Journal articles on the topic 'Soil water;hydraulic properties;water balance'
To see the other types of publications on this topic, follow the link: Soil water;hydraulic properties;water balance.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Soil water;hydraulic properties;water balance.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Cresswell, HP, DE Smiles, and J. Williams. "Soil structure, soil hydraulic properties and the soil water balance." Soil Research 30, no. 3 (1992): 265. http://dx.doi.org/10.1071/sr9920265.
Full textAbstract:
We review the influence of soil structural change on the fundamental soil hydraulic properties (unsaturated hydraulic conductivity and the soil moisture characteristic) and utilize deterministic modelling to assess subsequent effects on the soil water balance. Soil structure is reflected in the 0 to -100 kPa matric potential section of the soil moisture characteristic with marked changes often occurring in light to medium textured soils' (sands, sandy-loam, loams and clay-loams). The effect of long-term tillage on soil structure may decrease hydraulic conductivity within this matric potential range. The 'SWIM' (Soil Water Infiltration and Movement) simulation model was used to illustrate the effects of long-term conventional tillage and direct drilling systems on the water balance. The effects of plough pans, surface crusts and decreasing surface detention were also investigated. Significant structural deterioration, as evidenced by substantially reduced hydraulic conductivity, is necessary before significant runoff is generated in the low intensity rainfall regime of the Southern Tablelands (6 min rainfall intensity <45 mm h-1). A 10 mm thick plough pan (at a depth of 100 mm) in the A-horizon of a long-term conventionally tilled soil required a saturated hydraulic conductivity (K,) of less than 2.5 mm h-1 before runoff exceeded 10% of incident rainfall in this rainfall regime. Similarly, a crust K, of less than 2.5 mm h-1 was necessary before runoff exceeded 10% of incident rainfall (provided that surface detention was 2 or more). As the crust K, approached the rainfall rate, small decreases in Ks resulted in large increases in runoff. An increase in surface detention of 1 to 3 mm resulted in a large reduction in runoff where crust K, was less than 2-5 mm h-1. Deterministic simulation models incorporating well established physical laws are effective tools in the study of soil structural effects on the field water regime. Their application, however, is constrained by insufficient knowledge of the fundamental hydraulic properties of Australian soils and how they are changing in response to our land management.
2
Connolly, R. D., M. Bell, N. Huth, D. M. Freebairn, and G. Thomas. "Simulating infiltration and the water balance in cropping systems with APSIM-SWIM." Soil Research 40, no. 2 (2002): 221. http://dx.doi.org/10.1071/sr01007.
Full textAbstract:
We test APSIM-SWIM's ability to simulate infiltration and interactions between the soil water balance and grain crop growth using soil hydraulic properties derived from independent, point measurements. APSIMSWIM is a continuous soil-crop model that simulates infiltration, surface crusting, and soil condition in more detail than most other soil-crop models. Runoff, soil water, and crop growth information measured at sites in southern Queensland was used to test the model. Parameter values were derived directly from soil hydraulic properties measured using rainfall simulators, disc permeameters and ponded rings, and pressure plate apparatus. In general, APSIM-SWIM simulated infiltration, runoff, soil water and the water balance, and yield as accurately and reliably as other soil crop models, indicating the model is suitable for evaluating effects of infiltration and soil-water relations on crop growth. Increased model detail did not hinder application, instead improving parameter transferability and utility, but improved methods of characterising crusting, soil hydraulic conductivity, and macroporosity under field conditions would improve ease of application, prediction accuracy, and reliability of the model. Model utility and accuracy would benefit from improved representation of temporal variation in soil condition, including effects of tillage and consolidation on soil condition and bypass flow in cracks. infiltration, crop models, APSIM, water balance, soil structure.
3
Oliver, Y. M., and K. R. J. Smettem. "Predicting water balance in a sandy soil: model sensitivity to the variability of measured saturated and near saturated hydraulic properties." Soil Research 43, no. 1 (2005): 87. http://dx.doi.org/10.1071/sr03146.
Full textAbstract:
Water balance modelling based on Richards’ equation requires accurate description of the soils’ hydraulic parameters. Unfortunately, these parameters vary spatially and temporally as well as between measurement techniques. For most field modelling exercises, the hydraulic parameters are obtained from a small number of measurements or predicted from soil properties using pedo-transfer functions. The effect of different measurement techniques on the description of soil hydraulic parameters has been the subject of many studies but the effect of the variability of the hydraulic parameters on the predicted water balance has not been widely investigated. In this study we compared the hydraulic parameters obtained solely from laboratory measurements with those obtained from a rapid wet end field measurement technique, augmented by dry end laboratory data. The water balance was modelled using the laboratory and field hydraulic parameter sets and compared to field water contents measured by time domain reflectometry (TDR). In a sandy soil, we found the total profile water content to be well modelled by both hydraulic parameter datasets, but the water content at a specific depth was less well predicted using either of the measured parameter sets. The water content at a specific depth was under-predicted prior to the rainfall event and over-predicted after the rainfall, regardless of whether the hydraulic parameters were obtained from laboratory or field measurements. Generally, the hydraulic parameters that were obtained from the field measurements gave a closer fit to the measured TDR water contents. The sensitivity of the modelled water balance to changes in the hydraulic parameters within the observed range of parameter values was also investigated. Parameter percentage coefficient of variation within measurement techniques ranged from 60% for air entry, he; 19% for residual water content, θr; 5% for slope of the water retention curve, n; and 7% for saturated water content, θs. The percentage differences between the parameters obtained from the laboratory and field measurement techniques for the topsoil and subsoil respectively were 47% and 50% for he, 100% for θr, 28% and 40% for n, and –14.4% and 4.0% for θs. Modelling water content changes at a particular depth in the sandy soil was found to be most influenced by variations in θs, and n. Predicted water contents were also affected by the θr but less influenced by the saturated hydraulic conductivity, Ks. The he was the least influential parameter but also the most variable. This suggests that measurement of θs, related to bulk density changes caused by tillage, wheel compaction, and consolidation, is required for water balance studies. Generally, n had small variability between measurements at a particular depth, which is promising for the use of pedo-transfer functions related to soil texture.
4
Smettem, K. R. J., and K. L. Bristow. "Obtaining soil hydraulic properties for water balance and leaching models from survey data. 2. Hydraulic conductivity." Australian Journal of Agricultural Research 50, no. 7 (1999): 1259. http://dx.doi.org/10.1071/ar97075.
Full textAbstract:
Regional scale application of water and solute transport models is often limited by the lack of available data describing soil hydraulic properties and their variability. Direct measurement over large areas is expensive and time consuming. Physico-empirical models derived from soil survey data are therefore an attractive alternative. If the Marshall method of estimating the saturated hydraulic conductivity is simplified to depend primarily on the maximum pore radius, given by the bubbling pressure, then it is equivalent to the Campbell model of saturated hydraulic conductivity which relies entirely on an estimate of the bubbling pressure obtained from particle size data. We apply this simplified physico-empirical model to estimate the ‘matrix’, or textural saturated hydraulic conductivity, K m, using estimates of the bubbling pressure derived entirely from clay content data that are readily available in soil surveys. Model estimates are compared with in situ measurements on surface soils obtained using a disc permeameter with a negative pressure head at the supply surface of 40 mm. Results appear to be satisfactory for broad-scale water balance and leaching risk models that require specification of a matching point for the unsaturated hydraulic conductivity function and for modelling applications requiring generalised application of results from experimental sites.
5
Smettem, K. R. J., K. L. Bristow, L. K. Heng, Y. M. Oliver, and E. J. Ford. "Obtaining soil hydraulic properties for water balance and leaching models from survey data. 1. Water retention." Australian Journal of Agricultural Research 50, no. 2 (1999): 283. http://dx.doi.org/10.1071/a97074.
Full textAbstract:
A physico-empirical 2-parameter power law model of the draining water retention curve (WRC) based solely on clay content is described and further developed using 6 datasets obtained from Australian and New Zealand soils. The slope of the WRC, or pore-size distribution index, is well described by the model but the bubbling pressure, or inflection point is poorly described. Without a good estimation of the bubbling pressure it is not possible to scale the physico-empirical model to the WRC. To achieve the scaling, a single measured point on the WRC in the unsaturated range is required. The resulting estimated water contents may be satisfactory for application within broad-scale leaching risk models and for generalised extrapolation of results from detailed experimental sites but caution is still required for quantitative applications of nitrate leaching models at a particular site. It is concluded that soil surveys could usefully include a single WRC measurement in the field at each sampling location to improve their utility for water and chemical transport modelling.
6
Mohajerani, Hadis, Sonja Teschemacher, and Markus C. Casper. "A Comparative Investigation of Various Pedotransfer Functions and Their Impact on Hydrological Simulations." Water 13, no. 10 (May 17, 2021): 1401. http://dx.doi.org/10.3390/w13101401.
Full textAbstract:
Soil hydraulic properties, which are basically saturated and unsaturated hydraulic conductivity and water retention characteristics, remarkably control the main hydrological processes in catchments. Thus, adequate parameterization of soils is one of the most important tasks in physically based catchment modeling. To estimate these properties, the choice of the PTFs in a hydrological model is often made without taking the runoff characteristics of the catchment into consideration. Therefore, this study introduces a methodology to analyze the sensitivity of a catchment water balance model to the choice of the PTF. To do so, we define 11 scenarios including different combinations of PTFs to estimate the van Genuchten parameters and saturated hydraulic conductivity. We use a calibrated/validated hydrological model (WaSiM-ETH) as a baseline scenario. By altering the underlying PTFs, the effects on the hydraulic properties are quantified. Moreover, we analyze the resulting changes in the spatial/temporal variation of the total runoff and in particular, the runoff components at the catchment outlet. Results reveal that the water distribution in the hydrologic system varies considerably amongst different PTFs, and the water balance components are highly sensitive to the spatial structure of soil hydraulic properties. It is recommended that models be tested by careful consideration of PTFs and orienting the soil parameterization more towards representing a plausible hydrological behavior rather than focusing on matching the calibration data.
7
Ross, Peter J. "A method of deriving soil hydraulic properties from field water contents for application in water balance studies." Journal of Hydrology 144, no. 1-4 (April 1993): 143–53. http://dx.doi.org/10.1016/0022-1694(93)90169-a.
Full text
8
Hartmann, Anne, Markus Weiler, and Theresa Blume. "The impact of landscape evolution on soil physics: evolution of soil physical and hydraulic properties along two chronosequences of proglacial moraines." Earth System Science Data 12, no. 4 (December 4, 2020): 3189–204. http://dx.doi.org/10.5194/essd-12-3189-2020.
Full textAbstract:
Abstract. Soil physical properties highly influence soil hydraulic properties, which define the soil hydraulic behavior. Thus, changes within these properties affect water flow paths and the soil water and matter balance. Most often these soil physical properties are assumed to be constant in time, and little is known about their natural evolution. Therefore, we studied the evolution of physical and hydraulic soil properties along two soil chronosequences in proglacial forefields in the Central Alps, Switzerland: one soil chronosequence developed on silicate and the other on calcareous parent material. Each soil chronosequence consisted of four moraines with the ages of 30, 160, 3000, and 10 000 years at the silicate forefield and 110, 160, 4900, and 13 500 years at the calcareous forefield. We investigated bulk density, porosity, loss on ignition, and hydraulic properties in the form of retention curves and hydraulic conductivity curves as well as the content of clay, silt, sand, and gravel. Samples were taken at three depths (10, 30, 50 cm) at six sampling sites at each moraine. Soil physical and hydraulic properties changed considerably over the chronosequence. Particle size distribution showed a pronounced reduction in sand content and an increase in silt and clay content over time at both sites. Bulk density decreased, and porosity increased during the first 10 millennia of soil development. The trend was equally present at both parent materials, but the reduction in sand and increase in silt content were more pronounced at the calcareous site. The organic matter content increased, which was especially pronounced in the topsoil at the silicate site. With the change in physical soil properties and organic matter content, the hydraulic soil properties changed from fast-draining coarse-textured soils to slow-draining soils with high water-holding capacity, which was also more pronounced in the topsoil at the silicate site. The data set presented in this paper is available at the online repository of the German Research Center for Geosciences (GFZ; Hartmann et al., 2020b). The data set can be accessed via the DOI https://doi.org/10.5880/GFZ.4.4.2020.004.
9
Filipović, Vilim, Thomas Weninger, Lana Filipović, Andreas Schwen, Keith L. Bristow, Sophie Zechmeister-Boltenstern, and Sonja Leitner. "Inverse estimation of soil hydraulic properties and water repellency following artificially induced drought stress." Journal of Hydrology and Hydromechanics 66, no. 2 (June 1, 2018): 170–80. http://dx.doi.org/10.2478/johh-2018-0002.
Full textAbstract:
AbstractGlobal climate change is projected to continue and result in prolonged and more intense droughts, which can increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, withR2and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (Ks) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.
10
Alam, M. Shahabul, S. Lee Barbour, and Mingbin Huang. "Characterizing uncertainty in the hydraulic parameters of oil sands mine reclamation covers and its influence on water balance predictions." Hydrology and Earth System Sciences 24, no. 2 (February 18, 2020): 735–59. http://dx.doi.org/10.5194/hess-24-735-2020.
Full textAbstract:
Abstract. One technique to evaluate the performance of oil sands reclamation covers is through the simulation of long-term water balance using calibrated soil–vegetation–atmosphere transfer models. Conventional practice has been to derive a single set of optimized hydraulic parameters through inverse modelling (IM) based on short-term (<5–10 years) monitoring datasets. This approach is unable to characterize the impact of variability in the cover properties. This study utilizes IM to optimize the hydraulic properties for 12 soil cover designs, replicated in triplicate, at Syncrude's Aurora North mine site. The hydraulic parameters for three soil types (peat cover soil, coarse-textured subsoil, and lean oil sand substrate) were optimized at each monitoring site from 2013 to 2016. The resulting 155 optimized parameter values were used to define distributions for each parameter/soil type, while the progressive Latin hypercube sampling (PLHS) method was used to sample parameter values randomly from the optimized parameter distributions. Water balance models with the sampled parameter sets were used to evaluate variations in the maximum sustainable leaf area index (LAI) for five illustrative covers and quantify uncertainty associated with long-term water balance components and LAI values. Overall, the PLHS method was able to better capture broader variability in the water balance components than a discrete interval sampling method. The results also highlight that climate variability dominates the simulated variability in actual evapotranspiration and that climate and parameter uncertainty have a similar influence on the variability in net percolation.
11
Weninger, Thomas, Gernot Bodner, Janis Kreiselmeier, Parvathy Chandrasekhar, Stefan Julich, Karl-Heinz Feger, Kai Schwärzel, and Andreas Schwen. "Combination of Measurement Methods for a Wide-Range Description of Hydraulic Soil Properties." Water 10, no. 8 (August 2, 2018): 1021. http://dx.doi.org/10.3390/w10081021.
Full textAbstract:
Established measurement methods for hydraulic soil properties cover a limited soil moisture range. Simulations of soil water dynamics based on such observations are therefore rarely representative for all conditions from saturation to drought. Recent technical developments facilitate efficient and cheap collecting of soil water characteristics data, but the quantitative benefit of extended measurement campaigns has not been adequately tested yet. In this study, a combination of four methods to measure water retention and hydraulic conductivity at different moisture ranges was applied. Evaporation method, dewpoint psychrometry, hood infiltrometer experiments, and falling head method for saturated conductivity were conducted at two experimental sites in eastern Austria. Effects of including the particular methods in the measurement strategy were examined by visual evaluation and a 1D-modelling sensitivity study including drainage, infiltration and drought conditions. The evaporation method was considered essential due to its broad measurement range both for water retention and hydraulic conductivity. In addition to that, the highest effect on simulated water balance components was induced by the inclusion of separate conductivity measurements near saturation. Water content after three days of drainage was 15 percent higher and the transpiration rate in a drought period was 22 percent higher without near-saturated conductivity measurements. Based on relative comparisons between different combinations, we suggested combining evaporation method and hood infiltrometer experiments as the basis for representative predictions of soil water dynamics.
12
Benson, C. H., A. Sawangsuriya, B. Trzebiatowski, and W. H. Albright. "Postconstruction Changes in the Hydraulic Properties of Water Balance Cover Soils." Journal of Geotechnical and Geoenvironmental Engineering 133, no. 4 (April 2007): 349–59. http://dx.doi.org/10.1061/(asce)1090-0241(2007)133:4(349).
Full text
13
Ma, Liwang, Gerrit Hoogenboom, S. A. Saseendran, P. N. S. Bartling, Lajpat R. Ahuja, and Timothy R. Green. "Effects of Estimating Soil Hydraulic Properties and Root Growth Factor on Soil Water Balance and Crop Production." Agronomy Journal 101, no. 3 (May 2009): 572–83. http://dx.doi.org/10.2134/agronj2008.0206x.
Full text
14
Ramos, T. B., M. C. Gonçalves, D. Brito, J. C. Martins, and L. S. Pereira. "Development of class pedotransfer functions for integrating water retention properties into Portuguese soil maps." Soil Research 51, no. 4 (2013): 262. http://dx.doi.org/10.1071/sr12347.
Full textAbstract:
Hydrological modellers have recently been challenged to improve watershed models by better integrating soil information into model applications. Reliable soil hydraulic information is thus necessary for better describing the water balance components at the catchment scale. Frequently, that information does not exist. This study presents a set of class-pedotransfer functions (PTFs) for estimating the water retention properties of Portuguese soils. The class-PTFs were established from a dataset containing 697 soil horizons/layers, by averaging values of total porosity and volumetric water contents at –0.25, –1, –3.2, –6.3, –10, –33, –100, –250, and –1500 kPa matric potentials after grouping data by soil texture class, soil horizon, and bulk density. Fitted retention curves using the van Genuchten model were also obtained for every class-PTF. The root mean square error varied between 0.039 and 0.057 cm3/cm3, with smaller values found when using the 12 texture classes of the International Soil Science Society (ISSS) system rather than the five texture classes of FAO, and when bulk density was also considered. The class-PTFs were then integrated into Portuguese soil maps and its usage was demonstrated by deriving maps of available water capacity to be used for modelling the water balance in a small catchment area with the SWAT model. The model successfully simulated the reservoir inflow when using the derived maps, but the results did not vary much whether using coarser or finer description of the catchment soils. Nonetheless, the class-PTFs contributed to a better soil characterisation than when using coarse-scaled information. The approach followed here was simple, inexpensive, and feasible for modellers with few resources but interested in considering the spatial variability of soil retention properties at large scales and in advancing hydrologic modelling in Portugal.
15
Dionizio, Emily, and Marcos Costa. "Influence of Land Use and Land Cover on Hydraulic and Physical Soil Properties at the Cerrado Agricultural Frontier." Agriculture 9, no. 1 (January 21, 2019): 24. http://dx.doi.org/10.3390/agriculture9010024.
Full textAbstract:
Western Bahia is one of the most active agricultural frontiers in the world, which raises concern about its natural resources conservation, especially regarding water availability. This study evaluated the influence of five different land uses and land covers on physical and hydraulic soil properties, and developed pedotransfer functions to derive regional hydraulic properties. Significant changes between physical and hydraulic soil properties under agricultural areas and under natural vegetation cover were found, reinforcing that agricultural activity may influence the soil water balance. Cerrado and Forest formation areas have higher infiltration rates ( K s a t ) compared to managed areas, with average values of 16.29 cm h−1, and 14.47 cm h−1, while irrigated croplands, rainfed croplands and pasture areas have much smaller infiltration rates, with K s a t equal to 3.01 cm h−1, 6.22 cm h−1 and 5.01 cm h−1, respectively. Our results suggest that the agriculture practices do not directly affect the vertical nature of hydrological flowpath, except in the case of intensive irrigated agriculture areas, where K s a t reduction can lead to erosive processes favoring organic matter losses, and decreases in productivity and soil quality. Impacts of land use change on hydraulic and physical soil properties are a reality in the Cerrado agriculture frontier and there is an urgent need to monitor how these changes occur over time to develop effective mitigation strategies of soil and water conservation.
16
D'Urso, G., and A. Basile. "Physico-empirical approach for mapping soil hydraulic behaviour." Hydrology and Earth System Sciences 1, no. 4 (December 31, 1997): 915–23. http://dx.doi.org/10.5194/hess-1-915-1997.
Full textAbstract:
Abstract. Abstract: Pedo-transfer functions are largely used in soil hydraulic characterisation of large areas. The use of physico-empirical approaches for the derivation of soil hydraulic parameters from disturbed samples data can be greatly enhanced if a characterisation performed on undisturbed cores of the same type of soil is available. In this study, an experimental procedure for deriving maps of soil hydraulic behaviour is discussed with reference to its application in an irrigation district (30 km2) in southern Italy. The main steps of the proposed procedure are: i) the precise identification of soil hydraulic functions from undisturbed sampling of main horizons in representative profiles for each soil map unit; ii) the determination of pore-size distribution curves from larger disturbed sampling data sets within the same soil map unit. iii) the calibration of physical-empirical methods for retrieving soil hydraulic parameters from particle-size data and undisturbed soil sample analysis; iv) the definition of functional hydraulic properties from water balance output; and v) the delimitation of soil hydraulic map units based on functional properties.
17
Schneider, Sébastien, Diederik Jacques, and Dirk Mallants. "Inverse modelling with a genetic algorithm to derive hydraulic properties of a multi-layered forest soil." Soil Research 51, no. 5 (2013): 372. http://dx.doi.org/10.1071/sr13144.
Full textAbstract:
Modelling complex vadose-zone hydrological processes across a range of spatial scales requires models and hydraulic properties commensurate with the scale of investigation. This study investigates the ability of two conceptual models with contrasting complexity and parameter requirements to quantify accurately the one-dimensional water balance in a soil–vegetation–atmosphere (SVA) system. The two models tested were: (i) the mechanistic HYDRUS-1D model, which numerically solves the Richards equation for saturated–unsaturated water flow; and (ii) a compartment or budget model that includes simplified schemes for redistribution of water in the soil. We discuss model performance for parameter sets obtained by inverse modelling for an SVA system developed in a podzol soil with Scots pine vegetation in Belgium. Soil hydraulic properties were derived from field-based soil water content data collected at multiple depths in two lysimeters installed in the multi-layered forest soil and subject to atmospheric boundary conditions during nearly one full hydrological year. Parameter optimisation was based on a genetic algorithm including elitism as an operator for improving the search for optimal solutions with better performance scores. Four scenarios were developed to investigate (i) the impact of the type of conceptual flow model (mechanistic or compartment), and (ii) the effect of the degree of detail or granularity used to describe the soil profile, on the accuracy of inverse modelling (i.e. five or two material layers with different hydraulic properties or a homogeneous profile with effective properties). Results showed that for models with the same number of material layers as the number of pedogenic horizons in the soil profile, both conceptual models reasonably match the observed water contents at all depths. The mechanistic model implemented in HYDRUS-1D was the more accurate with root mean-square error (RMSE) values for water content based on all data ~0.02 cm3 cm–3, whereas for the compartment model the RMSE was ~0.03 cm3 cm–3. The results further illustrated that for a mildly heterogeneous soil (in terms of coefficient of variation for estimated hydraulic properties between soil horizons), the five-layer soil profile could be replaced by a single set of effective hydraulic properties with only a 35% reduction in performance compared with the five-layer mechanistic model. A functional evaluation of model performance using the cumulative annual drainage revealed overall good performance of the simplified models; drainage values calculated with the five-layer compartment model and the one- and two-layer mechanistic model were never more than 36% larger than their reference value. Global inverse parameter optimisation routines such as the genetic algorithm applied here are powerful tools to determine field-scale hydraulic properties of heterogeneous soil profiles for simple and complex models; model and parameter complexity can be customised depending on data availability and computational constraints.
18
Abaker, Wafa E., Frank Berninger, and Mike Starr. "Changes in soil hydraulic properties, soil moisture and water balance in Acacia senegal plantations of varying age in Sudan." Journal of Arid Environments 150 (March 2018): 42–53. http://dx.doi.org/10.1016/j.jaridenv.2017.12.004.
Full text
19
Iradukunda, Parfait, and Maurice O. Nyadawa. "Impact of Sedimentation on Water Seepage Capacity in Lake Nakuru, Kenya." Applied and Environmental Soil Science 2021 (February 16, 2021): 1–10. http://dx.doi.org/10.1155/2021/8889189.
Full textAbstract:
Accumulation and deposition of sediments in waterbody affect the seepage capacity that could lead to improper water balance and results in the water level rise. This study analysed the influence of sedimentation on seepage capacity in Lake Nakuru and the impact of sediment characteristics to the water seepage and the flow rate formation at the lake bed level. The study was performed by sampling and analysing the sediment cores from two locations in the lake. The sediment hydraulic properties, i.e., moisture and porosity, particle sizes, and hydraulic conductivity, were determined using the oven-drying method, sieve analysis, hydrometer analysis, and falling head tests, respectively. The results showed that the lake sediment sample from location P1 had an average ratio of 39.38% for silty soil, 34.00% for clayey sediment, and 26.63% for fine-sand sediment particles with the maximum permeability coefficient of 3.37 ∗ 10 − 5 cm/s, while the one from location P2 had an average ratio of 63.17% for sand, 20.17% for fine particles, and 16.67% for gravels with the maximum permeability coefficient of 0.010793 cm/s. The hydraulic conductivity of sediment sample from location P1 and P2 increased along the core depth. This could lead to the rise of water level due to the decreases of water movement induced from the sediment cementation in the top layers under the waterbody. Sedimentation affects Lake Nakuru water volume and water balance; hence, there is a need to control the inflow of sediment resulting from anthropogenic activities in the watershed.
20
Vaze, Jai, Brian R. Jenkins, Jin Teng, and Narendra K. Tuteja. "Soils fieldwork, analysis, and interpretation to support hydraulic and hydrodynamic modelling in the Murray floodplains." Soil Research 48, no. 4 (2010): 295. http://dx.doi.org/10.1071/sr09195.
Full textAbstract:
There are limited datasets which cover the heavy clays found in the Murray floodplain area. To understand the processes associated with the water balance within the Koondrook–Perricoota Forest (KPF), detailed hydraulic and hydrodynamic modelling of the flood inundation patterns and overland flow in the KPF is required. Reliable and accurate soils information is critical for any credible hydrologic or hydrodynamic modelling results. Extensive fieldwork across the entire KPF and detailed laboratory testing of the collected samples was undertaken to produce soils information including: spatial distribution of soil types, soil stratigraphy along the surface and subsurface flowpaths, soil hydraulic properties, soil salinity, and soil organic matter. Soil sampling and soil profile descriptions were undertaken at 26 sites spread across the forest. Deep drilling was done at 12 sites to check the existence of ancestral streams and for salinity profiles; soil hydrology testing to estimate infiltration rates was undertaken at 10 sites. Rapid appraisal methods for soil infiltration were developed for the project. Results were compared to soil pedotransfer functions generated from laboratory results; soil indexes including the dispersibilty index and electrochemical stability index; and typical infiltration and permeability rates inferred from soil texture and structure. The results from this study and the archived soil physical and hydraulic datasets can be used for any detailed hydraulic or hydrodynamic modelling exercise in the Murray floodplain area with similar soil properties.
21
Greene, RSB. "Soil physical properties of three geomorphic zones in a semiarid mulga woodland." Soil Research 30, no. 1 (1992): 55. http://dx.doi.org/10.1071/sr9920055.
Full textAbstract:
Soil physical properties were measured in three contiguous geomorphic zones of a patterned sequence of alternating groves and intergroves in a semi-arid mulga (Acacia aneura) woodland : (1) a runoff zone of stony, severely sealed, surface soil, (2) an interception zone at the bottom of the runoff zone, and adjoining (3) a runon zone of mulga groves. Infiltration was measured in the field under unsaturated and saturated conditions using a disc permeameter at water supply potentials of -40 and +10 mm respectively. Under unsaturated flow conditions, there were no significant differences in the sorptivity, three-dimensional infiltration rate and hydraulic conductivity between the three zones. However, under saturated flow conditions, the soils in the mulga groves had infiltration rates 5-10 times higher than the soils in the runoff and interception zones. This difference was explained by the presence of stable macropores >0.75 mm diameter in the mulga grove soils. Surface soil (0-10 mm) aggregates from mulga groves were also particularly stable to rapid wetting, measured by wet-sieving. Volumetric water contents (measured over a range of matric potentials from 0 to -5.0 kPa) of the 0-50 mm layer of soil from the mulga grove and interception zone were significantly (P = 0.05) higher than the 0-50 mm layer from the runoff zone. Micromorphological and scanning electron microscope (SEM) examination indicated that the total porosity of the soil surface from the mulga groves and interception zones was greater than that of the runoff zones. Measurement of soil-water content following a major rainfall event indicated that water had flowed off the runoff zones and accumulated in the mulga groves. These findings are consistent with the higher herbage production and biotic activity that is found to occur in the mulga grove and interception zone compared with the runoff zone following adequate rainfall. They also reveal part of the delicate balance of runoff redistribution in grove/intergrove areas and the potential for management to alter this balance.
22
Moreira, Virnei Silva, Luiz Antonio Candido, Debora Regina Roberti, Geovane Webler, Marcelo Bortoluzzi Diaz, Luis Gustavo Gonçalves de Gonçalves, Raphael Pousa, and Gervásio Annes Degrazia. "Influence of Soil Properties in Different Management Systems: Estimating Soybean Water Changes in the Agro-IBIS Model." Earth Interactions 22, no. 4 (March 1, 2018): 1–19. http://dx.doi.org/10.1175/ei-d-16-0033.1.
Full textAbstract:
Abstract The water balance in agricultural cropping systems is dependent on the physical and hydraulic characteristics of the soil and the type of farming, both of which are sensitive to the soil management. Most models that describe the interaction between the surface and the atmosphere do not efficiently represent the physical differences across different soil management areas. In this study, the authors analyzed the dynamics of the water exchange in the agricultural version of the Integrated Biosphere Simulator (IBIS) model (Agro-IBIS) in the presence of different physical soil properties because of the different long-term soil management systems. The experimental soil properties were obtained from two management systems, no tillage (NT) and conventional tillage (CT) in a long-term experiment in southern Brazil in the soybean growing season of 2009/10. To simulate NT management, this study modified the top soil layer in the model to represent the residual layer. Moreover, a mathematical adjustment to the computation of leaf area index (LAI) is suggested to obtain a better representation of the grain fill to the physiological maturity period. The water exchange dynamics simulated using Agro-IBIS were compared against experimental data collected from both tillage systems. The results show that the model well represented the water dynamics in the soil and the evapotranspiration (ET) in both management systems, in particular during the wet periods. Better results were found for the conventional tillage management system for the water balance. However, with the incorporation of a residual layer and soil properties in NT, the model improved the estimation of evapotranspiration by 6%. The ability of the Agro-IBIS model to estimate ET indicates its potential application in future climate scenarios.
23
Csorba, Szilveszter, Andrea Raveloson, Eszter Tóth, Viliam Nagy, and Csilla Farkas. "Modelling soil water content variations under drought stress on soil column cropped with winter wheat." Journal of Hydrology and Hydromechanics 62, no. 4 (December 1, 2014): 269–76. http://dx.doi.org/10.2478/johh-2014-0036.
Full textAbstract:
Abstract Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS), while three were kept under drought-stressed conditions (S). The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET), potential evaporation (PE) and total amount of water (TSW) in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S) for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from -1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structuredependent soil properties.
24
Basile, Angelo, Antonello Bonfante, Antonio Coppola, Roberto De Mascellis, Salvatore Falanga Bolognesi, Fabio Terribile, and Piero Manna. "How does PTF Interpret Soil Heterogeneity? A Stochastic Approach Applied to a Case Study on Maize in Northern Italy." Water 11, no. 2 (February 5, 2019): 275. http://dx.doi.org/10.3390/w11020275.
Full textAbstract:
Soil water balance on a local scale is generally achieved by applying the classical nonlinear Richards equation that requires hydraulic properties, namely, water retention and hydraulic conductivity functions, to be known. Its application in agricultural systems on field or larger scales involves three major problems being solved, related to (i) the assessment of spatial variability of soil hydraulic properties, (ii) accounting for this spatial variability in modelling large-scale soil water flow, and (iii) measuring the effects of such variability on real field variables (e.g., soil water storage, biomass, etc.). To deal with the first issue, soil hydraulic characterization is frequently performed by using the so-called pedotransfer functions (PTFs), whose effectiveness in providing the actual information on spatial variability has been questioned. With regard to the second problem, the variability of hydraulic properties at the field scale has often been dealt with using a relatively simple approach of considering soils in the field as an ensemble of parallel and statistically independent tubes, assuming only vertical flow. This approach in dealing with spatial variability has been popular in the framework of a Monte Carlo technique. As for the last issue, remote sensing seems to be the only viable solution to verify the pattern of variability, going by several modelling outputs which have considered the soil spatial variability. Based on these premises, the goals of this work concerning the issues discussed above are the following: (1) analyzing the sensitivity of a Richards-based model to the measured variability of θ(h) and k(θ) parameters; (2) establishing the predictive capability of PTF in terms of a simple comparison with measured data; and (3) establishing the effectiveness of use of PTF by employing as data quality control an independent and spatially distributed estimation of the Above Ground Biomass (AGB). The study area of approximately 2000 hectares mainly devoted to maize forage cultivation is located in the Po plain (Lodi), in northern Italy. Sample sites throughout the study area were identified for hydropedological analysis (texture, bulk density, organic matter content, and other chemical properties on all the samples, and water retention curve and saturated hydraulic conductivity on a sub-set). Several pedotransfer functions were tested; the PTF‒Vereckeen proved to be the best one to derive hydraulic properties of the entire soil database. The Monte Carlo approach was used to analyze model sensitivity to two measured input parameters: the slope of water retention curve (n) and the saturated hydraulic conductivity (k0). The analysis showed sensitivity of the simulated process to the parameter n being significantly higher than to k0, although the former was much less variable. The PTFs showed a smoothing effect of the output variability, even though they were previously validated on a set of measured data. Interesting positive and significant correlations were found between the n parameter, from measured water retention curves, and the NDVI (Normalized Difference Vegetation Index), when using multi-temporal (2004–2018) high resolution remotely sensed data on maize cultivation. No correlation was detected when the n parameter derived from PTF was used. These results from our case study mainly suggest that: (i) despite the good performance of PTFs calculated via error indexes, their use in the simulation of hydrological processes should be carefully evaluated for real field-scale applications; and (ii) the NDVI index may be used successfully as a proxy to evaluate PTF reliability in the field.
25
Soet, M., R. J. Ronda, J. N. M. Stricker, and A. J. Dolman. "Land surface scheme conceptualisation and parameter values for three sites with contrasting soils and climate." Hydrology and Earth System Sciences 4, no. 2 (June 30, 2000): 283–94. http://dx.doi.org/10.5194/hess-4-283-2000.
Full textAbstract:
Abstract. The objective of the present study is to test the performance of the ECMWF land surface module (LSM) developed by Viterbo and Beljaars (1995) and to identify primary future adjustments, focusing on the hydrological components. This was achieved by comparing off-line simulations against observations and a detailed state-of-the-art model over a range of experimental conditions. Results showed that the standard LSM, which uses fixed vegetation and soil parameter values, systematically underestimated evapotranspiration, partly due to underestimating bare soil evaporation, which appeared to be a conceptual problem. In dry summer conditions, transpiration was seriously underestimated. The bias in surface runoff and percolation was not of the same sign for all three locations. A sensitivity analysis, set up to explore the impact of using standard parameter values, found that implementing specific soil hydraulic properties had a significant effect on runoff and percolation at all three sites. Evapotranspiration, however affected only slightly at the temperate humid climate sites. Under semi-arid conditions, introducing site specific soil hydraulic properties plus a realistic rooting depth improved simulation results considerably. Future adjustments to the standard LSM should focus on parameter values of soil hydraulic functions and rooting depths and, conceptually, on the bare soil evaporation parameterisation and the soil bottom boundary condition. Implications of changing soil hydraulic properties for future large-simulations were explored briefly. For Europe, soil data requirements can be fulfilled partly by the recent data base HYPRES. Sandy and loamy sand soils will then cover about 65% of Europe, whereas in the present model 100% of the area is loam. Keywords: land surface model; soil hydraulic properties; water balance simulation
26
Connolly, R. D., D. M. Freebairn, M. J. Bell, and G. Thomas. "Effects of rundown in soil hydraulic condition on crop productivity in south-eastern Queensland - a simulation study." Soil Research 39, no. 5 (2001): 1111. http://dx.doi.org/10.1071/sr00089.
Full textAbstract:
Declining soil organic matter levels because of cropping have been shown to reduce crop growth and yield, but the effects of changing infiltration and soil hydraulic properties on crop productivity have not been widely evaluated. Cropping systems in south-eastern Queensland have, in the past, involved intense tillage, trafficking with heavy machinery, and changed organic matter cycling, affecting soil aggregation, permeability, water-holding characteristics, and organic matter. The aim of this paper is to determine how important infiltration and soil hydraulic condition has been to the water balance, crop growth, and yield in the past, and may be in the future if management is not changed. Change in physical and chemical condition of the 5 most commonly cropped soils in south-east Queensland (Sodosols, Vertosols with ≤55% clay, Vertosols with >55% clay, Red Ferrosols and Red Chromosols/Kandosols) was measured over 0–70 years of cropping and estimated up to 200 years. The APSIM model was used to predict effects of changing soil condition in a rain-fed, fertilised, wheat-summer fallow cropping system with intense tillage. Decline in infiltration, restricted internal redistribution of water, and increased evaporation reduced water supply to the crop, causing simulated yield to decline by 29, 38, 25, 17, and 13% for the 5 soils, respectively, after 50 years of cropping. Gross margin declined at a faster rate, falling by 36, 50, 40, 20, and 21%, respectively after 50 years because of increasing fertiliser requirement to compensate for declining soil fertility. Crop productivity on most soils continued to steadily decline as period of cropping increased to 200 years. To arrest or reverse this downward trend, it is likely that substantial changes to current cropping systems will be needed, including reducing tillage and trafficking, and improving organic matter levels.
27
Li, Zhongkai, Hu Liu, Wenzhi Zhao, Qiyue Yang, Rong Yang, and Jintao Liu. "Quantification of soil water balance components based on continuous soil moisture measurement and the Richards equation in an irrigated agricultural field of a desert oasis." Hydrology and Earth System Sciences 23, no. 11 (November 18, 2019): 4685–706. http://dx.doi.org/10.5194/hess-23-4685-2019.
Full textAbstract:
Abstract. An accurate assessment of soil water balance components (SWBCs) is necessary for improving irrigation strategies in any water-limited environment. However, quantitative information on SWBCs is usually challenging to obtain, because none of the components (i.e., irrigation, drainage, and evapotranspiration) can be easily measured under actual conditions. Soil moisture is a variable that integrates the water balance components of land surface hydrology, and the evolution of soil moisture is assumed to contain the memory of antecedent hydrologic fluxes, and can thus be used to determine SWBCs from a hydrologic balance. A database of soil moisture measurements from six experimental plots with different treatments in the middle Heihe River basin of China was used to test the potential of a such a database for estimating SWBCs. We first compared the hydrophysical properties of the soils in these plots, such as vertical saturated hydraulic conductivity (Ks) and soil water retention features, for supporting SWBC estimations. We then determined evapotranspiration and other SWBCs using a method that combined the soil water balance method and the inverse Richards equation (a model of unsaturated soil water flow based on the Richards equation). To test the accuracy of our estimation, we used both indirect methods (such as power consumption of the pumping irrigation well and published SWBCs values at nearby sites) and the water balance equation technique to verify the estimated SWBCs values, all of which showed good reliability with respect to our estimation method. Finally, the uncertainties of the proposed methods were analyzed to evaluate the systematic error of the SWBC estimation and any restrictions regarding its application. The results showed significant variances among the film-mulched plots in both the cumulative irrigation volumes (652.1–867.3 mm) and deep drainages (170.7–364.7 mm). Moreover, the un-mulched plot had remarkably higher values in both cumulative irrigation volumes (1186.5 mm) and deep drainages (651.8 mm) compared with the mulched plots. Obvious correlation existed between the volume of irrigation and that of drained water. However, the ET demands for all of the plots behaved pretty much the same, with the cumulative ET values ranging between 489.1 and 561.9 mm for the different treatments in 2016, suggesting that the superfluous irrigation amounts had limited influence on the accumulated ET throughout the growing season due to the poor water-holding capacity of the sandy soil. This work confirmed that relatively reasonable estimations of the SWBCs in coarse-textured sandy soils can be derived by using soil moisture measurements; the proposed methods provided a reliable solution over the entire growing season and showed a great potential for identifying appropriate irrigation amounts and frequencies, and thus a move toward sustainable water resources management, even under traditional surface irrigation conditions.
28
Noguchi, Koichi, Hirotaka Saito, Reskiana Saefuddin, and Jiří Šimůnek. "Evaluation of Subsurface Drip Irrigation Designs in a Soil Profile with a Capillary Barrier." Water 13, no. 9 (May 6, 2021): 1300. http://dx.doi.org/10.3390/w13091300.
Full textAbstract:
Enhanced water use efficiency (WUE) is the key to sustainable agriculture in arid regions. The installation of capillary barriers (CB) has been suggested as one of the potential solutions. CB effects are observed between two soil layers with distinctly different soil hydraulic properties. A CB helps retain water in the upper, relatively fine-textured soil layer, suppressing water losses by deep drainage. However, retaining water in a shallow surface layer also intensifies water loss by evaporation. The use of subsurface drip irrigation (SDI) with a CB may prevent such water loss. This study evaluated the performance of SDI in a soil profile with a CB using a pot experiment and numerical analysis with the HYDRUS (2D/3D) software package. The ring-shaped emitter was selected for the SDI system for its low capital expenditures (CapEx) and maintenance. Strawberry was selected as a model plant. The results indicated that the proposed SDI system with a CB was effective in terms of WUE. The numerical analysis revealed that the CB’s depth influences the system’s water balance more than the ring-shaped emitter’s installation depth. While the CB’s shallow installation led to more root water uptake by the strawberry and less water loss by deep drainage, it induced more water loss by evaporation.
29
Chandrasekhar, Parvathy, Janis Kreiselmeier, Andreas Schwen, Thomas Weninger, Stefan Julich, Karl-Heinz Feger, and Kai Schwärzel. "Why We Should Include Soil Structural Dynamics of Agricultural Soils in Hydrological Models." Water 10, no. 12 (December 15, 2018): 1862. http://dx.doi.org/10.3390/w10121862.
Full textAbstract:
Surface soil structure is sensitive to natural and anthropogenic impacts that alter soil hydraulic properties (SHP). These alterations have distinct consequences on the water cycle. In this review, we summarized published findings on the quantitative effects of different agricultural management practices on SHP and the subsequent response of the water balance components. Generally, immediately after tillage, soils show a high abundance of large pores, which are temporally unstable and collapse due to environmental factors like rainfall. Nevertheless, most hydrological modeling studies consider SHP as temporally constant when predicting the flow of water and solutes in the atmosphere-plant-soil system. There have been some developments in mathematical approaches to capture the temporal dynamics of soil pore space. We applied one such pore evolution model to two datasets to evaluate its suitability to predict soil pore space dynamics after disturbance. Lack of knowledge on how dispersion of pore size distribution behaves after tillage may have led to over-estimation of some values predicted by the model. Nevertheless, we found that the model predicted the evolution of soil pore space reasonably well (r2 > 0.80 in most cases). The limiting factor to efficiently calibrate and apply such modeling tools is not in the theoretical part but rather the lack of adequate soil structural and hydrologic data.
30
Salas-García, J., J. Garfias, R. Martel, and L. Bibiano-Cruz. "A Low-Cost Automated Test Column to Estimate Soil Hydraulic Characteristics in Unsaturated Porous Media." Geofluids 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/6942736.
Full textAbstract:
The estimation of soil hydraulic properties in the vadose zone has some issues, such as accuracy, acquisition time, and cost. In this study, an inexpensive automated test column (ATC) was developed to characterize water flow in a homogeneous unsaturated porous medium by the simultaneous estimation of three hydraulic state variables: water content, matric potential, and water flow rates. The ATC includes five electrical resistance probes, two minitensiometers, and a drop counter, which were tested with infiltration tests using the Hydrus-1D model. The results show that calibrations of electrical resistance probes reasonably match with similar studies, and the maximum error of calibration of the tensiometers was 4.6% with respect to the full range. Data measured by the drop counter installed in the ATC exhibited a high consistency with the electrical resistance probes, which provides an independent verification of the model and indicates an evaluation of the water mass balance. The study results show good performance of the model against the infiltration tests, which suggests a robustness of the methodology developed in this study. An extension to the applicability of this system could be successfully used in low-budget projects in large-scale field experiments, which may be correlated with resistivity changes.
31
Soylu, M. E., E. Istanbulluoglu, J. D. Lenters, and T. Wang. "Quantifying the impact of groundwater depth on evapotranspiration in a semi-arid grassland region." Hydrology and Earth System Sciences 15, no. 3 (March 7, 2011): 787–806. http://dx.doi.org/10.5194/hess-15-787-2011.
Full textAbstract:
Abstract. Interactions between shallow groundwater and land surface processes play an important role in the ecohydrology of riparian zones. Some recent land surface models (LSMs) incorporate groundwater-land surface interactions using parameterizations at varying levels of detail. In this paper, we examine the sensitivity of land surface evapotranspiration (ET) to water table depth, soil texture, and two commonly used soil hydraulic parameter datasets using four models with varying levels of complexity. The selected models are Hydrus-1D, which solves the pressure-based Richards equation, the Integrated Biosphere Simulator (IBIS), which simulates interactions among multiple soil layers using a (water-content) variant of the Richards equation, and two forms of a steady-state capillary flux model coupled with a single-bucket soil moisture model. These models are first evaluated using field observations of climate, soil moisture, and groundwater levels at a semi-arid site in south-central Nebraska, USA. All four models are found to compare reasonably well with observations, particularly when the effects of groundwater are included. We then examine the sensitivity of modelled ET to water table depth for various model formulations, node spacings, and soil textures (using soil hydraulic parameter values from two different sources, namely Rawls and Clapp-Hornberger). The results indicate a strong influence of soil texture and water table depth on groundwater contributions to ET. Furthermore, differences in texture-specific, class-averaged soil parameters obtained from the two literature sources lead to large differences in the simulated depth and thickness of the "critical zone" (i.e., the zone within which variations in water table depth strongly impact surface ET). Depending on the depth-to-groundwater, this can also lead to large discrepancies in simulated ET (in some cases by more than a factor of two). When the Clapp-Hornberger soil parameter dataset is used, the critical zone becomes significantly deeper, and surface ET rates become much higher, resulting in a stronger influence of deep groundwater on the land surface energy and water balance. In general, we find that the simulated sensitivity of ET to the choice of soil hydraulic parameter dataset is greater than the sensitivity to soil texture defined within each dataset, or even to the choice of model formulation. Thus, our findings underscore the need for future modelling and field-based studies to improve the predictability of groundwater-land surface interactions in numerical models, particularly as it relates to the parameterization of soil hydraulic properties.
32
Sprenger, M., T. H. M. Volkmann, T. Blume, and M. Weiler. "Estimating flow and transport parameters in the unsaturated zone with pore water stable isotopes." Hydrology and Earth System Sciences Discussions 11, no. 10 (October 10, 2014): 11203–45. http://dx.doi.org/10.5194/hessd-11-11203-2014.
Full textAbstract:
Abstract. Determining the soil hydraulic properties is a prerequisite to physically model transient water flow and solute transport in the vadose zone. Estimating these properties by inverse modelling techniques has become more common within the last two decades. While these inverse approaches usually fit simulations to hydrometric data, we expanded the methodology by using independent information about the stable isotope composition of the soil pore water depth profile as a single or additional optimization target. To demonstrate the potential and limits of this approach, we compared the results of three inverse modelling strategies where the fitting targets were (a) pore water isotope concentrations, (b) a combination of pore water isotope concentrations and soil moisture time series, and (c) a two-step approach using first soil moisture data to determine water flow parameters and then the pore water stable isotope concentrations to estimate the solute transport parameters. The analyses were conducted at three study sites with different soil properties and vegetation. The transient unsaturated water flow was simulated by numerically solving the Richards equation with the finite-element code of Hydrus-1D. The transport of deuterium was simulated with the advection-dispersion equation, and the Hydrus code was modified to allow for deuterium loss during evaporation. The Mualem–van Genuchten and the longitudinal dispersivity parameters were determined for two major soil horizons at each site. The results show that approach (a) using only the pore water isotope content cannot substitute hydrometric information to derive parameter sets that reflect the observed soil moisture dynamics, but gives comparable results when the parameter space is constrained by pedotransfer functions. Approaches (b) and (c) using both, the isotope profiles and the soil moisture time series resulted in satisfying model performances and good parameter identifiability. However, approach (b) has the advantage that it considers the isotope data not only for the solute transport parameters, but also for water flow, and thus increases parameter realism. Approaches (b) and (c) both outcompeted simulations run with parameters derived from pedotransfer functions, which did not result in satisfying model efficiencies. Overall, parameters based on this new approach that includes isotope data lead to similar model performances regarding the water balance and soil moisture dynamics and better parameter identifiability than the conventional inverse model approaches limited to hydrometric fitting targets. If only data from isotope profiles in combination with textural information is available, the results are still satisfactory. This method has the additional advantage that it will not only allow us to estimate water balance and response times, but also site specific time variant transit times or solute breakthrough within the soil profile.
33
Radka Kodešová and Lukáš, Brodský. "Comparison of CGMS-WOFOST and HYDRUS-1D Simulation Results for One Cell of CGMS-GRID50." Soil and Water Research 1, No. 2 (January 7, 2013): 39–48. http://dx.doi.org/10.17221/6504-swr.
Full textAbstract:
CGMS (Crop Growth Monitoring System) developed by JRC is an integrated system to monitor crop behaviour and quantitative crop yield forecast that operates on a European scale. To simulate water balance in the root zone the simulation model CGMS-WOFOST (SUPIT & VAN DER GOOT 2003) is used that is based on water storage routing. This study was performed to assess a possible impact of simplifications of the water storage routing based model on simulated water regime in the soil profile. Results of CGMS-WOFOST are compared with results of a more precise Richards’ equation based model HYDRUS-1D (ŠIMŮNEK et al. 2005). 16 scenarios are simulated using HYDRUS-1D. Each scenario represents a single soil profile presented in the selected cell of GRID50 in the Czech Republic. Geometry of the soil profiles, material (texture) definition, root distributions, measured daily rainfall, calculated daily evaporation from the bare soil surface and transpiration of crop canopy were defined similarly to CGMS-WOFOST inputs according to the data stored in the SGDBE40 database. The soil hydraulic properties corresponding to each soil layer were defined using the class transfer rules (WÖSTEN et al. 1999). The bottom boundary conditions were defined either similarly to CGMS-WOFOST bottom boundary condition as a free drainage or as a constant water level 250 cm below the soil surface to demonstrate a ground water impact on the soil profile water balance. The relative soil moisture (RSM) in the root zone during the vegetation period was calculated to be compared with the similar output from CGMS. The RSM values obtained using HYDRUS-1D are higher than those obtained using CGMS-WOFOST mostly due to higher retention ability of HYDRUS-1D. The reasonably higher RSM values were obtained at the end of simulated period using the HYDRUS-1D for the constant water level 250 cm below the soil surface.
34
Loch, R. J., and D. N. Orange. "Changes in some properties of topsoil at Tarong Coal - Meandu Mine coalmine with time since rehabilitation." Soil Research 35, no. 4 (1997): 777. http://dx.doi.org/10.1071/s96059.
Full textAbstract:
Three sites were studied at the Meandu Mine, Tarong, where vegetation had been established for 2, 4, and 6 growing seasons. Topsoil (a grey sandy loam, developed on sandstone) had been spread over sandstone spoil at all sites, to a depth of approximately 200 mm. At each site, areas were studied where either (i) all vegetation had been removed and the soil was disturbed to destroy any macropores that had developed, then allowed to consolidate under rainfall, or (ii) vegetation was clipped and pores in the soil were left undisturbed and intact. This allowed separate assessment of soil pores associated with re-aggregation and of the frequency and importance of stable macropores formed by soil fauna and by plant roots. Disc permeameters were used to measure hydraulic conductivities at the soil surface, and organic carbon and aggregate size distributions at the soil surface following rainfall wetting were measured. For bare, consolidated soil, hydraulic conductivities indicated that development of pores in the topsoil had reached a maximum after 4 seasons. This was consistent with aggregate size distributions after rainfall wetting, which indicated little change between 4 and 6 seasons. Hydraulic conductivities of vegetated areas showed responses to both length of time under vegetation and to plant species. The results showed that measurements of soil structure and of infiltration parameters made when soil was spread and rehabilitation commenced will greatly underestimate the long-term hydraulic conductivity of minesoils. Where long-term runoff, water balance, and vegetation growth are being considered, it would be preferable to measure input parameters on areas of established vegetation (preferably after at least 4 seasons of plant growth).
35
Sprenger, M., T. H. M. Volkmann, T. Blume, and M. Weiler. "Estimating flow and transport parameters in the unsaturated zone with pore water stable isotopes." Hydrology and Earth System Sciences 19, no. 6 (June 3, 2015): 2617–35. http://dx.doi.org/10.5194/hess-19-2617-2015.
Full textAbstract:
Abstract. Determining the soil hydraulic properties is a prerequisite to physically model transient water flow and solute transport in the vadose zone. Estimating these properties by inverse modelling techniques has become more common within the last 2 decades. While these inverse approaches usually fit simulations to hydrometric data, we expanded the methodology by using independent information about the stable isotope composition of the soil pore water depth profile as a single or additional optimization target. To demonstrate the potential and limits of this approach, we compared the results of three inverse modelling strategies where the fitting targets were (a) pore water isotope concentrations, (b) a combination of pore water isotope concentrations and soil moisture time series, and (c) a two-step approach using first soil moisture data to determine water flow parameters and then the pore water stable isotope concentrations to estimate the solute transport parameters. The analyses were conducted at three study sites with different soil properties and vegetation. The transient unsaturated water flow was simulated by solving the Richards equation numerically with the finite-element code of HYDRUS-1D. The transport of deuterium was simulated with the advection-dispersion equation, and a modified version of HYDRUS was used, allowing deuterium loss during evaporation. The Mualem–van Genuchten and the longitudinal dispersivity parameters were determined for two major soil horizons at each site. The results show that approach (a), using only the pore water isotope content, cannot substitute hydrometric information to derive parameter sets that reflect the observed soil moisture dynamics but gives comparable results when the parameter space is constrained by pedotransfer functions. Approaches (b) and (c), using both the isotope profiles and the soil moisture time series, resulted in good simulation results with regard to the Kling–Gupta efficiency and good parameter identifiability. However, approach (b) has the advantage that it considers the isotope data not only for the solute transport parameters but also for water flow and root water uptake, and thus increases parameter realism. Approaches (b) and (c) both outcompeted simulations run with parameters derived from pedotransfer functions, which did not result in an acceptable representation of the soil moisture dynamics and pore water stable isotope composition. Overall, parameters based on this new approach that includes isotope data lead to similar model performances regarding the water balance and soil moisture dynamics and better parameter identifiability than the conventional inverse model approaches limited to hydrometric fitting targets. If only data from isotope profiles in combination with textural information is available, the results are still satisfactory. This method has the additional advantage that it will not only allow us to estimate water balance and response times but also site-specific time variant transit times or solute breakthrough within the soil profile.
36
Green, S. R., I. Vogeler, B. E. Clothier, T. M. Mills, and C. van den Dijssel. "Modelling water uptake by a mature apple tree." Soil Research 41, no. 3 (2003): 365. http://dx.doi.org/10.1071/sr02129.
Full textAbstract:
We report the results from a field experiment in which we examined the spatial and temporal patterns of water uptake by a mature apple tree (Malus domestica Borkh., 'Splendour') in an orchard. Time domain reflectometry was used to measure changes in the soil's volumetric water content, and heat-pulse was used to monitor locally the rates of sap flow in the trunk and roots of the tree. The tree's distribution of root-length density and supporting data to characterise the soil's hydraulic properties were determined for the purpose of modelling soil water movement in the root-zone under an apple tree. Experimental data are compared against the output from a numerical model of the soil water balance that uses Richards' equation for water flow, and uses a distributed macroscopic sink term for root uptake. In general, there was a very good agreement between the measured and modelled results. The apple trees consumed some 70 L of water per day during the middle of summer. The daily water use declined to about 20 L per day with the onset of autumn, coinciding with a reduced evaporative demand and an increasing number of rain days. Water movement in the root-zone soil was dominated by the water uptake via surface roots. Large changes in soil water content were also associated with each irrigation event. Our experimental data support the contention that more frequent irrigation in smaller doses will result in less water percolating through the root-zone. Such an irrigation strategy should make more efficient use of water by minimising the leaching losses. It will also be helpful for environmental protection by reducing the percolation losses of water and solute beyond the grasp of the roots.
37
David, Teresa Soares, Clara Assunção Pinto, Nadezhda Nadezhdina, and Jorge Soares David. "Water and forests in the Mediterranean hot climate zone: a review based on a hydraulic interpretation of tree functioning." Forest Systems 25, no. 2 (July 20, 2016): eR02. http://dx.doi.org/10.5424/fs/2016252-08899.
Full textAbstract:
Aim of the study: Water scarcity is the main limitation to forest growth and tree survival in the Mediterranean hot climate zone. This paper reviews literature on the relations between water and forests in the region, and their implications on forest and water resources management. The analysis is based on a hydraulic interpretation of tree functioning.Area of the study: The review covers research carried out in the Mediterranean hot climate zone, put into perspective of wider/global research on the subject. The scales of analysis range from the tree to catchment levels.Material and Methods: For literature review we used Scopus, Web of Science and Google Scholar as bibliographic databases. Data from two Quercus suber sites in Portugal were used for illustrative purposes.Main results: We identify knowledge gaps and discuss options to better adapt forest management to climate change under a tree water use/availability perspective. Forest management is also discussed within the wider context of catchment water balance: water is a constraint for biomass production, but also for other human activities such as urban supply, industry and irrigated agriculture.Research highlights: Given the scarce and variable (in space and in time) water availability in the region, further research is needed on: mapping the spatial heterogeneity of water availability to trees; adjustment of tree density to local conditions; silvicultural practices that do not damage soil properties or roots; irrigation of forest plantations in some specific areas; tree breeding. Also, a closer cooperation between forest and water managers is needed.Keywords: tree hydraulics; tree mortality; climate change; forest management; water resources.
38
Troch, P. A., G. Carrillo, M. Sivapalan, T. Wagener, and K. Sawicz. "Climate-vegetation-soil interactions and long-term hydrologic partitioning: signatures of catchment co-evolution." Hydrology and Earth System Sciences Discussions 10, no. 3 (March 7, 2013): 2927–54. http://dx.doi.org/10.5194/hessd-10-2927-2013.
Full textAbstract:
Abstract. Catchment hydrologic partitioning, regional vegetation composition and soil properties are strongly affected by climate, but the effects of climate-vegetation-soil interactions on river basin water balance are still poorly understood. Here we use a physically-based hydrologic model separately parameterized in 12 US catchments across a climate gradient to decouple the impact of climate and landscape properties to gain insight into the role of climate-vegetation-soil interactions in long-term hydrologic partitioning. The 12 catchment models (with different parameterizations) are subjected to the 12 different climate forcings, resulting in 144 10-yr model simulations. The results are analyzed per catchment (one catchment model subjected to 12 climates) and per climate (one climate filtered by 12 different model parameterization), and compared to water balance predictions based on Budyko's hypothesis (E/P = φ (EP/P); E: evaporation, P: precipitation, EP: potential evaporation). We find significant anti-correlation between average deviations of the evaporation index (E/P) computed per catchment vs. per climate, compared to that predicted by Budyko. Catchments that on average produce more E/P have developed in climates that on average produce less E/P, when compared to Budyko's prediction. Water and energy seasonality could not explain these observations, confirming previous results reported by Potter et al. (2005). Next, we analyze which model (i.e., landscape filter) characteristics explain the catchment's tendency to produce more or less E/P. We find that the time scale that controls perched aquifer storage release explains the observed trend. This time scale combines several geomorphologic and hydraulic soil properties. Catchments with relatively longer aquifer storage release time scales produce significantly more E/P. Vegetation in these catchments have longer access to this additional groundwater source and thus are less prone to water stress. Further analysis reveals that climates that give rise to more (less) E/P are associated with catchments that have vegetation with less (more) efficient water use parameters. In particular, the climates with tendency to produce more E/P have catchments that have lower % root fraction and less light use efficiency. Our results suggest that there exists strong interactions between climate, vegetation and soil properties that lead to specific hydrologic partitioning at the catchment scale. This co-evolution of catchment vegetation and soils with climate needs to be further explored to improve our capabilities to predict hydrologic partitioning in ungaged basins.
39
Prior, LD, AM Grieve, PG Slavich, and BR Cullis. "Sodium chloride and soil texture interactions in irrigated field grown sultana grapevines. III. Soil and root system effects." Australian Journal of Agricultural Research 43, no. 5 (1992): 1085. http://dx.doi.org/10.1071/ar9921085.
Full textAbstract:
Five salinity treatments, ranging between 0.37 and 3.47 dS m-1, were applied through a trickle irrigation system to own-rooted sultana grapevines for six years. The changes in soil salinity levels and the relationship between soil salinity and yield were studied, and a simplified salt balance model was developed to calculate leaching fractions. Soil salinity was strongly influenced by soil texture as well as by salt treatment, because leaching fractions were lower in heavier soils; they averaged 23% in the lightest soils and 10% in the heaviest. Leaching fractions also increased with salt treatment, from 7% in the 0.37 dS m-1 treatment to 24% in the 3.47 dS m-1 treatment. This was probably because water use by salinized vines was lower. Yield was correlated with mean soil salinity, ECe, but the relationship was not as good as with plant salinity levels. The fitted model accounted for between 52 and 62% of the variance. It was concluded that soil salinity levels at the end of winter should be maintained below 1.0 dS m-1 in order to keep yield losses below 10%. For own-rooted sultana grapevines in Sunraysia, this requires a leaching fraction of about 8%. Rootzone depth and root density were lower in the heavier soils, and were decreased by salt treatment. The deleterious effects of salt treatment on clay dispersion and soil hydraulic conductivity were also greater in the heavier soils. Soil properties must therefore be considered when predicting the effects of saline water on crop productivity, especially in the long term.
40
Cataldo, Eleonora, Linda Salvi, Francesca Paoli, Maddalena Fucile, Grazia Masciandaro, Davide Manzi, Cosimo Maria Masini, and Giovan Battista Mattii. "Application of Zeolites in Agriculture and Other Potential Uses: A Review." Agronomy 11, no. 8 (July 31, 2021): 1547. http://dx.doi.org/10.3390/agronomy11081547.
Full textAbstract:
Excessive use of nitrogen fertilizer and inappropriate fertilization designs have negative results in agricultural ecosystems, such as considerable nitrogen losses through nitrogen dioxide (NO2) soil leaching and ammonia NH3 volatilization. In addition, climate change, with rising summer temperatures and reduced precipitation, leads to production declines and water shortages in the soil. This review aims to highlight the characteristics of natural zeolite and focus on their multiple uses in agriculture. These minerals are tectosilicates showing an open three-dimensional structure involving the cations required to balance the framework electrostatic charge of aluminum and silicon tetrahedral units. Different research groups reported more than fifty natural zeolites; chabazite, clinoptilolite, phillipsite, erionite, stilbite, heulandite, and mordenite are the most well-known. Zeolites are great tools to help the farmer and agronomist cope with several issues, such as soil or water pollution, contamination by heavy metals, loss of nutrients, and loss of water-use efficiency (WUE) of drylands. These natural crystalline aluminosilicates are considered soil conditioners to improve soil chemical and physical properties, such as saturated hydraulic conductivity (Ks), infiltration rate, cation exchange capacity (CEC), and water-holding capacity (WHC). Owing to their properties, these materials are able to reduce nitrate leaching and ammonia volatilization. Zeolites are also known for their carrying capacity of slow-release macronutrients, micronutrients, and fertilizers. However, the potential of these materials in agricultural areas is apparent, and zeolites show the promise of contributing directly to improve agricultural ecosystems as a sustainable product.
41
Troch, P. A., G. Carrillo, M. Sivapalan, T. Wagener, and K. Sawicz. "Climate-vegetation-soil interactions and long-term hydrologic partitioning: signatures of catchment co-evolution." Hydrology and Earth System Sciences 17, no. 6 (June 18, 2013): 2209–17. http://dx.doi.org/10.5194/hess-17-2209-2013.
Full textAbstract:
Abstract. Budyko (1974) postulated that long-term catchment water balance is controlled to first order by the available water and energy. This leads to the interesting question of how do landscape characteristics (soils, geology, vegetation) and climate properties (precipitation, potential evaporation, number of wet and dry days) interact at the catchment scale to produce such a simple and predictable outcome of hydrological partitioning? Here we use a physically-based hydrologic model separately parameterized in 12 US catchments across a climate gradient to decouple the impact of climate and landscape properties to gain insight into the role of climate-vegetation-soil interactions in long-term hydrologic partitioning. The 12 catchment models (with different paramterizations) are subjected to the 12 different climate forcings, resulting in 144 10 yr model simulations. The results are analyzed per catchment (one catchment model subjected to 12 climates) and per climate (one climate filtered by 12 different model parameterization), and compared to water balance predictions based on Budyko's hypothesis (E/P = &varphi; (Ep/P); E: evaporation, P: precipitation, Ep: potential evaporation). We find significant anti-correlation between average deviations of the evaporation index (E/P) computed per catchment vs. per climate, compared to that predicted by Budyko. Catchments that on average produce more E/P have developed in climates that on average produce less E/P, when compared to Budyko's prediction. Water and energy seasonality could not explain these observations, confirming previous results reported by Potter et al. (2005). Next, we analyze which model (i.e., landscape filter) characteristics explain the catchment's tendency to produce more or less E/P. We find that the time scale that controls subsurface storage release explains the observed trend. This time scale combines several geomorphologic and hydraulic soil properties. Catchments with relatively longer subsurface storage release time scales produce significantly more E/P. Vegetation in these catchments have longer access to this additional groundwater source and thus are less prone to water stress. Further analysis reveals that climates that give rise to more (less) E/P are associated with catchments that have vegetation with less (more) efficient water use parameters. In particular, the climates with tendency to produce more E/P have catchments that have lower % root fraction and less light use efficiency. Our results suggest that their exists strong interactions between climate, vegetation and soil properties that lead to specific hydrologic partitioning at the catchment scale. This co-evolution of catchment vegetation and soils with climate needs to be further explored to improve our capabilities to predict hydrologic partitioning in ungauged basins.
42
Ma, Qingli, James E. Hook, and Laj R. Ahuja. "Influence of three-parameter conversion methods between van Genuchten and Brooks-Corey Functions on soil hydraulic properties and water-balance predictions." Water Resources Research 35, no. 8 (August 1999): 2571–78. http://dx.doi.org/10.1029/1999wr900096.
Full text
43
Ralaizafisoloarivony, Njaka, Aurore Degré, Benoit Mercatoris, Angélique Leonard, Dominique Toye, and Robert Charlier. "Assessing Soil Crack Dynamics and Water Evaporation during Dryings of Agricultural Soil from Reduced Tillage and Conventional Tillage Fields." Proceedings 30, no. 1 (May 19, 2020): 59. http://dx.doi.org/10.3390/proceedings2019030059.
Full textAbstract:
Crack formation and development have been a general concern in agricultural science. Cracks contribute to soil aeration, aggregate formation, and easy root penetration. However, cracks accelerate soil desiccation, allow deep infiltration of pesticides/pollutants through preferential flow, and pollute the shallow water table in Belgium. Cracks have mostly been studied in pure clay or in high-clay-content soil (Vertisol). Yet, in Wallonia, cracks were also present on silt–loam soil (Luvisol). This study tried to cover this gap by analysing crack dynamics and evaporation process, during drying kinetics of the Luvisol. Soils were collected directly from the agricultural field and processed on a small drying chamber in which an evaporation test took place. A ceramic IR emitter heated the chamber while sensors (DHT22) measured the temperature and relative humidity. A digital camera took photos of the soil surface at 30-min intervals. A balance and tensiometer were linked to a datalogger (CR800), and recorded the soil hydraulic properties (evaporation rate, etc.). Cracks were assessed from small samples (~5 cm × 1cm thick) and big samples (~20 cm size × 1.6 cm thick). Three treatments were considered, including disturbed soil, conventional tillage and reduced tillage. For big samples, results showed higher crack formation on disturbed soil > reduced tillage > conventional tillage, due to loose soil cohesion, soil organic content, soil aggregation, biological activities, and soil porosity. The soil evaporation rate was also greater in disturbed soil > reduced tillage > conventional tillage. Cracks opening exposed a large quantity of soil water to the atmosphere without it passing through the soil matrix. For small samples, the repetitive drying experiments increased cracks’ length and width, especially for the dense samples. The results indicated the presence of pre-existing (or micro-) cracks in the soil samples. Future study is needed to assess the presence of pre- (micro-) cracks in soil using X-ray microtomography.
44
Cresto Aleina, F., V. Brovkin, S. Muster, J. Boike, L. Kutzbach, T. Sachs, and S. Zuyev. "A stochastic model for the polygonal tundra based on Poisson–Voronoi diagrams." Earth System Dynamics 4, no. 2 (July 11, 2013): 187–98. http://dx.doi.org/10.5194/esd-4-187-2013.
Full textAbstract:
Abstract. Subgrid processes occur in various ecosystems and landscapes but, because of their small scale, they are not represented or poorly parameterized in climate models. These local heterogeneities are often important or even fundamental for energy and carbon balances. This is especially true for northern peatlands and in particular for the polygonal tundra, where methane emissions are strongly influenced by spatial soil heterogeneities. We present a stochastic model for the surface topography of polygonal tundra using Poisson–Voronoi diagrams and we compare the results with available recent field studies. We analyze seasonal dynamics of water table variations and the landscape response under different scenarios of precipitation income. We upscale methane fluxes by using a simple idealized model for methane emission. Hydraulic interconnectivities and large-scale drainage may also be investigated through percolation properties and thresholds in the Voronoi graph. The model captures the main statistical characteristics of the landscape topography, such as polygon area and surface properties as well as the water balance. This approach enables us to statistically relate large-scale properties of the system to the main small-scale processes within the single polygons.
45
Cresto Aleina, F., V. Brovkin, S. Muster, J. Boike, L. Kutzbach, T. Sachs, and S. Zuyev. "A stochastic model for the polygonal tundra based on Poisson-Voronoi Diagrams." Earth System Dynamics Discussions 3, no. 1 (June 29, 2012): 453–83. http://dx.doi.org/10.5194/esdd-3-453-2012.
Full textAbstract:
Abstract. Sub-grid processes occur in various ecosystems and landscapes but, because of their small scale, they are not represented or poorly parameterized in climate models. These local heterogeneities are often important or even fundamental for energy and carbon balances. This is especially true for northern peatlands and in particular for the polygonal tundra where methane emissions are strongly influenced by spatial soil heterogeneities. We present a stochastic model for the surface topography of polygonal tundra using Poisson-Voronoi Diagrams and we compare the results with available recent field studies. We analyze seasonal dynamics of water table variations and the landscape response under different scenarios of precipitation income. We upscale methane fluxes by using a simple idealized model for methane emission. Hydraulic interconnectivities and large-scale drainage may also be investigated through percolation properties and thresholds in the Voronoi graph. The model captures the main statistical characteristics of the landscape topography, such as polygon area and surface properties as well as the water balance. This approach enables us to statistically relate large-scale properties of the system taking into account the main small-scale processes within the single polygons.
46
Papafotiou, A., C. Schütz, P. Lehmann, P. Vontobel, D. Or, and I. Neuweiler. "MEASUREMENT OF PREFERENTIAL FLOW DURING INFILTRATION AND EVAPORATION IN POROUS MEDIA." Bulletin of the Geological Society of Greece 43, no. 4 (January 25, 2017): 1831. http://dx.doi.org/10.12681/bgsg.11374.
Full textAbstract:
Infiltration and evaporation are governing processes for water exchange between soil and atmosphere. In addition to atmospheric supply or demand, infiltration and evaporation rates are controlled by the material properties of the subsurface and the interplay between capillary, viscous and gravitational forces. This is commonly modeled with semi-empirical approaches using continuum models, such as the Richards equation for unsaturated flow. However, preferential flow phenomena often occur, limiting or even entirely suspending the applicability of continuum-based models. During infiltration, unstable fingers may form in homogeneous or heterogeneous porous media. On the other hand, the evaporation process may be driven by the hydraulic coupling of materials with different hydraulic functions found in heterogeneous systems. To analyze such preferential flow processes, water distribution was monitored in infiltration and evaporation lab experiments using neutron transmission techniques. Measurements were performed in 2D and 3D, using homogeneous and heterogeneous setups. The experimental findings demonstrate the fingering effect in infiltration and how it is influenced by the presence of fine inclusions in coarse background material. During evaporation processes, the hydraulic coupling effect is found to control the evaporation rate, limiting the modeling of water balances between soil and surface based on surface information alone.
47
Garrigues, S., A. Olioso, J. C. Calvet, E. Martin, S. Lafont, S. Moulin, A. Chanzy, et al. "Evaluation of land surface model simulations of evapotranspiration over a 12 year crop succession: impact of the soil hydraulic properties." Hydrology and Earth System Sciences Discussions 11, no. 10 (October 23, 2014): 11687–733. http://dx.doi.org/10.5194/hessd-11-11687-2014.
Full textAbstract:
Abstract. Evapotranspiration has been recognized as one of the most uncertain term in the surface water balance simulated by land surface models. In this study, the SURFEX/ISBA-A-gs simulations of evapotranspiration are assessed at local 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 dynamic of simulated and measured evapotranspiration over a long period of time. The analysis focuses on key soil parameters which drive the simulation of evapotranspiration, namely the rooting depth, the soil moisture at saturation, the soil moisture at field capacity and the soil moisture at wilting point. The simulations achieved with the standard values of these parameters are compared to those achieved with the in situ values. The portability of the ISBA pedotransfer functions is evaluated over a typical Mediterranean crop site. Various in situ estimates of the soil parameters are considered and distinct parametrization strategies are tested to represent the evapotranspiration dynamic over the crop succession. This work shows that evapotranspiration mainly results from the soil evaporation when it is continuously simulated over a Mediterranean 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 overestimation of the soil moisture at wilting point causes the underestimation of transpiration at the end of the crop cycles. The overestimation of the soil moisture at saturation triggers the underestimation of the soil evaporation during the wet soil periods. The use of field capacity values derived from laboratory retention measurements leads to inaccurate simulation of soil evaporation due to the lack of representativeness of the soil structure variability at the field scale. The most accurate simulation is achieved with the values of the soil hydraulic properties derived from field measured soil moisture. Their temporal analysis over each crop cycle provides meaningful estimates of the wilting point, the field capacity and the rooting depth to represent the crop water needs and accurately simulate the evapotranspiration over the crop succession. We showed that the uncertainties in the eddy-covariance measurements are significant and can explain a large part of the unresolved random differences between the simulations and the measurements of evapotranspiration. Other possible model shortcomings include the lack of representation of soil vertical heterogeneity and root profile along with inaccurate energy balance partitioning between the soil and the vegetation at low LAI.
48
Slavich, P. G., G. H. Petterson, and D. Griffin. "Effects of irrigation water salinity and sodicity on infiltration and lucerne growth over a shallow watertable." Australian Journal of Experimental Agriculture 42, no. 3 (2002): 281. http://dx.doi.org/10.1071/ea00124.
Full textAbstract:
Irrigation using saline sodic groundwater is a major strategy to manage salinisation from shallow watertables in the irrigation areas of south-east Australia. There is concern that this strategy will increase soil sodicity and induce a decline in soil physical properties that affect infiltration. Laboratory experiments have shown that the saturated hydraulic conductivity of soils may decrease when a saline–sodic soil is leached with low salinity water. This paper evaluates the field significance of these concerns to irrigation water management practices. The effects of changing the irrigation water source from saline–sodic groundwater to low salinity channel water on the infiltration properties of a hardsetting red-brown earth and the yield of lucerne (Medicago sativa) were evaluated over a 3-year period. Four dilution strategies to use high-salinity (EC 6 dS/m) and high-sodicity [SAR 16 (mmol/L)0.5] groundwater were compared. They were: (i) irrigation with groundwater in the spring then channel water for remainder of the summer irrigation season; (ii) irrigation with channel water in spring then groundwater for the rest of season; (iii) irrigation with diluted groundwater EC 3 dS/m for whole season; and (iv) alternative irrigations with groundwater EC 6 dS/m and channel water throughout the season. The control treatment was irrigated with low-salinity (EC 0.15 dS/m) channel water all season. The treatments were applied for 2 summer irrigation seasons then channel water was applied to all plots for another season. The site was underlain by a shallow watertable at 1.0 m. The final steady infiltration rate of each plot was measured each irrigation using capacitance water level loggers. This value was used as an index of soil structural stability to the water quality treatments. The results show all groundwater treatments caused the soil to increase in salinity from ECe(0–0.15 m) 0.6–0.9 dS/m to 3.8–7.3 dS/m and sodicity from SARe(0–0.15 m) 1.7–2.1 to 14.2–16.8 after 2 years of application. The steady infiltration rate was not affected by treatment during this period. In the third year when all plots were irrigated with channel water there was a small decrease in the steady infiltration rate during irrigation in the alternating groundwater treatment. The steady infiltration rates of the experimental soil were relatively low, varying from 4.9 to 7.0 mm/h for different water quality treatments. The most likely explanation of the small treatment effect is that infiltration in this soil is dominated by water entry via surface cracks. Soil analysis indicated that sufficient electrolyte was maintained in the matrix of the surface soil to prevent significant swelling and clay dispersion, even after many irrigations of channel water were applied. Water balance estimates and changes in profile salinity indicated that the lucerne used significant quantities of water directly from the watertable, concentrating salt within the capillary fringe above the watertable to a maximum of 36 dS/m. A larger proportion of the water requirement appeared to be taken up directly from the watertable where saline irrigation water was also applied. This led to rapid profile salinisation and sodification from a combination of upward flux from the watertable and salt applied in the irrigation water.
49
Ma, Qingli, James E. Hook, and Laj R. Ahuja. "Reply [to “Comment on ‘Influence of three-parameter conversion methods between van Genuchten and Brooks-Corey Functions on soil hydraulic properties and water-balance predictions’ by Qingli Ma et al.”]." Water Resources Research 37, no. 3 (March 2001): 853–55. http://dx.doi.org/10.1029/2000wr900347.
Full text
50
Pallas, Benoît, and Angélique Christophe. "Relationships between biomass allocation, axis organogenesis and organ expansion under shading and water deficit conditions in grapevine." Functional Plant Biology 42, no. 12 (2015): 1116. http://dx.doi.org/10.1071/fp15168.
Full textAbstract:
The relationships between whole-plant growth and morphogenetic processes under abiotic stresses are still partly unknown. Whole-plant biomass growth can be decreased by many abiotic stresses, including water deficit and shading. Two experiments were performed on potted plants of one grapevine cultivar (Vitis vinifera L. cv. Syrah) subjected to watering and shading treatments. Under water stress, plants reduced their primary and secondary axis leaf production rate, whereas secondary axis budburst was relatively unaffected. Individual leaf area was reduced and a strong decrease in leaf expansion rate was observed. Under shading, primary axis organogenesis was maintained, both secondary axis budburst rate and phytomer appearance rate were decreased, and individual leaf area slightly increased. Specific leaf area did not change under soil water deficit, whereas it increased under shading. These results confirm the existence of dynamic changes in organ sink strength and biomass allocation patterns to favour plant leaf area growth under shading, and to reduce plant leaf area and water losses by transpiration under water stress. From a modelling point of view, this study shows that functional structural models based on a C balance are not fully relevant for simulating plant growth under abiotic constraints if they do not include non-trophic relationships (hormonal signalling or plant hydraulic properties) that modify organ sink strength according to abiotic constraints.