Hybrid fitting of a hydrosystem model: Long‐term insight into the Beauce aquifer functioning (France)

Abstract

[1] This study aims at analyzing the water budget of the unconfined Beauce aquifer (8000 km 2 ) over a 35 year period, by modeling the hydrological functioning and quantifying exchanged water fluxes inside the system. A distributed process-based model (DPBM) is implemented to model the surface, the unsaturated zone and the aquifer subsystems. Based on an extensive literature review on multiparameter optimization and inverse problem, a pragmatic hybrid fitting method that couples manual and automatic calibration is developed. Three data subsets are used for calibration (10 year), validation (10 year) and test (35 year). The global piezometric head root-mean-square error is around 2.5 m for the three subsets and is rather uniformly spatially distributed over 78 piezometers. The sensitivity of the simulation to the different steps of the calibration process is investigated. The transmissivity field permits the fitting of the low-frequency signal for long-term filtering of the recharge signal, whereas the storage coefficient filters the signal with a higher frequency. For long-term insight into aquifer system functioning, the priority is thus to first fit the transmissivity field and to assess the distributed aquifer recharge accurately. The fitted DPBM, coupled with a linear model of coregionalization, is then used to quantify the hydrosystem water mass balance between 1974 and 2009, indicating that there is yet no trend of water resources decrease neither due to climate nor to human activities.

Quantification of the contribution of the Beauce groundwater aquifer to the discharge of the Loire River using thermal infrared satellite imaging

“…Eau-Dyssée is an integrated, distributed, process-based model that allows the simulation of the main components of the water cycle in a hydrosystem. Detailed descriptions of the model can be found in Flipo et al (2012) and Saleh et al (2011). This model has been applied to basins of different scales and hydrogeological settings, e.g., the Oise basin (4000 km 2 ; Saleh et al, 2011), the Rhône basin (86 500 km 2 ; Habets et al, 1999;Etchevers et al, 2001), the Seine basin (65 000 km 2 ; Ledoux et al, 2007;Pryet et al, 2015) and the Loire basin (120 000 km 2 ; Monteil, 2011).…”

“…For example, between the nuclear power plants of Dampierre and Saint-Laurent-des-Eaux, the Loire River temperature has been shown to be influenced by the groundwater discharge from the Beauce aquifer and the Val d'Orléans hydrogeological system (Alberic and Lepiller, 1998;Alberic, 2004;Moatar and Gailhard, 2006). The average discharge of the Beauce aquifer was previously quantified using hydrogeological numerical modeling (Monteil, 2011;Flipo et al, 2012) and was found to have an inter-annual average of approximately 10 m 3 s −1 . However, until now, field measurement data have not been used to accurately locate or quantify the groundwater discharge.…”

Continental hydrosystem modelling: the concept of nested stream–aquifer interfaces

“…The timescale to be considered also varies depending on the studied object (HZ itself or a sedimentary basin functioning) (Harvey, 2002). Estimating the stream-aquifer exchanges at a sedimentary basin scale then requires the combination of various processes with different characteristic times or periods covering a wide range of temporal orders of magnitude (Blöschl and Sivapalan, 1995;Cardenas, 2008b;Flipo et al, 2012;Massei et al, 2010): hour-day for river processes, year-decade for effective rainfall, decade-century for subsurface transit time. Mouhri et al (2013) proposed a multi-scale framework to study stream-aquifer interfaces.…”

Hydraulic head and groundwater ¹¹¹Cd content interpolations using empirical Bayesian kriging (EBK) and geo-adaptive neuro-fuzzy inference system (geo-ANFIS)

“…They are also used to initialize distributed models, which are critical tools nowadays for managing water resources at the basin scale (Perkins and Sophocleous, 1999;Billen et al, 2007;Flipo et al, 2007Flipo et al, , 2012Flipo et al, , 2014. As reported in Flipo et al (2012) many inverse methodologies in hydrogeology use hydraulic head maps as a pre-requisite (24 publications among 45). The mapping of hydraulic heads requires synchronous measurements, usually achieved with synchronous snapshot campaigns.…”

“…) are interested in understanding the behaviour of hydrosystems Flipo et al, 2012). Usually they first do experiments/observations in the field at specific locations and then try to distribute these observations/measurements both in space and time using modelling techniques that are based on abstractions.…”