scholarly journals Energy balance closure on a winter wheat stand: comparing the eddy covariance technique with the soil water balance method

2016 ◽  
Vol 13 (1) ◽  
pp. 63-75 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck
Keyword(s):  
Energy Balance ◽  
Water Balance ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Water Storage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Water Balance Method ◽  
Closure Method

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. In the present study we cross-checked the evapotranspiration data obtained with the EC method (ETEC) against ET rates measured with the soil water balance method (ETWB) at winter wheat stands in southwest Germany. During the growing seasons 2012 and 2013, we continuously measured, in a half-hourly resolution, latent heat (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. ETWB was estimated based on rainfall, seepage and soil water storage measurements. The soil water storage term was determined at sixteen locations within the footprint of an EC station, by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was additionally continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 growing season, the H post-closed LE flux data (ETEC =  3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 24 and 48 %, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 46 and 70 %, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most observation periods on our site, LE is not a major component of the energy balance gap. Our results indicate that the energy balance gap is made up by other energy fluxes and unconsidered or biased energy storage terms.

scholarly journals Energy balance closure on a winter wheat stand: comparing the eddy covariance technique with the soil water balance method

2015 ◽  
Vol 12 (9) ◽  
pp. 6783-6820 ◽  
Author(s):  
K. Imukova ◽  
J. Ingwersen ◽  
M. Hevart ◽  
T. Streck
Keyword(s):  
Energy Balance ◽  
Water Balance ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Eddy Covariance ◽  
Soil Water Balance ◽  
Flux Data ◽  
Closure Method

Abstract. The energy balance of eddy covariance (EC) flux data is typically not closed. The nature of the gap is usually not known, which hampers using EC data to parameterize and test models. The present study elucidates the nature of the energy gap of EC flux data from winter wheat stands in southwest Germany. During the vegetation periods 2012 and 2013, we continuously measured, in a half-hourly resolution, latent (LE) and sensible (H) heat fluxes using the EC technique. Measured fluxes were adjusted with either the Bowen-ratio (BR), H or LE post-closure method. The adjusted LE fluxes were tested against evapotranspiration data (ETWB) calculated using the soil water balance (WB) method. At sixteen locations within the footprint of an EC station, the soil water storage term was determined by measuring the soil water content down to a soil depth of 1.5 m. In the second year, the volumetric soil water content was also continuously measured in 15 min resolution in 10 cm intervals down to 90 cm depth with sixteen capacitance soil moisture sensors. During the 2012 vegetation period, the H post-closed LE flux data (ETEC = 3.4 ± 0.6 mm day−1) corresponded closest with the result of the WB method (3.3 ± 0.3 mm day−1). ETEC adjusted by the BR (4.1 ± 0.6 mm day−1) or LE (4.9 ± 0.9 mm day−1) post-closure method were higher than the ETWB by 20 and 33%, respectively. In 2013, ETWB was in best agreement with ETEC adjusted with the H post-closure method during the periods with low amount of rain and seepage. During these periods the BR and LE post-closure methods overestimated ET by about 30 and 40%, respectively. During a period with high and frequent rainfalls, ETWB was in-between ETEC adjusted by H and BR post-closure methods. We conclude that, at most vegetation periods on our site, LE is not a~major component of the energy balance gap. Our results indicate that the energy balance gap other energy fluxes and unconsidered or biased energy storage terms.

scholarly journals Comparison of the monitored and modeled soil water storage of the upper soil layer: the influence of soil properties and groundwater table level

2010 ◽  
Vol 58 (4) ◽  
pp. 279-283 ◽  
Author(s):  
Július Šútor ◽  
Vlasta Štekauerová ◽  
Viliam Nagy
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Soil Properties ◽  
Water Content ◽  
Soil Water ◽  
Soil Layer ◽  
Water Storage ◽  
Groundwater Table ◽  
Soil Water Balance ◽  
Soil Water Storage

Comparison of the monitored and modeled soil water storage of the upper soil layer: the influence of soil properties and groundwater table levelIn the study ofTomlain(1997) a soil water balance model was applied to evaluate the climate change impacts on the soil water storage in the Hurbanovo locality (Southwestern Slovakia), using the climate change scenarios of Slovakia for the years 2010, 2030, and 2075 by the global circulation models CCCM, GISS and GFD3. These calculations did not take into consideration neither the various soil properties, nor the groundwater table influence on soil water content. In this study, their calculated data were compared with those monitored at the same sites. There were found significant differences between resulting soil water storage of the upper 100 cm soil layer, most probably due to cappilary rise from groundwater at sites 2 and 3. It was shown, that the soil properties and groundwater table depth are importat features strongly influencing soil water content of the upper soil layer; thus the application of the soil water balance equation (Eq. (1)), neglecting the above mentioned factors, could lead to the results far from reality.

Using automated soil water content measurements to estimate soil water budgets

2006 ◽  
Vol 86 (1) ◽  
pp. 47-56 ◽  
Author(s):  
A. J. McCoy ◽  
G. Parkin ◽  
C. Wagner-Riddle ◽  
J. Warland ◽  
J. Lauzon ◽  
...  
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Soil Water ◽  
Water Storage ◽  
Conventional Tillage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Rain Event ◽  
The Difference ◽  
Ct System

The distribution of precipitation into the components of a soil water budget has a profound impact on crop growth, groundwater recharge, soil erosion, and groundwater and surface water contamination levels. The main objectives of this study were to develop a new method of measuring soil water balances and to demonstrate the use of the method in examining differences between partitioning of water in conventional tillage (CT) and no-tillage (NT) management systems. Hourly precipitation, evapotranspiration, and changes in soil water storage data were collected automatically over a 3-yr period at a field site near Elora, Ontario. Runoff and interception were calculated as the difference between measured increases in soil water storage and total rainfall during each significant rain event when the soil was not frozen. Drainage was then calculated, as it was the only component of the soil water balance not measured. The amount of soil water stored in the NT system was greater than the CT system during the latter part of the study as the NT system aged. The amount of drainage calculated for a 3 -yr period was greater for CT than the NT treatment, a result that is contrary to many previous studies. The measured amount of runoff plus interception was greater in the NT versus CT treatment. Since NT is generally accepted as a means of reducing runoff, this result could be due to the enhanced amount of interception by the crop residue left on the surface of the NT treatment. Key words: Soil water balance, water content reflectometer, drainage, runoff, tillage, time series

scholarly journals A stochastic approach for the description of the water balance dynamics in a river basin

2008 ◽  
Vol 12 (5) ◽  
pp. 1189-1200 ◽  
Author(s):  
S. Manfreda ◽  
M. Fiorentino
Keyword(s):  
Water Balance ◽  
Probability Density ◽  
Soil Water ◽  
Storage Capacity ◽  
Water Storage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Water Storage Capacity ◽  
Soil Water Storage Capacity ◽  
Balance Dynamics

Abstract. The present paper introduces an analytical approach for the description of the soil water balance dynamics over a schematic river basin. The model is based on a stochastic differential equation where the rainfall forcing is interpreted as an additive noise in the soil water balance. This equation can be solved assuming known the spatial distribution of the soil moisture over the basin transforming the two-dimensional problem in space in a one dimensional one. This assumption is particularly true in the case of humid and semihumid environments, where spatial redistribution becomes dominant producing a well defined soil moisture pattern. The model allowed to derive the probability density function of the saturated portion of a basin and of its relative saturation. This theory is based on the assumption that the soil water storage capacity varies across the basin following a parabolic distribution and the basin has homogeneous soil texture and vegetation cover. The methodology outlined the role played by the soil water storage capacity distribution of the basin on soil water balance. In particular, the resulting probability density functions of the relative basin saturation were found to be strongly controlled by the maximum water storage capacity of the basin, while the probability density functions of the relative saturated portion of the basin are strongly influenced by the spatial heterogeneity of the soil water storage capacity. Moreover, the saturated areas reach their maximum variability when the mean rainfall rate is almost equal to the soil water loss coefficient given by the sum of the maximum rate of evapotranspiration and leakage loss in the soil water balance. The model was tested using the results of a continuous numerical simulation performed with a semi-distributed model in order to validate the proposed theoretical distributions.

scholarly journals Water table effects on measured and simulated fluxes in weighing lysimeters for differently-textured soils

2015 ◽  
Vol 63 (1) ◽  
pp. 82-92 ◽  
Author(s):  
Martin Wegehenkel ◽  
Horst H. Gerke
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Water Table ◽  
Sandy Soil ◽  
Water Storage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Silty Clay ◽  
Bottom Boundary ◽  
Soil Hydraulic

Abstract Weighing lysimeters can be used for studying the soil water balance and to analyse evapotranspiration (ET). However, not clear was the impact of the bottom boundary condition on lysimeter results and soil water movement. The objective was to analyse bottom boundary effects on the soil water balance. This analysis was carried out for lysimeters filled with fine- and coarse-textured soil monoliths by comparing simulated and measured data for lysimeters with a higher and a lower water table. The eight weighable lysimeters had a 1 m2 grass-covered surface and a depth of 1.5 m. The lysimeters contained four intact monoliths extracted from a sandy soil and four from a soil with a silty-clay texture. For two lysimeters of each soil, constant water tables were imposed at 135 cm and 210 cm depths. Evapotranspiration, change in soil water storage, and groundwater recharge were simulated for a 3-year period (1996 to 1998) using the Hydrus-1D software. Input data consisted of measured weather data and crop model-based simulated evaporation and transpiration. Snow cover and heat transport were simulated based on measured soil temperatures. Soil hydraulic parameter sets were estimated (i) from soil core data and (ii) based on texture data using ROSETTA pedotransfer approach. Simulated and measured outflow rates from the sandy soil matched for both parameter sets. For the sand lysimeters with the higher water table, only fast peak flow events observed on May 4, 1996 were not simulated adequately mainly because of differences between simulated and measured soil water storage caused by ET-induced soil water storage depletion. For the silty-clay soil, the simulations using the soil hydraulic parameters from retention data (i) were matching the lysimeter data except for the observed peak flows on May, 4, 1996, which here probably resulted from preferential flow. The higher water table at the lysimeter bottom resulted in higher drainage in comparison with the lysimeters with the lower water table. This increase was smaller for the finer-textured soil as compared to the coarser soil.

scholarly journals General procedure to initialize the cyclic soil water balance by the Thornthwaite and Mather method

2010 ◽  
Vol 67 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Durval Dourado-Neto ◽  
Quirijn de Jong van Lier ◽  
Klaas Metselaar ◽  
Klaus Reichardt ◽  
Donald R. Nielsen
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
General Procedure ◽  
Water Storage ◽  
Dry Season ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Wet Season ◽  
Water Balance Components ◽  
Semi Arid

The original Thornthwaite and Mather method, proposed in 1955 to calculate a climatic monthly cyclic soil water balance, is frequently used as an iterative procedure due to its low input requirements and coherent estimates of water balance components. Using long term data sets to establish a characteristic water balance of a location, the initial soil water storage is generally assumed to be at field capacity at the end of the last month of the wet season, unless the climate is (semi-) arid when the soil water storage is lower than the soil water holding capacity. To close the water balance, several iterations might be necessary, which can be troublesome in many situations. For (semi-) arid climates with one dry season, Mendonça derived in 1958 an equation to quantify the soil water storage monthly at the end of the last month of the wet season, which avoids iteration procedures and closes the balance in one calculation. The cyclic daily water balance application is needed to obtain more accurate water balance output estimates. In this note, an equation to express the water storage for the case of the occurrence of more than one dry season per year is presented as a generalization of Mendonça's equation, also avoiding iteration procedures.

scholarly journals Comparison of real evapotranspiration measured by weighing lysimeters with simulations based on the Penman formula and a crop growth model

2013 ◽  
Vol 61 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Martin Wegehenkel ◽  
Horst H. Gerke
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Growth Model ◽  
Temporal Dynamics ◽  
Water Storage ◽  
Water Balance Model ◽  
Soil Water Balance ◽  
Balance Model ◽  
Soil Water Storage ◽  
Silty Clay

Abstract Although the quantification of real evapotranspiration (ETr) is a prerequisite for an appropriate estimation of the water balance, precision and uncertainty of such a quantification are often unknown. In our study, we tested a combined growth and soil water balance model for analysing the temporal dynamics of ETr. Simulated ETr, soil water storage and drainage rates were compared with those measured by 8 grass-covered weighable lysimeters for a 3-year period (January 1, 1996 to December 31, 1998). For the simulations, a soil water balance model based on the Darcy-equation and a physiological-based growth model for grass cover for the calculation of root water uptake were used. Four lysimeters represented undisturbed sandy soil monoliths and the other four were undisturbed silty-clay soil monoliths. The simulated ETr-rates underestimated the higher ETr-rates observed in the summer periods. For some periods in early and late summer, the results were indicative for oasis effects with lysimeter-measured ETr-rates higher than corresponding calculated rates of potential grass reference evapotranspiration. Despite discrepancies between simulated and observed lysimeter drainage, the simulation quality for ETr and soil water storage was sufficient in terms of the Nash-Sutcliffe index, the modelling efficiency index, and the root mean squared error. The use of a physiological-based growth model improved the ETr estimations significantly.

scholarly journals Validation of the ISAREG model for the irrigation management of the melon crop in the state of Ceará

2021 ◽  
Vol 9 (10) ◽  
pp. 119-130
Author(s):  
Kleiton Rocha Saraiva ◽  
Francisco Marcus Lima Bezerra ◽  
Francisco de Souza ◽  
Luis de França Camboim Neto ◽  
Clayton Moura de Carvalho ◽  
...  
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Irrigation Management ◽  
Water Storage ◽  
Crop Coefficient ◽  
The State ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Effective Depth ◽  
Soil Climate

The research aimed to validate the ISAREG model, introducing it to water management studies in irrigation in the State of Ceará, comparing results of experimental research, with results of simulations, carried out with the use of software, analyzing the following variables: crop evapotranspiration, variation of soil water storage and water flow in the soil. A bibliographic survey was carried out to obtain soil, climate and crop information required by the model to perform the soil water balance. Aiming at the validation of ISAREG, the model was fed with the following data: reference evapotranspiration, precipitation, phenological phases of the crop, effective depth of the root system, water availability factor in the soil, crop coefficient and soil information. Subsequently, the irrigation management option "dates and irrigation depths" was selected, and ISAREG performed the simulation of the soil water balance. The ISAREG demonstrated a detailed soil water balance, being validated in this study, because when its results were compared to the experimental ones, there was similarity in the trends of the variables analyzed, despite the reduced correlation verified regarding the variation of water storage in the soil.

scholarly journals The Effect of Cover Crops on Soil Water Balance in Rain-Fed Conditions

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 492 ◽  
Author(s):  
Đorđe Krstić ◽  
Svetlana Vujić ◽  
Goran Jaćimović ◽  
Paride D’Ottavio ◽  
Zoran Radanović ◽  
...  
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Cover Crops ◽  
Water Conservation ◽  
Cover Crop ◽  
Standardized Precipitation Index ◽  
Water Storage ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
Silage Maize

Soil and water conservation benefits of cover crops have been hypothesized as a way to mitigate and adapt to changing climatic conditions, but they can also have detrimental effects if rainfall is limited. Our objective was to quantify effects of winter cover crops on soil water storage and yield of silage maize under the agro-ecological conditions within Vojvodina Province in Serbia. The experiment was conducted under rain-fed conditions at three locations and included a control (bare fallow) plus three cover crop and two N rate treatments. The cover crop treatments were common vetch (Vicia sativa L.), triticale (x Triticosecale Wittm. ex A. Camus) and a mixture of the two species. All were managed as green manure and subsequently fertilized with either 120 or 160 kg N ha−1 before planting silage maize (Zea mays L.). Cover crop effects on soil water storage were calculated for two periods, March–May and May–September/October. A Standardized Precipitation Index (SPI) used to characterize drought severity for 2011/2012 and 2012/2013, showed values of 3 and 9, respectively, for the two periods. Soil water storage was reduced by all cover crop treatments, with the greatest deficiency occurring during the extremely dry year of 2012. Previous studies have shown cover crop growth reduced by soil water depletion during their growing season and negative effects on early-season growth and development of subsequent cash crops such as silage maize, but if rainfall is extremely low it can also reduce cash crop yield. This detrimental effect of cover crops on soil water balance was confirmed by correlations between soil water storage and maize silage yield.

scholarly journals Regression Models for Soil Water Storage Estimation Using the ESA CCI Satellite Soil Moisture Product: A Case Study in Northeast Portugal

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 37
Author(s):  
Tomás de Figueiredo ◽  
Ana Caroline Royer ◽  
Felícia Fonseca ◽  
Fabiana Costa de Araújo Schütz ◽  
Zulimar Hernández
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Regression Models ◽  
Meteorological Data ◽  
Water Storage ◽  
Model Performance ◽  
Soil Water Balance ◽  
Soil Water Storage ◽  
The Relationship

The European Space Agency Climate Change Initiative Soil Moisture (ESA CCI SM) product provides soil moisture estimates from radar satellite data with a daily temporal resolution. Despite validation exercises with ground data that have been performed since the product’s launch, SM has not yet been consistently related to soil water storage, which is a key step for its application for prediction purposes. This study aimed to analyse the relationship between soil water storage (S), which was obtained from soil water balance computations with ground meteorological data, and soil moisture, which was obtained from radar data, as affected by soil water storage capacity (Smax). As a case study, a 14-year monthly series of soil water storage, produced via soil water balance computations using ground meteorological data from northeast Portugal and Smax from 25 mm to 150 mm, were matched with the corresponding monthly averaged SM product. Linear (I) and logistic (II) regression models relating S with SM were compared. Model performance (r2 in the 0.8–0.9 range) varied non-monotonically with Smax, with it being the highest at an Smax of 50 mm. The logistic model (II) performed better than the linear model (I) in the lower range of Smax. Improvements in model performance obtained with segregation of the data series in two subsets, representing soil water recharge and depletion phases throughout the year, outlined the hysteresis in the relationship between S and SM.

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