On the uncertainty of initial condition and initialization approaches in variably saturated flow modeling

Abstract. Soil water movement is quite important due to its direct effects on environment, agriculture and hydrology. Simulation of soil water movement requires accurate determination of model parameters as well as initial and boundary conditions. However, it is difficult to obtain the accurate initial soil moisture/matric potential profile at the beginning of simulation time, making it necessary to run the simulation model from arbitrary initial condition until the uncertainty of initial condition (UIC) is diminished. The behavior of this process is usually defined as “warming up”. In this paper, two common methods in quantifying the UIC (one is based on running a single simulation recursively across multiple hydrological years, and the other is based on Monte-Carlo simulations with various initial condition) are compared and the required “warm-up” time twu (minimum time required for model to warm up to eliminate the UIC) is identified with different soil textures, meteorological conditions, and soil profile lengths. Then we analyze the effects of different initial conditions on parameter estimation within two data assimilation frameworks (i.e, ensemble Kalman filter and iterative ensemble smoother), and assess several existing model initializing methods to obtain initial condition based on the availability of data related to the retrieval of initial soil moisture profile. Results reveal that Monte-Carlo simulations and the recursive simulation over many years can both demonstrate the temporal behavior of UIC and a common threshold is recommended to determine the warm-up time for both methods. Besides, the relationship between warm-up time for variably saturated flow modeling and the model settings (soil textures, meteorological conditions and soil profile length) are quantitatively identified. In addition, we propose a “warm-up” period before assimilating data in order to obtain a better performance of parameter and state estimation.

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On the uncertainty of initial condition and initialization approaches in variably saturated flow modeling

Hydrology and Earth System Sciences ◽

10.5194/hess-23-2897-2019 ◽

2019 ◽

Vol 23 (7) ◽

pp. 2897-2914 ◽

Cited By ~ 8

Author(s):

Danyang Yu ◽

Jinzhong Yang ◽

Liangsheng Shi ◽

Qiuru Zhang ◽

Kai Huang ◽

...

Keyword(s):

Monte Carlo ◽

Soil Moisture ◽

Water Movement ◽

Initial Conditions ◽

Meteorological Conditions ◽

Initial Condition ◽

Flow Modeling ◽

Warm Up ◽

Initial Soil ◽

Soil Water Movement

Abstract. Soil water movement has direct effects on environment, agriculture and hydrology. Simulation of soil water movement requires accurate determination of model parameters as well as initial and boundary conditions. However, it is difficult to obtain the accurate initial soil moisture or matric potential profile at the beginning of simulation time, making it necessary to run the simulation model from the arbitrary initial condition until the uncertainty of the initial condition (UIC) diminishes, which is often known as “warming up”. In this paper, we compare two commonly used methods for quantifying the UIC (one is based on running a single simulation recursively across multiple hydrological years, and the other is based on Monte Carlo simulations with realization of various initial conditions) and identify the warm-up time twu (minimum time required to eliminate the UIC by warming up the model) required with different soil textures, meteorological conditions and soil profile lengths. Then we analyze the effects of different initial conditions on parameter estimation within two data assimilation frameworks (i.e., ensemble Kalman filter and iterative ensemble smoother) and assess several existing model initializing methods that use available data to retrieve the initial soil moisture profile. Our results reveal that Monte Carlo simulations and the recursive simulation over many years can both demonstrate the temporal behavior of the UIC, and a common threshold is recommended to determine twu. Moreover, the relationship between twu for variably saturated flow modeling and the model settings (soil textures, meteorological conditions and soil profile length) is quantitatively identified. In addition, we propose a warm-up period before assimilating data in order to obtain a better performance for parameter and state estimation.

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Sensitivity of LISEM predicted catchment discharge to initial soil moisture content of soil profile

Journal of Hydrology ◽

10.1016/j.jhydrol.2010.08.016 ◽

2010 ◽

Vol 393 (3-4) ◽

pp. 174-185 ◽

Cited By ~ 18

Author(s):

Vahedberdi Sheikh ◽

Emiel van Loon ◽

Rudi Hessel ◽

Victor Jetten

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Profile ◽

Soil Moisture Content ◽

Initial Soil Moisture ◽

Initial Soil

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Soil water movement under a bottomland hedgerow during contrasting meteorological conditions

Hydrological Processes ◽

10.1002/hyp.7909 ◽

2010 ◽

Vol 25 (9) ◽

pp. 1431-1442 ◽

Cited By ~ 9

Author(s):

R. Ghazavi ◽

Z. Thomas ◽

Y. Hamon ◽

Ph. Merot

Keyword(s):

Soil Water ◽

Water Movement ◽

Meteorological Conditions ◽

Soil Water Movement

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Application of Monte Carlo Method to Soil Water Movement

Transactions of the ASAE ◽

10.13031/2013.38035 ◽

1972 ◽

Vol 15 (5) ◽

pp. 0897-0901 ◽

Cited By ~ 3

Author(s):

Sun-Fu Shih and George J. Kriz

Keyword(s):

Monte Carlo ◽

Monte Carlo Method ◽

Soil Water ◽

Water Movement ◽

Soil Water Movement

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Improved meteorology and surface energy fluxes in mesoscale modelling using adjusted initial vertical soil moisture profiles

10.5194/hess-2017-620 ◽

2017 ◽

Author(s):

Igor Gómez ◽

Vicente Caselles ◽

María José Estrela ◽

Juan Manuel Sánchez ◽

Eva Rubio ◽

...

Keyword(s):

Soil Moisture ◽

Surface Energy ◽

Soil Profile ◽

Mesoscale Modelling ◽

Energy Fluxes ◽

Soil Layers ◽

Surface Energy Fluxes ◽

Initial Soil Moisture ◽

Initial Soil

Abstract. The Regional Atmospheric Modeling System (RAMS) is being used for different and diverse purposes, ranging from atmospheric and dispersion of pollutants forecasting to agricultural meteorology and ecological modelling as well as for hydrological purposes, among others. The current paper presents a comprehensive assessment of the RAMS forecasts, comparing the results not only with observed standard surface meteorological variables, measured at FLUXNET stations and other portable and permanent weather stations located over the region of study, but also with non-standard observed variables, such as the surface energy fluxes, with the aim of evaluating the surface energy budget and its relation with a proper representation of standard observations and key physical processes for a wide range of applications. In this regard, RAMS is assessed against in-situ surface observations during a selected period within July 2011 over Eastern Spain. In addition, the simulation results are also compared with different surface remote sensing data derived from the Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) (MSG-SEVIRI) as well as the uncoupled Land Surface Models (LSM) Global Land Data Assimilation System (GLDAS). Both datasets complement the available in-situ observations and are used in the current study as the reference or ground truth when no observations are available on a selected location. Several sensitivity tests have been performed involving the initial soil moisture content, by adjusting this parameter in the vertical soil profile ranging from the most superficial soil layers to those located deeper underground. A refined adjustment of this parameter in the initialization of the model has shown to better represent the observed surface energy fluxes. The results obtained also show an improvement in the model forecasts found in previous studies in relation to standard observations, such as the air temperature and the moisture fields. Therefore, the application of a drier or wetter soil in distinct soil layers within the whole vertical soil profile has been found to be crucial in order to produce a better agreement between the simulation and the observations, thus reiterating the determining role of the initial soil moisture field in mesoscale modelling, but in this case considering the variation of this parameter vertically.

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Soil water movement under a drip irrigation double-point source

Water Science & Technology Water Supply ◽

10.2166/ws.2015.045 ◽

2015 ◽

Vol 15 (5) ◽

pp. 924-932

Author(s):

Lizhu Hou ◽

Jie Shang ◽

Jiangtao Liu ◽

Haiyuan Lu ◽

Zhiming Qi

Keyword(s):

Soil Moisture ◽

Point Source ◽

Soil Water ◽

Drip Irrigation ◽

Double Point ◽

Water Movement ◽

Time Domain Reflectometry ◽

Runoff Water ◽

Surface Drip Irrigation ◽

Soil Water Movement

Particularly in dry regions, the scarcity of high-quality fresh water has heightened the importance of urban runoff water re-use, leading as well to the improvement of water use efficiency through the surface drip irrigation method. Given the limited research on wetting front migration under a surface drip irrigation emitter, soil water movement under a double-point-source irrigation emitter was investigated. An experimental soil bin was designed and filled with silt loam soil, and time domain reflectometry and tensiometers were used to measure soil moisture contents and soil water potential, respectively. The results show that under the conditions of 6 hours of irrigation with two drippers each delivering 1.05 L hr−1 and spaced at 45 cm, the soil moisture content of the 0–30 cm layer increased rapidly and reached 0.29 cm3 cm−3, and was greater than that in the 30–60 cm layer as irrigation proceeded. After 6 hours the irrigation was stopped, such that in the redistribution phase, soil moisture of the top layer gradually decreased, while that of the sublayer gradually increased. The results indicate that 6 hours of irrigation under given emitter flow conditions produced adequate soil moisture down to 30 cm for most shallow-rooted crops.

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SOIL WATER MOVEMENT MODELLING IN HAPLLICC LUVISOLS (HMM) AND ALBI HAPLLIC LUVISOLS (HML) UNDER SLOVAK CLIMATIC CONDITIONS

Journal of Environmental Engineering and Landscape Management ◽

10.3846/16486897.2007.9636911 ◽

2007 ◽

Vol 15 (2) ◽

pp. 69-75 ◽

Cited By ~ 3

Author(s):

Iveta Tóthová ◽

Dušan Igaz ◽

Jaroslav Antal

Keyword(s):

Soil Moisture ◽

Correlation Analysis ◽

Sugar Beet ◽

Time Domain ◽

Water Movement ◽

Gravimetric Method ◽

Climatic Conditions ◽

Global Model ◽

The Other ◽

Soil Water Movement

The aim of the research paper is simulation by the Global Model on the basis of investigation of Slovak Agricultural University (SAU) on two localities (Kolínany and Malanta). The soil moisture was measured by a time domain transmissometry instrument and compared with simulated outputs of the Global Model on Kolínany locality. Measurement of the soil moisture using the gravimetric method was applied on Malanta locality. Sugar beet was grown in Kolínany and, on the other hand, there was no plant on Malanta soil during the experiment. The experiment took three years (2002–2004). Measured and simulated courses of water content were consequently tested by correlation analysis in MS Excel. Result differences between simulated and measured values should reach according to 15 % difference at least 80 % of equality. Correlation between measured and simulated values had a high significance on Kolínany locality (in the range of 0,62–0,90) Equality between measured and simulated values was from 33 % to 75 % according to difference of 15 %.

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