Wading through a swamp of complete confusion: how to choose a method for estimating soil water retention parameters for crop models

Gijsman, Arjan J.; Jagtap, S. S.; Jones, James W.

doi:10.1016/s1161-0301(02)00098-9

Cited by 131 publications

(88 citation statements)

References 33 publications

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“…Large discrepancies have been reported between pedotransfer functions which are prone to distinct sources of uncertainties (Espino et al, 1996;Baroni et al, 2010;Gijsman et al, 2002). The first shortcoming concerns their representativeness of soil property variability.…”

Section: Pedotransfer Estimatesmentioning

confidence: 99%

Evaluation of land surface model simulations of evapotranspiration over a 12-year crop succession: impact of soil hydraulic and vegetation properties

Garrigues

Olioso

Calvet

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Evapotranspiration has been recognized as one of the most uncertain terms in the surface water balance simulated by land surface models. In this study, the SURFEX/ISBA-A-gs (Interaction Sol-BiosphereAtmosphere) simulations of evapotranspiration are assessed at the field scale over a 12-year Mediterranean crop succession. The model is evaluated in its standard implementation which relies on the use of the ISBA pedotransfer estimates of the soil properties. The originality of this work consists in explicitly representing the succession of crop cycles and inter-crop bare soil periods in the simulations and assessing its impact on the dynamics of simulated and measured evapotranspiration over a long period of time. The analysis focuses on key parameters which drive the simulation of ET, namely the rooting depth, the soil moisture at saturation, the soil moisture at field capacity and the soil moisture at wilting point. A sensitivity analysis is first conducted to quantify the relative contribution of each parameter on ET simulation over 12 years. The impact of the estimation method used to retrieve the soil parameters (pedotransfer function, laboratory and field methods) on ET is then analysed. The benefit of representing the variations in time of the rooting depth and wilting point is evaluated. Finally, the propagation of uncertainties in the soil parameters on ET simulations is quantified through a Monte Carlo analysis and compared with the uncertainties triggered by the mesophyll conductance which is a key above-ground driver of the stomatal conductance.This work shows that evapotranspiration mainly results from the soil evaporation when it is continuously simulated over a Mediterranean crop succession. This results in a high sensitivity of simulated evapotranspiration to uncertainties in the soil moisture at field capacity and the soil moisture at saturation, both of which drive the simulation of soil evaporation. Field capacity was proved to be the most influencing parameter on the simulation of evapotranspiration over the crop succession. The evapotranspiration simulated with the standard surface and soil parameters of the model is largely underestimated. The deficit in cumulative evapotranspiration amounts to 24 % over 12 years. The bias in daily daytime evapotranspiration is −0.24 mm day −1 . The ISBA pedotransfer estimates of the soil moisture at saturation and at wilting point are overestimated, which explains most of the evapotranspiration underestimation. The use of field capacity values retrieved from laboratory methods leads to inaccurate simulation of ET due to the lack of representativeness of the soil structure variability at the field scale. The most accurate simulation is achieved with the average values of the soil properties derived from the analysis of field measurements of soil moisture vertical profiles over each crop cycle. The representation of the variations in time of the wilting point and the maximum rooting depth over the crop succession has litPublished by Copernicus Publica...

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Section: Pedotransfer Estimatesmentioning

confidence: 99%

Evaluation of land surface model simulations of evapotranspiration over a 12-year crop succession: impact of soil hydraulic and vegetation properties

Garrigues

Olioso

Calvet

et al. 2015

Hydrol. Earth Syst. Sci.

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“…They demonstrated that the impact on the percolation at 1 m depth of the use of different PTFs was insignificant when the cumulative value at the end of the simulation period was considered, but was significant for the distribution of the percolation over the period. In Gijsman et al (2003) eight methods for estimating hydraulic parameters were compared using the functional approach for the prediction of crop yield by the CROP-GRO-Soybean model. The authors showed that the discrepancy between estimations is so high that it is hard to make recommendations on which methods to use for which soils.…”

Section: Introductionmentioning

confidence: 99%

Uncertainty in the determination of soil hydraulic parameters and its influence on the performance of two hydrological models of different complexity

Baroni

Facchi

Gandolfi

et al. 2010

Hydrol. Earth Syst. Sci.

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Abstract. Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still debated. However, we may wonder how the uncertainty in soil hydraulic parameters relates to the uncertainty of the selected modelling approach. We performed an intensive monitoring study during the cropping season of a 10 ha maize field in Northern Italy. The data were used to: i) compare different methods for determining soil hydraulic parameters and ii) evaluate the effect of the uncertainty in these parameters on different variables (i.e. evapotranspiration, average water content in the root zone, flux at the bottom boundary of the root zone) simulated by two hydrological models of different complexity: SWAP, a widely used model of soil moisture dynamics in unsaturated soils based on Richards equation, and ALHyMUS, a conceptual model of the same dynamics based on a reservoir cascade scheme. We employed five direct and indirect methods to determine soil hydraulic parameters for each horizon of the experimental profile. Two methods were based on a parameter optimization of: a) laboratory measured retention and hydraulic conductivity data and b) field measured retention and hydraulic conductivity data. The remaining three methods were based on the application of widely used Pedo-Transfer Functions: c) Rawls and Brakensiek, d) HYPRES, and e) ROSETTA. Simulations were performed using meteorological, irrigation and crop data measured at the experimental site during the period June -October 2006. Results showed a wide range of soil hydraulic parameter values generated with the different Correspondence to: G. Baroni (gabriele.baroni@email.it) methods, especially for the saturated hydraulic conductivity K sat and the shape parameter α of the van Genuchten curve. This is reflected in a variability of the modeling results which is, as expected, different for each model and each variable analysed. The variability of the simulated water content in the root zone and of the bottom flux for different soil hydraulic parameter sets is found to be often larger than the difference between modeling results of the two models using the same soil hydraulic parameter set. Also we found that a good agreement in simulated soil moisture patterns may occur even if evapotranspiration and percolation fluxes are significantly different. Therefore multiple output variables should be considered to test the performances of methods and models.

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“…Equations that generate layer-specific estimates for Db, Dp, FC, PWP and Ksat from generally available soil data such as OM, texture (i.e., sand, silt and clay content) and soil depth are known as "point pedotransfer functions", or point PTFs (Bouma, 1989;Gijsman et al 2003;Børgesen and Schaap 2005;Pachepsky and Rawls 2005;Schaap 2006;Børgesen et al 2007). The following equations (Balland et al 2008) were used to this effect: …”

Section: Estimating Soil Moisture Flow Retention and Ksatmentioning

confidence: 99%

Determining Hydraulic Conductivity from Soil Characteristics with Applications for Modelling Stream Discharge in Forest Catchments

Jutras¹,

Arp²

2011

Hydraulic Conductivity - Issues, Determination and Applications

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Wading through a swamp of complete confusion: how to choose a method for estimating soil water retention parameters for crop models

Cited by 131 publications

References 33 publications

Evaluation of land surface model simulations of evapotranspiration over a 12-year crop succession: impact of soil hydraulic and vegetation properties

Evaluation of land surface model simulations of evapotranspiration over a 12-year crop succession: impact of soil hydraulic and vegetation properties

Uncertainty in the determination of soil hydraulic parameters and its influence on the performance of two hydrological models of different complexity

Determining Hydraulic Conductivity from Soil Characteristics with Applications for Modelling Stream Discharge in Forest Catchments

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