scholarly journals Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation

2011 ◽  
Vol 15 (11) ◽  
pp. 3495-3510 ◽  
Author(s):  
M. Munz ◽  
S. E. Oswald ◽  
C. Schmidt
Keyword(s):  
Water Flux ◽  
Subsurface Water ◽  
Pass Band ◽  
Time Lags ◽  
Water Fluxes ◽  
Amplitude Ratios ◽  
Flux Calculation ◽  
Temperature Probe ◽  
Sand Box ◽  
Flow Velocities

Abstract. Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of ±1.3 m d−1. Pass band filtering provided amplitude differences and phase shifts of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to temperature sensor spacing, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small sensor distances of all setups were found to be insensitive to vertical water flux.

scholarly journals Sand box experiments to evaluate the influence of subsurface temperature probe design on temperature based water flux calculation

2011 ◽  
Vol 8 (3) ◽  
pp. 6155-6197 ◽  
Author(s):  
M. Munz ◽  
S. E. Oswald ◽  
C. Schmidt
Keyword(s):  
Water Flux ◽  
Subsurface Water ◽  
Pass Band ◽  
Time Lags ◽  
Water Fluxes ◽  
Amplitude Ratios ◽  
Flux Calculation ◽  
Temperature Probe ◽  
Sand Box ◽  
Flow Velocities

Abstract. Quantification of subsurface water fluxes based on the one dimensional solution to the heat transport equation depends on the accuracy of measured subsurface temperatures. The influence of temperature probe setup on the accuracy of vertical water flux calculation was systematically evaluated in this experimental study. Four temperature probe setups were installed into a sand box experiment to measure temporal highly resolved vertical temperature profiles under controlled water fluxes in the range of ±1.3 m d−1. Pass band filtered time series provided amplitude and phase of the diurnal temperature signal varying with depth depending on water flux. Amplitude ratios of setups directly installed into the saturated sediment significantly varied with sand box hydraulic gradients. Amplitude ratios provided an accurate basis for the analytical calculation of water flow velocities, which matched measured flow velocities. Calculated flow velocities were sensitive to thermal properties of saturated sediment and to probe distance, but insensitive to thermal dispersivity equal to solute dispersivity. Amplitude ratios of temperature probe setups indirectly installed into piezometer pipes were influenced by thermal exchange processes within the pipes and significantly varied with water flux direction only. Temperature time lags of small probe distances of all setups were found to be insensitive to vertical water flux.

Linking soil water and solutes fluxes to soil properties and vegetation types: insights from a case-study in the high tropical Andes of Ecuador

2021 ◽  
Author(s):  
Sebastián Páez-Bimos ◽  
Veerle Vanacker ◽  
Marcos Villacis ◽  
Marlon Calispa ◽  
Oscar Morales ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Conservation ◽  
Water Flux ◽  
Water Fluxes ◽  
Vegetation Types ◽  
Tropical Andes ◽  
Conservation Area ◽  
Solute Fluxes ◽  
Doc Concentration ◽  
Water Conservation Area

<p>The high tropical Andes ecosystem, known as páramo, provides important hydrological services to densely populated areas in the Andean region. In order to manage these services sustainably, it is crucial to understand the biotic and abiotic processes that control both water quality and fluxes. Recent research in the páramo highlights a knowledge gap regarding the role played by soil-vegetation interactions in controlling soil-water processes and resulting water and solute fluxes.</p><p>Here, we determine the hydrological and geochemical fluxes in four soil profiles in the páramo of the Antisana´s water conservation area in northern Ecuador. Water fluxes were measured biweekly with field fluxmeters in the hydrological year Apr/2019- Mar/2020 under two contrasting vegetation types: tussock-like grass (TU) and cushion-forming plants (CU). Soil solution was collected in parallel with wick samplers and suction caps for assessing the concentrations of dissolved cations, anions and organic carbon (DOC). In addition, soil moisture was measured continuously in the upper meter of the soil profile, i.e. first three horizons (A, 2A and 2BC), using water content reflectometers. The vertical water flux in the upper meter of each soil profile was simulated using the 1D HYDRUS model. We carried out a Sobol analysis to identify sensitive soil hydraulic parameters. We then derived water fluxes by inverse modeling, based on the measured soil moisture. We validated the calculated water fluxes using the fluxmeter data. Solute fluxes were estimated by combining the water fluxes and the soil solution compositions.</p><p>Our preliminary results suggest that water fluxes and DOC concentration vary under different vegetation types. The fluxmeter data from the 2A horizon indicates that the cumulative water flux under TU (2.8 - 5.7 l) was larger than under CU (0.8 – 1.1 l) during the dry season (Aug-Sep and Dec-Jan). However, the opposite trend was observed in the wet season for maximum water fluxes. Moreover, the DOC concentration in the uppermost horizon was higher under CU (47.3 ±2.2 mg l<sup>-1</sup>) than under TU (3.1 ±0.2 mg l<sup>-1</sup>) vegetation during the monitoring period. We associate the water and solute responses under different vegetation types to the contrasting soil hydro-physical and chemical properties (e.g., saturated hydraulic conductivity and organic carbon content) in the uppermost soil horizon. Our study illustrates the existence of a spatial association between vegetation types, water fluxes and solute concentrations in Antisana´s water conservation area. By modelling the hydrological balance of the upper meter of the soil mantle, the water and solute fluxes will be estimated for soils with different vegetation cover.</p><p> </p>

scholarly journals Stationary and Nonstationary Ion and Water Flux Interactions in Kidney Proximal Tubule: Mathematical Analysis of Isosmotic Transport by a Minimalistic Model

2019 ◽  
pp. 101-147 ◽  
Author(s):  
Erik Hviid Larsen ◽  
Jens Nørkær Sørensen
Keyword(s):  
Water Uptake ◽  
Time Course ◽  
Epithelial Transport ◽  
Water Flux ◽  
Experimental Studies ◽  
Physiological Parameter ◽  
Water Fluxes ◽  
Fluid Absorption ◽  
Knock Out ◽  
Osmotic Permeability

AbstractOur mathematical model of epithelial transport (Larsen et al. Acta Physiol. 195:171–186, 2009) is extended by equations for currents and conductance of apical SGLT2. With independent variables of the physiological parameter space, the model reproduces intracellular solute concentrations, ion and water fluxes, and electrophysiology of proximal convoluted tubule. The following were shown: Water flux is given by active Na+ flux into lateral spaces, while osmolarity of absorbed fluid depends on osmotic permeability of apical membranes. Following aquaporin “knock-out,” water uptake is not reduced but redirected to the paracellular pathway. Reported decrease in epithelial water uptake in aquaporin-1 knock-out mouse is caused by downregulation of active Na+ absorption. Luminal glucose stimulates Na+ uptake by instantaneous depolarization-induced pump activity (“cross-talk”) and delayed stimulation because of slow rise in intracellular [Na+]. Rate of fluid absorption and flux of active K+ absorption would have to be attuned at epithelial cell level for the [K+] of the absorbate being in the physiological range of interstitial [K+]. Following unilateral osmotic perturbation, time course of water fluxes between intraepithelial compartments provides physical explanation for the transepithelial osmotic permeability being orders of magnitude smaller than cell membranes’ osmotic permeability. Fluid absorption is always hyperosmotic to bath. Deviation from isosmotic absorption is increased in presence of glucose contrasting experimental studies showing isosmotic transport being independent of glucose uptake. For achieving isosmotic transport, the cost of Na+ recirculation is predicted to be but a few percent of the energy consumption of Na+/K+ pumps.

scholarly journals PREPARATION OF AN ORGANOSILICA-BASED MEMBRANE FROM TEOS-MTES AND ITS APPLICATION FOR DESALINATION OF WETLAND SALINE WATER

Konversi ◽  
2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Lilis Septyaningrum ◽  
Rahmawati Rahmawati ◽  
Fitri Ria Mustalifah ◽  
Aulia Rahma ◽  
Dewi Puspita Sari ◽  
...  
Keyword(s):  
Saline Water ◽  
Sol Gel ◽  
Water Flux ◽  
Water Desalination ◽  
Clean Water ◽  
Water Fluxes ◽  
Salt Rejection ◽  
Membrane Performance ◽  
Wetland Water ◽  
Hot Season

When hot season, South Kalimantan society which especially, in Muara Halyung village frequently go through clean water lacking. It becomes worst by water dirtied on wetland aquifer aftermath the seawater intrusion. Wetland water sources become saline and cannot be used for household needs. Organosilica membrane technology is one of methods can be used to remove salt contain in water. This study aims are to investigate the functionalization and organosilica membrane performance from TEOS-MTES which calcined on particularly temperature for wetland saline water desalination. Synthesis of organosilica sol was conducted by sol-gel method. Then the dried sol was calcined at 350°C and 600 °C, and characterized by FTIR (Fourier Transform InfraRed). Subsequently organosilica membrane was applicated for wetland saline water desalination via pervaporation. The result shows organosilica membrane performance was obtained the water flux 10,55 and 0,87 kg.m-2h-1 which calcined at 350 and 600 °C. The salt rejection in all membrane exhibits extremely high over 99%. It evinces the organosilica membrane from TEOS-MTES which calcined at 350 °C is great to applicated for wetland saline water desalination by both of water fluxes and salt rejection showed high.

scholarly journals Coupled modelling of subsurface water flux for an integrated flood risk management

2009 ◽  
Vol 9 (4) ◽  
pp. 1277-1290 ◽  
Author(s):  
T. Sommer ◽  
C. Karpf ◽  
N. Ettrich ◽  
D. Haase ◽  
T. Weichel ◽  
...  
Keyword(s):  
Flood Risk ◽  
Data Exchange ◽  
Subsurface Water ◽  
Flood Event ◽  
Causal Process ◽  
Water Fluxes ◽  
Sewerage System ◽  
Flood Water ◽  
Coupled Modelling ◽  
Groundwater Levels

Abstract. Flood events cause significant damage not only on the surface but also underground. Infiltration of surface water into soil, flooding through the urban sewer system and, in consequence, rising groundwater are the main causes of subsurface damage. The modelling of flooding events is an important part of flood risk assessment. The processes of subsurface discharge of infiltrated water necessitate coupled modelling tools of both, surface and subsurface water fluxes. Therefore, codes for surface flooding, for discharge in the sewerage system and for groundwater flow were coupled with each other. A coupling software was used to amalgamate the individual programs in terms of mapping between the different model geometries, time synchronization and data exchange. The coupling of the models was realized on two scales in the Saxon capital of Dresden (Germany). As a result of the coupled modelling it could be shown that surface flooding dominates processes of any flood event. Compared to flood simulations without coupled modelling no substantial changes of the surface inundation area could be determined. Regarding sewerage, the comparison between the influx of groundwater into sewerage and the loading due to infiltration by flood water showed infiltration of surface flood water to be the main reason for sewerage overloading. Concurrent rainfalls can intensify the problem. The infiltration of the sewerage system by rising groundwater contributes only marginally to the loading of the sewerage and the distribution of water by sewerage has only local impacts on groundwater rise. However, the localization of risk areas due to rising groundwater requires the consideration of all components of the subsurface water fluxes. The coupled modelling has shown that high groundwater levels are the result of a multi-causal process that occurs before and during the flood event.

scholarly journals A Theory of Water Percolation in Snow

1972 ◽  
Vol 11 (63) ◽  
pp. 369-385 ◽  
Author(s):  
S. C. Colbeck
Keyword(s):  
Water Saturation ◽  
Water Flux ◽  
Surface Flux ◽  
Gravity Drainage ◽  
Water Fluxes ◽  
Periodic Surface ◽  
Water Percolation ◽  
Wave Forms ◽  
Particular Solution ◽  
Measured Water

Abstract A theory is developed to describe the vertical percolation of water in isothermal snow. The general theory of Darcian flow is reviewed to establish a reasonable physical basis for the construction of a model. It is shown that in simple gravity drainage, capillarity is negligible compared with gravity since values of water saturation are generally in the “mid-range”. It is postulated that the permeability to the water phase increases as a certain function of the water saturation, and porosity is assumed to decrease linearly with depth. Ice layers and other inhomogeneities are treated in the theory by considering the permeability of the snow with the inhomogeneities included. A method by which this value of permeability can be calculated is presented using the method of characteristics. The theory is applied to the Seward Glacier firn where Sharp measured water fluxes at various depths. A periodic surface flux is assumed and the particular solution for water flux at any depth is given. From this solution the wave forms passing each depth are constructed and compared with the measured ones. Although the experimental data are affected by the presence of ice layers, the comparison between theory and experiment is favorable and the theory is thought to be essentially correct.

Hot or not? The effect of stemflow on infiltration and soil properties

2021 ◽  
Author(s):  
Johanna Clara Metzger ◽  
Janett Filipzik ◽  
Beate Michalzik ◽  
Anke Hildebrandt
Keyword(s):  
Soil Properties ◽  
Water Flux ◽  
Chemical Properties ◽  
Basal Area ◽  
Forest Plot ◽  
Water Fluxes ◽  
Soil Infiltration ◽  
Infiltration Capacity ◽  
Data Set ◽  
Funneling Ratio

<p>Stemflow can form hotspots of precipitation in forests. The stemflow funneling ratio describes the degree of concentration compared to open land rainfall in reference to the tree basal area. But how strongly does stemflow actually concentrate at the point of precipitation input to the soil? This depends on the size of stemflow infiltration areas. Findings hereon vary widely, as they refer to different tree and rainfall characteristics. Furthermore, due to little representative data on stemflow and the separate evaluation of stemflow and throughfall, the importance of stemflow as a hotspot is still subject to controversy. Using an extensive and representative field data set, we want to investigate the effect of stemflow on soil infiltration and percolation. Measurements were conducted on a 1-ha mixed beech forest plot in central Germany with intermediate stemflow generation. In high-resolution statistical designs, stand precipitation (stemflow, n = 65, and throughfall, n = 350) were recorded during three summers, and soil undisturbed (n = 420) and disturbed (n = 100) samples were taken and analyzed for physical and chemical properties. We calculated the spatial distribution of infiltration from stand precipitation data, rain intensity and soil infiltration capacity. Soil properties near stems (< 1m) and farther away were compared to determine a stemflow impact. Results show that stemflow infiltration areas are very small. Stemflow funneling at infiltration exceeds the conventional funneling ratio. Therefore, infiltration depth (L m<sup>-2</sup>) within stemflow infiltration areas is multiples of throughfall, even at dripping points. Soil properties close to trees are significantly different from the bulk soil, suggesting an accelerated soil formation process and a more developed soil structure. Stemflow-induced high soil water fluxes can be identified as an important driver for this pattern. Thus, the hotspot character of stemflow is confirmed by our findings. Stemflow-induced hotspots persist during infiltration and percolation. What is more, they have a direct and significant impact on the soil environment. Soil hydraulic properties facilitate quick water fluxes near stems. Such, trees might establish water flux bypasses from the canopy to the deeper subsurface.</p>

Novel streaming potential and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone

2011 ◽  
Author(s):  
Scott B. Jones ◽  
Shmuel P. Friedman ◽  
Gregory Communar
Keyword(s):  
Soil Water ◽  
Vadose Zone ◽  
Water Flux ◽  
Streaming Potential ◽  
Subsurface Water ◽  
Measurement Tool ◽  
Nutrient Fluxes ◽  
Thermal Sensor ◽  
Sensor Development ◽  
Soil Water Flux

The “Novel streaming potential (SP) and thermal sensor techniques for monitoring water and nutrient fluxes in the vadose zone” project ended Oct. 30, 2015, after an extension to complete travel and intellectual exchange of ideas and sensors. A significant component of this project was the development and testing of the Penta-needle Heat Pulse Probe (PHPP) in addition to testing of the streaming potential concept, both aimed at soil water flux determination. The PHPP was successfully completed and shown to provide soil water flux estimates down to 1 cm day⁻¹ with altered heat input and timing as well as use of larger heater needles. The PHPP was developed by Scott B. Jones at Utah State University with a plan to share sensors with Shmulik P. Friedman, the ARO collaborator. Delays in completion of the PHPP resulted in limited testing at USU and a late delivery of sensors (Sept. 2015) to Dr. Friedman. Two key aspects of the subsurface water flux sensor development that delayed the availability of the PHPP sensors were the addition of integrated electrical conductivity measurements (available in February 2015) and resolution of bugs in the microcontroller firmware (problems resolved in April 2015). Furthermore, testing of the streaming potential method with a wide variety of non-polarizable electrodes at both institutions was not successful as a practical measurement tool for water flux due to numerous sources of interference and the M.S. student in Israel terminated his program prematurely for personal reasons. In spite of these challenges, the project funded several undergraduate students building sensors and several master’s students and postdocs participating in theory and sensor development and testing. Four peer-reviewed journal articles have been published or submitted to date and six oral/poster presentations were also delivered by various authors associated with this project. We intend to continue testing the "new generation" PHPP probes at both USU and at the ARO resulting in several additional publications coming from this follow-on research. Furthermore, Jones is presently awaiting word on an internal grant application for commercialization of the PHPP at USU. 

scholarly journals Fluid and solute transport across the retinal pigment epithelium: a theoretical model

2020 ◽  
Vol 17 (163) ◽  
pp. 20190735
Author(s):  
Mariia Dvoriashyna ◽  
Alexander J. E. Foss ◽  
Eamonn A. Gaffney ◽  
Rodolfo Repetto
Keyword(s):  
Ion Channels ◽  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Water Flux ◽  
Chemical Species ◽  
Osmotic Gradient ◽  
Water Fluxes ◽  
Fluid Accumulation

The retina is composed of two main layers—the neuroretina and the retinal pigment epithelium (RPE)—that are separated by a potential gap termed the sub-retinal space (SRS). Accumulation of fluid in the SRS may result in a retinal detachment. A key function of the RPE is to prevent fluid accumulation in the SRS by actively pumping fluid from this space to the choroid. We have developed a mathematical model of this process that incorporates the transport of seven chemical species: Na + , K + , Cl − , HCO 3 − , H + , CO 2 and H 2 CO 3 . This allows us to estimate solute and water fluxes and to understand the role of the different membrane ion channels. We have performed a global sensitivity analysis using the extended Fourier amplitude sensitivity test to investigate the relative importance of parameters in generating the model outputs. The model predicts that flow across the RPE is driven by an osmotic gradient in the cleft gap between adjacent cells. Moreover, the model estimates how water flux is modified in response to inhibition of membrane ion channels and carbonic anhydrase (CA). It provides a possible explanation for how CA inhibitors, which are used clinically to prevent fluid accumulation in the SRS, may be acting.

Sign in / Sign up

Export Citation Format

Share Document