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Using an inverse modelling approach to evaluate the water retention in a simple water harvesting technique

Using an inverse modelling approach to evaluate the water retention in a simple water harvesting technique

Abstract. In arid and semi-arid zones, runoff harvesting techniques are often applied to increase the water retention and infiltration on steep slopes. Additionally, they act as an erosion control measure to reduce land degradation haz- ards. Nevertheless, few efforts were observed to quantify the water harvesting processes of these techniques and to evaluate their efficiency. In this study, a combination of de- tailed field measurements and modelling with the HYDRUS- 2D software package was used to visualize the effect of an infiltration trench on the soil water content of a bare slope in northern Chile. Rainfall simulations were com- bined with high spatial and temporal resolution water content monitoring in order to construct a useful dataset for inverse modelling purposes. Initial estimates of model parameters were provided by detailed infiltration and soil water reten- tion measurements. Four different measurement techniques were used to determine the saturated hydraulic conductiv- ity (K sat ) independently. The tension infiltrometer measure-
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Water retention characteristics of peat and sand mixtures

Water retention characteristics of peat and sand mixtures

The hydrological characteristics of soils, such as water retention and the rate of water movement, depend, to a large degree on the total porosity and pore-size distribution of the material [13]. The soil water potential - moisture characte- ristics allow the calculation of effective pore size distribu- tion. Water retention curves make it possible to determine the amount of strongly bound water (pF higher than 4.2), which is an indicator of the presence of micropores in soil. The volume of mesopores can be calculated as a difference between water content at pF 2 and 4.2. The mesopore content in the soil corresponds to the content of water available for plants and the water content at pF 2.0 - 2.7 and 2.7 - 4.2 represents easily available and poorly available water respectively. The water content between saturation and pF 2 indicates the presence of macropores. In macro- pores, a rapid gravitational efflux of water takes place. It is called soil aeration capacity. Water capacity between pF 2.0 and 4.2 is called potentially useful retention, but below pF 4.2 water is unavailable for plants [17].
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Amendment incorporation to increase soil water retention

Amendment incorporation to increase soil water retention

New Zealand has followed global water use trends, with over 50% of the country’s allocatable fresh water being used for irrigation (Ministry for Environment & Stats NZ, 2017). New Zealand’s irrigated area has increased by 40% in the last 15 years; an expansion rate that is greater than any other country in the OECD (OECD, 2014). Agricultural irrigation is set to continue expanding, with a further 51% increase in irrigated areas planned for New Zealand’s Canterbury region (New Zealand Government, 2012) with much of this expansion occuring on vulnerable shallow soils (Carrick et al., 2013). The arrival of irrigation to these previously un-irrigated areas represents an example of the pursuit of “sustainable intensification” (Mueller et al., 2012), whereby the aim is to increase agriculutral production while maintaining or decreasing the current environmental impacts. This approach presents a problem as shallow stony soils are not well suited to irrigation because they are characterised by low soil water retention and rapid permeability (Carrick et al., 2013), two characteristics that are strongly correlated with increased nutrient leaching (Wheeler et al., 2011) and inefficient water use (Hatfield et al., 2001; Howell, 2001). Increasing irrigation on these shallow stony soils may contribute to an increase in nutrient leaching and poor water use efficiency, which may cause more environmental harm than economic good.
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Water retention characteristics of swelling clays in different compaction states

Water retention characteristics of swelling clays in different compaction states

which otherwise would have governed the capillary component of the suction. In such a case, the capillary component of suction, which depends on the clay microstructure, no more influences the SWRC and the adsorptive surface forces (viz., van der Waals surface forces) control the water retention behaviour of soils (Tuller and Or, 2005). This phenomenon may be expressed as loss of ‘clay-microstructure effect’. As such, the water retention characteristics of the clay becomes independent of the initial state of the clay (viz., undisturbed natural formation or reconstituted state) and/or (b) deformability (i.e., the shrinkage) of the pores during drying process which might result into similar pore-size distribution for the intact and reconstituted states, close to ψ c . With context to hypothesis (a), it is worth mentioning here that earlier studies
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Modelling of the water retention characteristic of deformable soils

Modelling of the water retention characteristic of deformable soils

This paper reports a model of the water retention characteristic of unsaturated porous media and its application on the residual shrinkage of deformable soils. The model is based on an equation of the state of the fluid in porous media established on the classical capillary theory. It explicitly take account of the effect of deformation and can be used to fit the measured SWRCs of different initial void ratios of a soil and constructs a general SWRS in the space of s-w-e. The tests on three soils have shown that the model works well in terms of the shape of the modelled SWRS and the calculated relative errors and residuals for modelling accuracy. The explanation on its performance is in agreement with the fundamental concepts and the assumptions of the model. By now, the model has been proved to work particularly well for high suction region when the capillary condensation plays a significant role. A further work to improve its performance at low suction region needs the consideration of the effect of the wetting water film on the empty pore surface. On another hand, it needs to be pointed out as well that modelling the water retention characteristic of deformable soils in terms of the soil- water retention surface is not enough. Further investigation in future needs to be able to explicitly describe each of the specific water retention curves of different initial void ratios in the space of s-w-e.
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Water retention of arctic zone soils (Spitsbergen)

Water retention of arctic zone soils (Spitsbergen)

The area of research covers the NW part of Wedel Jarlsberg Land (77°26’ – 77°35’N and 13°55’ – 14°54’E) (Klimowicz et al., 2008) (Fig. 1). The whole area is divided by lines of mountain ridges, between which there are val- leys widening towards the sea, in its proximity creating vast plains in the form of marine terraces. Water retention was determined for the soils formed on four characteristic micro-relief surface forms (Tedrow, 1977; Washburn, 1980): – Mud boils are circular and inconsiderable raised forms with a diameter between 50 and 70 cm. Very poor vegeta- tion and their light grey colour, which can be seen from a long distance, make an impression of ‘spots’. Therefore, larger surfaces of mud boils are often called the ‘spotted’ tundra or ‘spotted’ soils.
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The effects of heating without water removal and drying on the swelling as measured by water retention value and degradation as measured by intrinsic viscosity of cellulose papermaking fibers

The effects of heating without water removal and drying on the swelling as measured by water retention value and degradation as measured by intrinsic viscosity of cellulose papermaking fibers

For air drying (AD), the sheets in the rings were left to dry overnight at controlled conditions of 23°C and 50% RH. For heat drying, the sheets in the rings were placed in laboratory oven at the specified temperature for 15 minutes, then cooled for 5 minutes in the open atmosphere before being sealed in plastic bags. Sheets that were subjected to heat treatment were placed between two metal plates and tightened in the rings. They were then placed in a laboratory high-pressure digester. The digester was fed with saturated steam at approximately 140 psi (970 kPa) until the temperature reached the desired setpoint. The total treatment time was 15 minutes, after which the digester pressure was relieved, and the sheets were removed from the digester. The sheets were then cooled for 5 minutes in open air and transferred to sealed bags for cold storage. After treatment, the sheets were tested for 0.5 % Cupraethylenediamene (CED) viscosity and water retention value (WRV). Samples tested for viscosity were conditioned for 24 hours at 23°C and 50% RH. This process air-dried the samples that had been heated, and allowed moisture uptake by the sheets that were heat dried. The samples were then tested for viscosity according to TAPPI T 230 om-89. Samples were tested for WRV by using a modified version of TAPPI UM 256. Small samples of the pulp were dispersed in deionized water in a British Disintegrator (3000 rpm, 5 minutes, 1.2% consistency, and 2000 grams total) then allowed to soak for 24 hrs. The samples were then formed into pads on a no. 4 Fisher filter paper and dewatered to approximately 25% solids. Samples of the pad were weighed and placed in sintered centrifuge tubes (pore size 22 mm, volume 3 mL, provided by MSI). The samples were then centrifuged at 900 g f for 30 minutes.
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An alternative deterministic method for the spatial interpolation of water retention parameters

An alternative deterministic method for the spatial interpolation of water retention parameters

pirical way and do not have a physical meaning, the evalua- tion of these parameters has to be done with great care, or the results may be misleading and meaningless (Romano, 2004). However, there are still a number of studies that rely solely on water retention parameters, because one can dramatically reduce the number of parameters that need to be analyzed. For example, Zhu and Mohanty (2002) averaged the widely used van Genuchten “parameters” to simulate large-scale in- filtration and evaporation processes. In Oliveira et al. (2006), stochastic fields of “parameters” were generated using condi- tioning parameters to simulate variably-saturated water flow in soils. In some studies, the number of parameters is even re- duced to one or two by using the scaling method (e.g., Shouse et al., 1995; Oliveira et al., 2006). The question then arises whether or not we can consider these derived (i.e., averaged or randomly generated) parameters to be equivalent to ex- perimentally measured soil physical properties, such as volu- metric water contents. In other words, to map water retention parameters, which approach, FI or IF, should we take?
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REGULARITIES OF WATER RETENTION PROCESS BY FIR-TREE NEEDLE SAMPLES

REGULARITIES OF WATER RETENTION PROCESS BY FIR-TREE NEEDLE SAMPLES

In brochure [1] the proposed criterion is needle moisture mass halves loss time. However, termination of needle sample weighings after loss more than 50 % of their initial mass results in impossibility of deter- mination of such water retention process dy- namics parameters both an initial mass of a moisture in sample, first passage time of a room air-dry mass and mean deliquification rate of sample. Thus, the existent methods of desiccation estimation don t allow to measure parameters of water retention and desiccation processes, and also to conduct analysis of
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Point pedotransfer functions for estimating soil water retention curve

Point pedotransfer functions for estimating soil water retention curve

A b s t r a c t. Soil water retention curve (SWRC) is one of the most important soil hydraulic properties, whose estimation is still under consideration. In this study, we used 315 soil samples from the UNSODA database to develop three models of point pedo- transfer functions (PTFs) and to verify them. We also used an inde- pendent database, GRIZZLY, with 59 samples, to verify the deve- loped point PTFs and to compare them with the Rosetta model. Multiple linear regression and stepwise methods were used to derive pedotransfer functions. In the first model, soil texture data ie sand, silt, and clay content, geometric mean particle-size diameter and geometric standard deviation as well as bulk density were used to develop point PTFs at 10 matric potentials. In the second model, water content at field capacity, and in the third model water content at field capacity and permanent wilting point were also used for developing PTFs at 9 and 8 matric potentials, respectively. To eva- luate the accuracy and reliability of the point PTFs, we used cross- validation eg repeated random splitting of the data set into subsets for development and validation. The calculated RMSE values showed that all three developed point PTFs estimated soil water retention curve better than the Rosetta model.
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Evaluation of compost influence on soil water retention

Evaluation of compost influence on soil water retention

moisture sensors. Results showed that application of compost of above mentioned doses positively aff ected water retention of the soil. Organic matter, applied at the above mentioned amount has a positive eff ect on soil moisture retention, regardless of possible infl uence of soil type, grassing and amount of rainfalls. Outcomes of experiment become bases for recommended compost doses as well as for technical proposal of compost application processes.

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Study of Using Paper Filter Whatman no.42 for Measuring Water Retention in Cement Paste

Study of Using Paper Filter Whatman no.42 for Measuring Water Retention in Cement Paste

This paper present that study of using paper filter Whatman no.42 for measuring water retention in cement paste. The research is conducted as experiment in D3 civil engineering ITS laboratory. The experiment use modelling specimens with two types. They are cement paste with variation water cement ratio value and foam cement paste. Value of water cement ratio be used by 0.5, 0.45, 0.35 and 0.3. Destination of modelling specimen cement paste with variation water cement ratio and foam cement paste is to obtain different of porosity. The specimen can be tested after 28 days curing. The experiment is measuring water retention on cement paste and foam cement paste with using paper filter Whatman no. 42 to obtain water retention curve. Before measurement water retention, previously testing to determine parameter time of consistency water content on specimen (t 1 ).
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STUDY ON THE FACTORS INFLUENCING HYDRATION AND WATER RETENTION CAPACITY OF MEAT

STUDY ON THE FACTORS INFLUENCING HYDRATION AND WATER RETENTION CAPACITY OF MEAT

Top-quality food produce and high profitability in processing requires high quality in raw materials. Therefore, to achieve these objectives, it is imperative to know the properties of the war materials, and the factors that influence these properties.The properties of the meat directly involved in increasing economic efficiency and final produce quality are the so-called technological properties: hydration capacity and water retention capacity of meat. These properties are determined by some factors belonging to the intrinsic quality of meat, animal slaughter methods, technological operations applied to the meat, and the auxiliary materials used.
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A Review on Water Retention

A Review on Water Retention

High levels of certain hormones can also make your body hold on to water. These include insulin,which is needed to process sugar; cortisone, which is produced when you are under stress; and the female hormones oestrogen (estrogen) and progesterone. The waterretaining effect is caused by the effects which these hormones have on sodium levels in your body, and on the hormones which govern how your kidneys work. Certain prescribed medicines such as the contraceptive pill and some painkillers can be causes of water retention by affecting levels of these hormones. Causes of Water Retention | About Water Retention The Tissue Spaces. The round objects represent cells which receive nutrients from the blood capillary and send wastes to the capillary. Water retention which is caused by hormones can be spread around the body but often affects your tummy most of all. Women can also get water retention in the breasts, which causes breast tenderness and swelling.
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Andisols Water Retention Under Peasant Oil Palm Plantation

Andisols Water Retention Under Peasant Oil Palm Plantation

The results of this research indicate that the Andisols in Pasaman sub-district with a slope more than 15%, planted with oil palm at age 10-15. Afterward, over 15 years, the had medium bulk density (BD) and high total pore space. Whereas, the land under oil palm at age 5-10 years had medium bulk density and entire pore space. Water retention of Andisols in Pasaman sub-district, planted with oil palm at the age of 10-15 and above 15 years old, had a very high class of available water (AW) and only on the land planted with palm at age 5- 10 years old, the water availability is high-class. Based on the land evaluation from soil physics aspect at the peasant oil palm plantation in Andisols in Pasaman sub-district, it can be concluded that there is no impact of oil palm at age 10-15 and above 15 years on the soil water deficit phenomenon. There is no correlation between the crop ages with water consumption. Andisols has a unique characteristic which consists of high content of allophane mineral, hollow spherules. This unique characteristic has a high absorbency of water from soil saturation
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On the role of soil water retention characteristic on aerobic microbial respiration

On the role of soil water retention characteristic on aerobic microbial respiration

at any given time, expressed as a fraction of the total ini- tial SOC, and the rate constant κ (day −1 ) is a measure of SOM decomposition largely driven by living decomposers. Therefore, we consider it to be a composite parameter that accounts for the abundance of decomposer population as well as the activity of an average decomposer. Both of these fac- tors are impacted when soil moisture level changes. Chowd- hury et al. (2011b) observed that the abundance of active de- composers declines while maintaining the same level of av- erage activity as water potential dropped from ψ = 0 kPa to ψ = − 2000 kPa. Organisms subjected to low total water po- tential exhibit reduced population growth as substantial pro- portion of their energy intake is routed towards osmoregu- lation (Harris, 1981; Watson, 1970). Upon further drying, however, the population remained constant, but the activity declined sharply (Chowdhury et al., 2011a, b). Previously, Stark and Firestone (1995) used two independent techniques to evaluate (a) the relative importance of water potential on cytoplasmic dehydration and (b) the role of water content diffusional limitations in controlling soil microbial activity. They used nitrifying (ammonium oxidizing) bacteria as a model system, in which nitrification rate was considered a surrogate for microbial activity. In the first experiment, they used well-mixed soil slurries, in which NH 4 was maintained
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Nitrogen surface water retention in the Baltic Sea drainage basin

Nitrogen surface water retention in the Baltic Sea drainage basin

Regarding statistical uncertainty in our study, the three land cover classes (and the surface water area) add up to 100 % and apparently these explanatory variables are inter- correlated. This will have less influence on the method ap- plied although there is always a risk of multicollinearity in these kinds of regression-type of models. It should be noted that the model inputs are areas of the land cover and not the percentages which will decrease the risk of multicollinear- ity. Experiences with the MESAW models, as also given in the previously quoted papers, in different geographical areas (Lidèn et al., 1999; Vassiljev and Stålnacke, 2005; Vassiljev et al., 2008; Povilaitis et al., 2012) have not indicated any problem with possible interrelated explanatory variables. In addition, the parameter estimates showed reasonable stabil- ity; little change occurred in the values of the most statisti- cally significant model coefficients when additional variables were added in exploratory regressions (Table 1).
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REGULARITIES OF WATER RETENTION PROCESS BY CUT FIR-TREE RAMULUSES

REGULARITIES OF WATER RETENTION PROCESS BY CUT FIR-TREE RAMULUSES

The plants, especially woody, are ca- pable to occlude many industrial discharging components [1]. Therefore ecological evalua- tion of territories can be conducted by fir-tree needle properties. An ecological state of for- est ecosystem is evaluated using physiologi- cal parameters [2]. However in the known publications deliquification and water reten- tion ability of fir-tree needles are unsuffi- ciently investigated and the estimated pa- rameters as applied to diagnostics of pollu- tion about a fir-tree habitat are not devel- oped.

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Scaling the hydraulic functions of a water repellent sandy soil

Scaling the hydraulic functions of a water repellent sandy soil

The approach of scaling is commonly applied in the field of hydrology, but it has also been applied to the hy- draulic functions in soil science. Sposito (1998) gives an overview of scaling in hydrology and soil science. Most in- vestigations on the hydraulic functions were made using water retention data (Deurer et al., 2000; Kosugi and Hop- mans, 1998; Millan and Gonzalez-Posada, 2005), much fewer were carried out using the unsaturated hydraulic con- ductivity. Clausnitzer et al. (1992) introduced an algorithm to scale simultaneously conductivity and water retention. Using two sets of data, they proved the feasibility of this concept. Rockhold et al. (1996) applied it successfully for simulation of the water flow and tritium transport. Tuli et al. (2001) applied a physically based scaling approach of Kosugi and Hopmans (1998) on 143 soil samples. They were able to show that the theoretical interpretation of a log normal dis- tribution of scaling factors was applicable to the simulta- neous scaling of hydraulic functions. Other authors came to independent scaling functions for unsaturated conductivity and water retention. Hendrayanto et al. (2001) measured unsaturated conductivity and water retention for six soil profiles in a forestry soil and scaled the measurements for Int. Agrophys., 2014, 28, 349-358
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Impact of land use on water properties of rendzinas

Impact of land use on water properties of rendzinas

A b s t r a c t. The human agricultural activity leads to very strong changes in the soil – even the period of several decades of fallowing as well as the restitution of potential vegetation commu- nities are not able to level those transformations. The climatic changes and agricultural use discontinuation from calcareous soils are caused to coming into existence the climax forest communi- cations on these areas. Rendzinas that were agriculturally used in the past, despite the development of secondary xerothermic swards differ in their hydrophysical properties from the soils occupied by the primary swards. In this work the impact of the way of land use and the natural successive transformations of vegetation on the hydrophysical properties of rendzinas were shown. The surface ho- rizons of cultivated and fallow rendzinas (in comparison with the respective horizons of soils overgrown by primary xerothermic vegetation) are characterized by greater bulk density, lower water retention in the full range of the studied soil water potentials, smal- ler number of pores, especially of the large pores (dia > 18.5 µm). Water retention and conductivity for soil water potential >1 hPa of surface horizons of fallow rendzinas are close to the values that are characteristic for soils overgrown by shrubs, this being a possible cause of the instability of secondary xerothermic swards as well as of the fast rate of succession in the direction of shrub and forest communities.
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