Time-dependent sensitivity and uncertainty analyses of an agro-climatic model for the water status management of vineyard

International audienceThis work describes the global sensitivity analysis (SA) of an agro-climatic model embedded in a decision support system (DSS) for the water status management of vineyard in the Languedoc-Roussillon region, France

Evaluation d'une approche multi-locale d'estimation spatiale de l'évapotranspiration sur un bassin versant agricole hétérogène en région méditerranéenne

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Evaluation of evapotransoiration on a small agricultural watershed: comparison of eddy correlation and scintillometry techniques

International audienc

Critical analysis of two approaches for modelling water transfers in the soil-vegetation-atmosphere continuum: application to vineyard

International audienceAims and Background: As part of a project on optimization of vineyard irrigation, we discuss the validity of two modeling approaches for soil-water transfers in terms of accuracy and parameterization cost. We compared an empirical ‘bucket-like’ model to an innovative 1D model (M2), based on a dual porosity nonrigid aggregated representation of the soil-water medium. Methods: The two models are coupled to the same canopy growth and radiation absorption models. Root water uptake is described as a bilinear change in relative transpiration rate as a function of the fraction of extractible soil water. The accuracy of the two models was evaluated in vineyards varying in soil type, rooting depth and irrigation procedure in the Languedoc region (France), by comparing soil moisture and predawn leaf potential, a reference indicator of soil water deficit. Results: A sensitivity analysis shows that, provided an accurate estimate of rooting depth, both approaches give relevant and similar results. M2 is robust to most of the hard-to-obtain parameters as root repartition versus depth. However, the two models calculated very different water losses by deep drainage out of the root zone. Conclusion: Considering the robustness of M2 to parameters uncertainty, we privilege it as a decision-support tool for irrigation, and as a ground for further modeling developments

Comparison of two modeling approaches for water transfer in the soil-vegetation-atmosphere continuum

As part of a R&D project aiming at providing vineyard managers with a computer-based decision support system for optimizing irrigation, we discuss the validity of two modeling approaches for water transfers in the soil-plant-atmosphere continuum. The two models are an empirical ‘bucketlike’ model and a mechanistic model based on the 1D Richards’ equation. The practical context implying that soil-water parameters are poorly estimated, both models are compared in terms of accuracy and parameterization cost. The models are coupled to the same canopy growth, radiation absorption, evaporation and transpiration models, and the predawn leaf water potential (PLWP) is used as the indicator of soil-water deficit. The parameters of both models are estimated with pedotransfer functions from the single texture and the only additional input for the 1D model is root repartition versus depth. A multi-factor sensitivity analysis relative to the input parameters of the soil-vegetation-atmosphere coupling shows that the hard-to-obtain rooting depth is the key factor of the PLWP sensitivity. It also shows that the computation of PLWP with the 1D model is robust against root distribution uncertainty, so that root distribution can be fixed to a mean value. The accuracy of the two models is evaluated in vineyards varying in soil type, rooting depth and irrigation procedure in the Languedoc region (France), by comparing simulated to measured values of vine transpiration and PLWP. Provided the calibration of rooting depth, both models give results coherent with field measurements, with no significant improvement when the more physical mechanistic model is used

Modelling evapotranspiration at the watershed scale using a multi-local approach

National audienc

Modélisation de l'évapotranspiration d'un petit bassin versant à l'aide d'une approche multi-locale

National audienc

Modelling evapotranspiration at the watershed scale using a multi-local approach

International audienc

A model-driven decision support system for vineyard water status management: a time-dependent sensitivity analysis

International audienceThe global sensitivity analysis of a dynamic soil water balance model embedded in a Decision Support System for vineyard water management is achieved via the Sobol variance-based method. The sensitivity analysis is applied sequentially at each simulation step so that the variation of parameter influence over time can be followed. Results allow identification of four soil-related parameters having the highest influence at the vine plot scale, and for various climate scenarios. This provides fundamental information for the operational use of the model, i.e. when few input data are available to the end-user

A decision-support system for vineyard water status management based on a modeling approach

International audienc