Using a multiobjective approach to retrieve information on surface properties used in a SVAT model

Demarty, Jérôme; Ottlé, Catherine; Braud, Isabelle; Olioso, Albert; Frangi, Jean-Pierre; Bastidas, L. A.; Gupta, H. V.

doi:10.1016/j.jhydrol.2003.10.003

Cited by 57 publications

(64 citation statements)

References 42 publications

(54 reference statements)

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“…Only two contrasted hydrological years (1 May 2006-30 April 2008 are used for calibration, the 5 remaining years being devoted to validation. Calibration is performed using a heuristic, stratified approach derived from prior sensitivity investigation, previous experience with the model (Braud, 1998;Boulet et al, 1999;Demarty et al, 2004Demarty et al, , 2005, results from similar experiments (e.g., Ridler et al, 2012), and an understanding of the physics of the various processes involved (see e.g., Cappelaere et al, 2009). All observed variables that are sensitive to a subset of parameters being calibrated are used for this purpose, at a half-hourly timestep, with the aim of achieving the best compromise between these variables given their observability (accuracy, representativity).…”

Section: Appendix A: Model Parameter Assignment Methodologymentioning

confidence: 99%

“…Model overview diagrams are provided by Fig. 1 in Demarty et al (2004) and Fig. 6.2 in Velluet (2014).…”

Section: Model Principlesmentioning

confidence: 99%

“…The SiSPAT model solves the 1-D vertical equations for coupled diffusive transfers of water and heat in a heterogeneous soil, coupled with surface and plant exchanges with the atmosphere. It has been shown (Demarty et al, 2004;Shin et al, 2012) that even in the general heterogeneous, layered case, this type of soil water model can be reliably inverted for hydrodynamic properties from soil moisture observations when the profile is predominantly draining (no underlying moisture source), which is the case in nearly all of this region. SiSPAT has already been tested successfully over a short period in this environment (Braud et al, 1997;Braud, 1998).…”

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confidence: 99%

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Building a field- and model-based climatology of local water and energy cycles in the cultivated Sahel – annual budgets and seasonality

Velluet

Demarty

Cappelaere

et al. 2014

Hydrol. Earth Syst. Sci.

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Abstract. In the sub-Saharan Sahel, energy and water cycling at the land surface is pivotal for the regional climate, water resources and land productivity, yet it is still very poorly documented. As a step towards a comprehensive climatological description of surface fluxes in this area, this study provides estimates of long-term average annual budgets and seasonal cycles for two main land use types of the cultivated Sahelian belt: rainfed millet crop and fallow bush. These estimates build on the combination of a 7-year field data set from two typical plots in southwestern Niger with detailed physically based soil-plant-atmosphere modeling, yielding a continuous, comprehensive set of water and energy flux and storage variables over this multiyear period. In the present case in particular, blending field data with mechanistic modeling makes the best use of available data and knowledge for the construction of the multivariate time series. Rather than using the model only to gap-fill observations into a composite series, model-data integration is generalized homogeneously over time by generating the whole series with the entire data-constrained model simulation. Climatological averages of all water and energy variables, with associated sampling uncertainty, are derived at annual to subseasonal scales from the time series produced. Similarities and differences in the two ecosystem behaviors are highlighted. Mean annual evapotranspiration is found to represent ∼ 82-85 % of rainfall for both systems, but with different soil evaporation/plant transpiration partitioning and different seasonal distribution. The remainder consists entirely of runoff for the fallow, whereas drainage and runoff stand in a 40-60 % proportion for the millet field. These results should provide a robust reference for the surface energy-and water-related studies needed in this region. Their significance and the benefits they gain from the innovative data-model integration approach are thoroughly discussed. The model developed in this context has the potential for reliable simulations outside the reported conditions, including changing climate and land cover.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Section: Appendix A: Model Parameter Assignment Methodologymentioning

confidence: 99%

“…Model overview diagrams are provided by Fig. 1 in Demarty et al (2004) and Fig. 6.2 in Velluet (2014).…”

Section: Model Principlesmentioning

confidence: 99%

mentioning

confidence: 99%

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Building a field- and model-based climatology of local water and energy cycles in the cultivated Sahel – annual budgets and seasonality

Velluet

Demarty

Cappelaere

et al. 2014

Hydrol. Earth Syst. Sci.

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“…They (and others) argue that the complexity of land-surface models needs to be reduced in order to eliminate the equifinality problem. Demarty et al (2004) applied a multi-objective approach for retrieving quantitative information about the surface properties from different surface measurements to determine the potential of a land-surface model to be applied with "little" a-priori information, and their results suggested that complex LSMs can be driven with limited a priori information. Future research along these lines may help to gain more insight in the problem of equifinality for advanced landsurface models.…”

Section: Single or Two-layer Modelsmentioning

confidence: 99%

Land-surface modelling in hydrological perspective – a review

2006

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Abstract. The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches, because in comparison to the traditional potential evapotranspiration models, these approaches allow for a stronger link to remote sensing and atmospheric modelling. New opportunities for evaluation of distributed land-surface models through application of remote sensing are discussed in detail, and the difficulties inherent in various evaluation procedures are presented. Finally, the dynamic coupling of hydrological and atmospheric models is explored, and the perspectives of such efforts are discussed.

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“…These models are essentially mathematical representations of 1-dimensional "views" of the increasingly complex physical mechanisms governing radiative, turbulent and water transfers [6]. They require a large set of input parameters and initial state variables, some of which are spatially and temporally very variable, where in general, model complexity and the number of parameters increase simultaneously [7]. Some SVAT models provide a framework for assessing the spatial variability of mass and energy exchanges by combining the remotely sensed surface conditions within a Surface Temperature (Ts) and Vegetation Index (VI) feature space with a land surface process model to derive regional maps of energy fluxes [8].…”

Section: Introductionmentioning

confidence: 99%

Extending the Global Sensitivity Analysis of the SimSphere model in the Context of its Future Exploitation by the Scientific Community

Petropoulos

Ireland

Griffiths

et al. 2015

Water

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In today's changing climate, the development of robust, accurate and globally applicable models is imperative for a wider understanding of Earth's terrestrial biosphere. Moreover, an understanding of the representation, sensitivity and coherence of such models are vital for the operationalisation of any physically based model. A Global Sensitivity Analysis (GSA) was conducted on the SimSphere land biosphere model in which a meta-modelling method adopting Bayesian theory was implemented. Initially, effects of assuming uniform probability distribution functions (PDFs) for the model inputs, when examining sensitivity of key quantities simulated by SimSphere at different output times, were examined. The development of topographic model input parameters (e.g., slope, aspect, and elevation) were derived within a Geographic Information System (GIS) before implementation within the model. The effect of time of the simulation on the sensitivity of previously examined outputs was also analysed. Results showed that simulated outputs were significantly influenced by changes in topographic input parameters, fractional vegetation cover, vegetation height and surface moisture availability in agreement with previous studies. Time of model output simulation had a significant influence on the absolute values OPEN ACCESSWater 2015, 7 2102 of the output variance decomposition, but it did not seem to change the relative importance of each input parameter. Sensitivity Analysis (SA) results of the newly modelled outputs allowed identification of the most responsive model inputs and interactions. Our study presents an important step forward in SimSphere verification given the increasing interest in its use both as an independent modelling and educational tool. Furthermore, this study is very timely given on-going efforts towards the development of operational products based on the synergy of SimSphere with Earth Observation (EO) data. In this context, results also provide additional support for the potential applicability of the assimilation of spatial analysis data derived from GIS and EO data into an accurate modelling framework.

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Using a multiobjective approach to retrieve information on surface properties used in a SVAT model

Cited by 57 publications

References 42 publications

Building a field- and model-based climatology of local water and energy cycles in the cultivated Sahel – annual budgets and seasonality

Building a field- and model-based climatology of local water and energy cycles in the cultivated Sahel – annual budgets and seasonality

Land-surface modelling in hydrological perspective – a review

Extending the Global Sensitivity Analysis of the SimSphere model in the Context of its Future Exploitation by the Scientific Community

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