Jamagne, 1968; Baize and Jabiol, 2011)
To the best of our knowledge, in drainage modeling, the models are often evaluated on a short-term database, with just a few years on a few sites, e.g., DRAINMOD (Skaggs et al, 2012), MACRO (Jarvis and Larsbo, 2012), ADAPT (Gowda et al, 2012), and SWAT (Arnold et al, 2012)
Results indicate that the SIDRA-RU model yields satisfactory drainage discharge simulations for most studied sites

Summary

Introduction

Subsurface drainage is an agricultural soil management technique that controls soil water content and increases aeration in soils subjected to temporary or permanent water saturation issues into the soil depth (Jamagne, 1968; Baize and Jabiol, 2011). Drained soils often belong to the hydromorphic soil category and sometimes, in the French context, lie on a shallow and impervious layer that reduces the deep infiltration (Thompson et al, 1997; Lange et al, 2011). In France, all artificially drained soils comprise more than 2.7 million ha of arable soils (RGA – Agreste, 2010), i.e., close to 10 % of all arable land, corresponding to about 20 % for cereal-type field crops. Several techniques exist to drain soils, such as subsurface drainage and open ditch. In France, over 80 % of drainage practices are conducted by introducing perforated pipes lying on the impermeable layer. The drain depth, spacing, slope, and diameter of these pipes constitute the main characteristics of each design; they are constrained by the local study site conditions, such as soil characteristics and climate (Mulqueen, 1998)

Objectives

Methods

Results

Discussion

Conclusion