Inversion of Root Zone Soil Hydraulic Parameters with Limited Calibration Data

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 methods, especially for the saturated hydraulic conductivity Ksat 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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Uncertainty in the determination of soil hydraulic parameters and its influence on the performance of two hydrological models of different complexity

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-4065-2009 ◽

2009 ◽

Vol 6 (3) ◽

pp. 4065-4105 ◽

Cited By ~ 3

Author(s):

G. Baroni ◽

A. Facchi ◽

C. Gandolfi ◽

B. Ortuani ◽

D. Horeschi ◽

...

Keyword(s):

Soil Moisture ◽

Hydraulic Conductivity ◽

Water Content ◽

Root Zone ◽

Hydraulic Parameters ◽

Hydrological Models ◽

Conductivity Data ◽

Hydraulic Parameter ◽

Soil Hydraulic Parameters ◽

Soil Hydraulic

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. These 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 outputs (i.e. evapotranspiration, water content in the root zone, fluxes through the bottom boundary of the root zone) of two hydrological models with 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 field. 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. 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 evaluated with the different methods, especially for the saturated hydraulic conductivity Ksat 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. The variability of the simulated water content in the root zone and of the fluxes at the root zone bottom 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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Estimation of root water uptake and soil hydraulic parameters from root zone soil moisture and deep percolation

Agricultural Water Management ◽

10.1016/j.agwat.2019.05.037 ◽

2019 ◽

Vol 222 ◽

pp. 38-47 ◽

Cited By ~ 3

Author(s):

Ickkshaanshu Sonkar ◽

Hari Prasad Kotnoor ◽

Sumit Sen

Keyword(s):

Soil Moisture ◽

Water Uptake ◽

Root Zone ◽

Root Water Uptake ◽

Hydraulic Parameters ◽

Deep Percolation ◽

Soil Hydraulic Parameters ◽

Soil Hydraulic

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Evaluation and improvement of the default soil hydraulic parameters for the Noah Land Surface Model

Geoderma ◽

10.1016/j.geoderma.2016.09.022 ◽

2017 ◽

Vol 285 ◽

pp. 247-259 ◽

Cited By ~ 20

Author(s):

Andrea Sz. Kishné ◽

Yohannes Tadesse Yimam ◽

Cristine L.S. Morgan ◽

Bright C. Dornblaser

Keyword(s):

Land Surface ◽

Land Surface Model ◽

Surface Model ◽

Hydraulic Parameters ◽

Soil Hydraulic Parameters ◽

Noah Land Surface Model ◽

Soil Hydraulic

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Exploring hydrological processes at a small agricultural catchment in the Czech Republic

10.5194/egusphere-egu21-4952 ◽

2021 ◽

Author(s):

Tailin Li ◽

Nina Noreika ◽

Jakub Jeřábek ◽

Tomáš Dostál ◽

David Zumr

Keyword(s):

Soil Moisture ◽

Soil Water ◽

Hydrological Processes ◽

Hydraulic Parameters ◽

Rainfall Runoff ◽

The Czech Republic ◽

Mike She ◽

Stream Discharge ◽

Soil Hydraulic Parameters ◽

Soil Hydraulic

A better understanding of hydrological processes in agricultural catchments is not only crucial to hydrologists but also helpful for local farmers. Therefore, we have built the freely-available web-based WALNUD dataset (Water in Agricultural Landscape &#8211; NU&#269;ice Database) for our experimental catchment Nu&#269;ice (0.53 km2), the Czech Republic. We have included observed precipitation, air temperature, stream discharge, and soil moisture in the dataset. Furthermore, we have applied numerical modelling techniques to investigate the hydrological processes (e.g. soil moisture variability, water balance) at the experimental catchment using the dataset.The Nu&#269;ice catchment, established in 2011, serves for the observation of rainfall-runoff processes, soil erosion and water balance of the cultivated landscape. The average altitude is 401 m a.s.l., the mean land slope is 3.9 %, and the climate is humid continental (mean annual temperature 7.9 &#176;C, average annual precipitation 630 mm). The catchment consists of three fields covering over 95 % of the area. There is a narrow stream which begins as a subsurface drainage pipe in the uppermost field draining the water at catchment. The typical crops are winter wheat, rapeseed, mustard and alfalfa. The installed equipment includes a standard meteorological station, several rain gauges distributed in the area of the basin, and an H flume to monitor the stream discharge, water turbidity and basic water quality indicators. The soil water content (at point scale) and groundwater level are also recorded. Recently, we have installed two cosmic-ray soil moisture sensors (StyX Neutronica) to estimate large-scale topsoil water content at the catchment.Even though the soil management and soil properties in the fields of Nu&#269;ice seem to be nearly homogeneous, we have observed variability in the topsoil moisture pattern. The method for the explanation of the soil water regime was the combination of the connectivity indices and numerical modelling. The soil moisture profiles from the point-scale sensors were processed in a 1-D physically-based soil water model (HYDRUS-1D) to optimize the soil hydraulic parameters. Further, the soil hydraulic parameters were used as input into a 3D spatially-distributed model, MIKE-SHE. The MIKE-SHE simulation has been mainly calibrated with rainfall-runoff observations. Meanwhile, the spatial patterns of the soil moisture were assessed from the simulation for both dry and wet catchment conditions. From the MIKE-SHE simulation, the optimized soil hydraulic parameters have improved the estimation of soil moisture dynamics and runoff generation. Also, the correlation between the observed and simulated soil moisture spatial patterns showed different behaviors during the dry and wet catchment conditions.This study has been supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS20/156/OHK1/3T/11 and the Project SHui which is co-funded by the European Union Project: 773903 and the Chinese MOST.

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