scholarly journals Measurement of unsaturated meltwater percolation flux in seasonal snowpack using self-potential

2021 ◽  
pp. 1-16
Author(s):  
Wilson S. Clayton
Keyword(s):  
Method Development ◽  
Water Saturation ◽  
Field Measurements ◽  
Time Domain Reflectometry ◽  
Electrode Spacing ◽  
Glacier Mass Balance ◽  
Wetting Front ◽  
Electrical Field Strength ◽  
Water Redistribution ◽  
Self Potential

Abstract This paper presents a feasibility study of in situ field measurements of unsaturated meltwater percolation flux within the vertical profile of a snowpack, using the self-potential (SP) method. On-site snowmelt column tests calibrated the SP measurements. The SP data measured electrical field strength with an electrode spacing of 20 cm, and coincident water saturation (Sw) measurements using time domain reflectometry allowed calculation of SP-modeled vertical percolation flux (qsp), expressed as Darcy velocity. The results reflected transient diurnal snowmelt dynamics, with peak flux lagging arrival of a saturation wetting front. Peak daily qsp was 60 to >300 mm d−1, whereas daily snowmelt was 20–50 mm w.e. Surface refreezing events appeared to cause upward flow, possibly representing water redistribution toward the freezing boundary. Calculated fluxes were comparable to actual fluxes, although average errors ranged from −15 to +46% compared to average of melt expected from surface energy-balance and ablation stake measurements. By advancing method development to measure unsaturated meltwater percolation flux in snowpacks this study creates opportunities to study fundamental snowmelt processes, may improve mathematical modeling and may supplement glacier mass-balance studies and studies of snowmelt interactions with avalanches, groundwater and surface water.

scholarly journals CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO

Irriga ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 564-577 ◽  
Author(s):  
Leonardo Do Nascimento Lopes ◽  
Elton Martins ◽  
Bruno De Lima Santoro ◽  
Claudinei Fonseca Souza
Keyword(s):  
Water Content ◽  
Time Domain ◽  
Water Distribution ◽  
Water Storage ◽  
Time Domain Reflectometry ◽  
Wetting Front ◽  
Applied Water ◽  
Flow Rates ◽  
Abstract Knowledge ◽  
The Time Domain

CARACTERIZAÇÃO DA DISTRIBUIÇÃO DA ÁGUA NO SOLO PARA IRRIGAÇÃO POR GOTEJAMENTO  Leonardo do Nascimento Lopes1; Elton Martins2; Bruno de Lima Santoro2; Claudinei Fonseca Souza31Universidade de Taubaté, Unitau, Taubaté, SP,  [email protected] Engenharia Civil e Ambiental, Universidade de Taubaté, Taubaté, Unitau, SP 3Departamento de Recursos Naturais e Proteção Ambiental, Universidade Federal São Carlos, São Carlos, SP  1 RESUMO O conhecimento da distribuição da água no solo é de grande importância para a agricultura, uma vez que a água é um dos fatores que mais influenciam o rendimento das culturas. Existem muitas técnicas utilizadas para o monitoramento do conteúdo de água do solo, a reflectometria domínio do tempo (TDR) tem sido difundida entre os pesquisadores por apresentar várias vantagens, entre as quais a determinação em tempo real e a possibilidade de leituras automatizadas. O principal objetivo desta pesquisa foi avaliar a distribuição da água no perfil de um Latossolo Vermelho-Amarelo. Sondas de Reflectometria no domínio do Tempo (TDR) foram utilizadas para monitorar a distribuição de água no solo aplicada através de gotejadores de fluxo constante nas taxas de 2, 4 e 8 Lh-1. Considerando os resultados de diferentes perfis, observa-se um maior armazenamento da água próximo do gotejador diminuindo progressivamente para frente de molhamento. Aproximadamente, um terço da água aplicada (33%) foi armazenado na primeira camada (0-0,10 m) para todos os ensaios. Comparando diferentes taxas de aplicação, observa-se maior armazenamento de água para o gotejador de 8L h-1, com 30, 33 e 34% de água aplicada acumulada na primeira camada (0-0.10 m) para gotejadores de 2, 4 e 8L h-1, respectivamente. Os resultados sugerem que, com base no volume e frequência utilizada neste experimento, seria vantajoso aplicar pequenas quantidades de água em intervalos mais frequentes para reduzir perdas por percolação. UNITERMOS: TDR, conteúdo de água, bulbo molhado  LOPES, L. N.; MARTINS, E.; SANTORO, B. L.; SOUZA, C. F.WATER DISTRIBUTION CHARACTERIZATION IN SOIL FOR DRIP IRRIGATION   2 ABSTRACT Knowledge of water distribution in soil is of great importance to agriculture, since water is one of the factors that most influence the yield of crops. There are many techniques used to monitor soil water content. The time domain reflectometry (TDR) has been widespread among researchers because it presents several advantages, among which the determination in real time and possibility of automated readings. The main goal of this research was to evaluatethe water distribution in a profile of Red-Yellow Oxisol. Time domain reflectometry (TDR) probes were used to monitor the water distribution from drippers discharging at constant flow rates of 2, 4 and 8 Lh-1 in soil. Considering results from different profiles, we observed greater water storage near the dripper decreasing gradually towards the wetting front. About one third of the applied water (33%) was stored in the first layer (0-0.10 m) for all experiments. Comparing different dripper flow rates, we observed higher water storage for 8 L h-1, with 30, 33 and 34% of applied water accumulating in the first layer (0-0.10m) for dripper flow rates of 2, 4 and 8 L h-1, respectively. The results suggest that based on the volume and frequency used in this experiment, it would be advantageous to apply small amounts of water at more frequent intervals to reduce deep percolation losses of applied water. KEYWORDS: TDR, water content, wetted soil volume

Experimental determination of bulk dielectric properties and porosity of porous asphalt and soils using GPR and a cyclic moisture variation technique

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. K93-K102 ◽  
Author(s):  
W. L. Lai ◽  
W. F. Tsang ◽  
H. Fang ◽  
D. Xiao
Keyword(s):  
Water Saturation ◽  
Complex Refractive Index ◽  
Large Mass ◽  
Small Mass ◽  
Time Domain Reflectometry ◽  
Water Permeation ◽  
Moisture Variation ◽  
Wide Range ◽  
Test Materials ◽  
Variation Technique

This paper describes a new method for determining porosities in two porous construction and geologic materials (asphalt and soil) by using ground-penetrating radar (GPR) over a wide range of controlled degrees of water saturation [Formula: see text]. We call this method a cyclic moisture variation technique (CMVT). Freshwater is used as an enhancer or a tracer to allow GPR to easily detect and differentiate amounts of water or other moisture in these materials. The CMVT is based on measuring the changes of real permittivity [Formula: see text] and [Formula: see text] in the test materials as they transition from partially saturated states to a fully saturated state via cycles of water permeation and dewatering. This method does not disturb the test materials, as do the methods associated with traditional laboratory testing on cored samples. It also tests a large mass of in situ material, compared with the small mass tested by the conventional or electromagnetic coaxial transmission line (EMCTL) method (also known as a dielectric cell) and the time-domain reflectometry (TDR) method. Porosity values of asphalt [Formula: see text] and of soils [Formula: see text] were determined by fitting the data into the complex refractive index model (CRIM). Dielectric hysteresis of both soils and asphalt also is observable during the tests and shows that the pathways of water-ingress and water-egress processes are not identical in the plot of [Formula: see text] versus degrees of water saturation [Formula: see text].

scholarly journals Influence of Microsprinkler Irrigation Amount on Water, Soil, and pH Profiles in a Coastal Saline Soil

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Linlin Chu ◽  
Yaohu Kang ◽  
Shuqin Wan
Keyword(s):  
Saline Soil ◽  
Column Experiment ◽  
Northern China ◽  
Potential Method ◽  
Soil Salinization ◽  
Wetting Front ◽  
Irrigation Amount ◽  
Coastal Saline Soil ◽  
Water Redistribution ◽  
Water Amount

Microsprinkler irrigation is a potential method to alleviate soil salinization. After conducting a homogeneous, highly saline, clayey, and coastal soil from the Bohai Gulf in northern China in a column experiment, the results show that the depth of the wetting front increased as the water amount applied increased, low-salinity and low-SAR enlarged after irrigation and water redistribution, and the soil pH increased with an increase in irrigation amount. We concluded that a water amount of 207 mm could be used to reclaim the coastal saline soil in northern China.

Looking high and low: comparing a UAV-based and a ground-based methodology for the detection of vineyard terrace failures

2020 ◽  
Author(s):  
Anton Pijl ◽  
Edoardo Quarella ◽  
Teun A. Vogel ◽  
Vincenzo D'Agostino ◽  
Paolo Tarolli
Keyword(s):  
Remote Sensing ◽  
Surface Water ◽  
Water Concentration ◽  
Field Measurements ◽  
Time Domain Reflectometry ◽  
Terrain Analysis ◽  
Topographic Wetness Index ◽  
Cross Sectional ◽  
Spatially Distributed ◽  
Dry Conditions

<p>Agricultural terraces are known to be related to complex hillslope hydrology, characterized by surface and sub-surface water flows. Locally high fluxes or accumulation of water can be responsible for terrace wall failures, such as collapse and piping. There is a need for both scientific research and applied sustainable viticulture to better understand these processes. A key challenge is to find a suitable balance between highly integrated but local field measurements, and a more approximate but widespread approach such as remote sensing. In this study, two distinctive methodologies were applied in order to locate and explain terrace wall failure observed in a north-Italian vineyard: a field-based vs. a remote sensing approach. The field-based approach was based on spatially distributed measurements of topsoil soil moisture content using Time Domain Reflectometry (TDR) instrument. This survey revealed high relative soil water concentration at the damaged terraces, in both wet and dry conditions. Furthermore, a unique cross-sectional saturation profile was found above the damaged walls, with the highest values found near the edges. The remote sensing approach was based on a photogrammetric survey and subsequent high-resolution digital terrain analysis and modeling using the Topographic Wetness Index (TWI) and SIMulated Water Erosion model (SIMWE). Results showed how the formation of surface water flow patterns explains the location of damaged walls. These findings show both the opportunities and limitations of the two approaches. Field measurements provided more conclusive information about the location of walls at risk (high predictive potential), but this approach is relatively labour-intensive (low upscaling potential) as compared to a remote sensing approach. The latter can be a powerful tool for acquiring fully distributed estimations of wall failure over larger non-instrumented areas.</p>

scholarly journals Measurements and modeling of snow albedo at Alerce Glacier, Argentina: effects of volcanic ash, snow grain size, and cloudiness

2020 ◽  
Vol 14 (12) ◽  
pp. 4581-4601
Author(s):  
Julián Gelman Constantin ◽  
Lucas Ruiz ◽  
Gustavo Villarosa ◽  
Valeria Outes ◽  
Facundo N. Bajano ◽  
...  
Keyword(s):  
Grain Size ◽  
Mass Balance ◽  
Volcanic Ash ◽  
Impurity Content ◽  
Field Measurements ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Snow Albedo ◽  
The Impact

Abstract. The impact of volcanic ash on seasonal snow and glacier mass balance has been much less studied than that of carbonaceous particles and mineral dust. We present here the first field measurements on the Argentinian Andes, combined with snow albedo and glacier mass balance modeling. Measured impurity content (1.1 mg kg−1 to 30 000 mg kg−1) varied abruptly in snow pits and snow and firn cores, due to high surface enrichment during the ablation season and possibly local or regional wind-driven resuspension and redeposition of dust and volcanic ash. In addition, we observed high spatial heterogeneity, due to glacier topography and the prevailing wind direction. Microscopic characterization showed that the major component was ash from recent Calbuco (2015) and Cordón Caulle (2011) volcanic eruptions, with a minor presence of mineral dust and black carbon. We also found a wide range of measured snow albedo (0.26 to 0.81), which reflected mainly the impurity content and the snow and firn grain size (due to aging). We updated the SNow, ICe, and Aerosol Radiation (SNICAR) albedo model to account for the effect of cloudiness on incident radiation spectra, improving the match of modeled and measured values. We also ran sensitivity studies considering the uncertainty in the main measured parameters (impurity content and composition, snow grain size, layer thickness, etc.) to identify the field measurements that should be improved to facilitate the validation of the snow albedo model. Finally, we studied the impact of these albedo reductions on Alerce Glacier using a spatially distributed surface mass balance model. We found a large impact of albedo changes on glacier mass balance, and we estimated that the effect of observed ash concentrations can be as high as a 1.25 m water equivalent decrease in the annual surface mass balance (due to a 34 % increase in the melt during the ablation season).

scholarly journals Spatial and temporal characterization of water and solute distribution patterns

2010 ◽  
Vol 67 (1) ◽  
pp. 09-15 ◽  
Author(s):  
Claudinei Fonseca Souza ◽  
Marcos Vinícius Folegatti
Keyword(s):  
Crop Production ◽  
Distribution Patterns ◽  
Potassium Nitrate ◽  
Time Domain Reflectometry ◽  
Solute Distribution ◽  
Management Systems ◽  
Wetting Front ◽  
Gradient Distribution ◽  
Constant Flow Rate

The use of drip irrigation and marginal water is growing rapidly in some areas, highlighting the need to develop sound fertigation practices that combine environmental and crop production concerns. In this study the spatial and temporal water and solute distribution patterns are characterized to underpin fertirrigation design and management systems. Time domain reflectometry (TDR) probes were used to monitor the distributions of potassium nitrate (KNO3) and water from drippers discharging at a constant flow rate of 4 L h-1 in soil-filled containers. In the interactions between the different profiles, a gradient distribution of the solution in the soil was observed, with greater storage of solution close to the dripper, which decreased gradually as it approached the wetting front. To reduce leaching of fertigated ions, the frequent application of small amounts of solution during irrigation is recommended.

Self‐potentials associated with the Yanacocha high‐sulfidation gold deposit in Peru

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 684-689 ◽  
Author(s):  
Mark Goldie
Keyword(s):  
Apparent Resistivity ◽  
Direct Relationship ◽  
Field Measurements ◽  
Gold Deposits ◽  
Mineral Deposits ◽  
Silica Body ◽  
High Sulfidation ◽  
Extensive Field ◽  
Self Potential ◽  
Peak Value

Significant self‐potential (SP) anomalies characterize the large silica bodies associated with high‐sulfidation oxide gold deposits in the Yanacocha district, Peru. Large SP effects and high apparent resistivities have been observed that coincide with areas of intense silicification. Negative SP anomalies of several volts have been routinely recorded on numerous projects and deposits. The peak value measured was −10.2 V. A direct relationship is shown to exist between the magnitude of an SP response and the size and apparent resistivity of a silica body. Extensive field measurements over numerous high‐sulfidation deposits show that the negative SP effect increases with the size and/or resistivity contrast associated with these unique mineral deposits.

Inversion of low-induction number conductivity meter data to predict seasonal saturation variation

Geophysics ◽  
2011 ◽  
Vol 76 (6) ◽  
pp. F395-F406 ◽  
Author(s):  
Adam Smiarowski ◽  
James Macnae ◽  
Glen Bann
Keyword(s):  
Electrical Conductivity ◽  
Half Space ◽  
Water Saturation ◽  
Joint Inversion ◽  
A Priori ◽  
Field Measurements ◽  
Bottom Layer ◽  
Near Surface ◽  
South Wales ◽  
Better Than

Our research introduced a method to monitor saturation in the near surface. In agricultural settings, methods measuring electrical conductivity can provide useful information about soil type, moisture content, and salinity extent. Electrical conductivity meters have been used in a number of studies to determine soil properties in a qualitative sense. We examined the range of structures in which the use of low-induction number instruments can be used successfully to determine layered-earth electrical conductivity. We used an inversion routine which employs a Bayesian modification to the ridge-regression technique with a priori conductivity assumptions typical of agricultural areas. We performed joint inversion of horizontal and vertical dipole configurations at two coil separations for layer over half-space models with electrical properties of silt, loam, clay, and saline waters. Generally, the inversion code resolved layer thickness to better than 25% and electrical conductivity to better than 20% if the layer is less than 3-m thick. We then inverted field measurements acquired in salt-scalded areas in the Yass River Valley, New South Wales, Australia, to determine a layer over a half-space. With Kennedy’s formulation concerning the relationship between porosity, water saturation and electrical conductivity, we used the field results to predict autumn water saturation for the top layer to be 13% and the bottom layer to be 15%. In the spring, we used the field results to predict saturation of 50% for the top layer and 51% for the bottom layer, leading to a seasonal variation in soil saturation of approximately 36%. Predicted saturation was spatially consistent across the traverse line, suggesting that the developed methodology was successful.

scholarly journals COMPARAÇÃO ENTRE CURVAS DE RETENÇÃO DE ÁGUA OBTIDAS EM LABORATÓRIO E A CAMPO

Irriga ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 125-142
Author(s):  
Rafael Gotardo ◽  
Adilson Pinheiro ◽  
Vander Kaufmann ◽  
Gustavo Antonio Piazza ◽  
Edson Torres
Keyword(s):  
Linear Regression ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Measurements ◽  
Sao Paulo ◽  
Time Domain Reflectometry ◽  
Native Forest ◽  
São Paulo ◽  
Land Uses

COMPARAÇÃO ENTRE CURVAS DE RETENÇÃO DE ÁGUA OBTIDAS EM LABORATÓRIO E A CAMPO     RAFAEL GOTARDO1; ADILSON PINHEIRO2; VANDER KAUFMANN3; GUSTAVO ANTONIO PIAZZA4 E EDSON TORRES5   1Eng. Agrônomo, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil,  [email protected]. 2Eng. Civil, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 3Químico, Biólogo, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 4Eng. Ambiental, Doutor, Programa de Pós-Graduação em Engenharia Ambiental (PPGEA), Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected]. 5Químico, Mestre, Departamento de Engenharia Ambiental, Fundação Universidade Regional de Blumenau (FURB), Rua São Paulo, n° 3250, Itoupava Norte, Blumenau-SC, Brasil. [email protected].     1 RESUMO   O objetivo do estudo foi comparar dados do conteúdo de água do solo obtidos por técnicas laboratoriais (Extrator de Pressão de Richards) e por técnicas de determinação em campo (tensiômetros e TDR) em diferentes usos do solo. Os usos do solo estudados foram: agricultura, floresta nativa (Bioma Mata Atlântica), reflorestamento e pastagem. O conteúdo de água no solo determinado pelas curvas de retenção foi menor na camada superficial do solo, com aumento gradativo em relação a profundidade. Com o TDR, os valores do conteúdo de água alternaram nas profundidades e para os diferentes usos. Este resultado foi associado ao fato de que curvas de retenção ficam restritas a pressões máximas de 916 kPa em períodos de restrição hídrica. O método de Richards subestimou os valores de umidade nas áreas de agricultura, pastagem, reflorestamento, e superestimou os valores na área de floresta. O método de Richards também apresentou ineficiência na saturação (θs) das amostras e no equilíbrio hidráulico da umidade residual (θr). Apesar de alguns valores terem sido subestimados, a regressão linear do conteúdo médio de água no perfil do solo obtido pelos diferentes métodos apresentou correlação positiva para as áreas de agricultura e floresta e baixa correlação para as áreas de pastagem e reflorestamento. Estes resultados foram confirmados na regressão linear da variação diária de armazenamento de água ao longo do perfil.   Palavras-chave: Reflectometria no Domínio do Tempo (TDR), Richards, tensiometria.     GOTARDO, R.; PINHEIRO, P.; KAUFMANN, V.; PIAZZA, G. A.; TORRES, E. COMPARISON OF WATER RETENTION CURVES OBTAINED IN LABORATORY AND FIELD MEASUREMENTS       2 ABSTRACT   The aim of this study was to compare soil water content data obtained by laboratory techniques (Richards Pressure Extractor) and field measurements (tensiometers and TDR) in different land uses. The land uses analyzed in this study were agriculture, native forest (Atlantic Forest), reforestation and pasture. The soil water content determined by the retention curve was lower in the soil surface with  gradual increase in dept. With TDR, the values of water content​ ​alternated in depths and for different uses. This result was associated to the fact that retention curves are restricted to maximum pressures of 916 kPa in periods of water restriction. Richards’ method underestimated moisture values ​​in agriculture, pasture and reforestation areas, and overestimated these values ​​in  forest area.  Richards’ method also showed inefficiency to calculate  saturation of  samples (θs) and hydraulic balance of residual moisture (θr). Despite the underestimation, the linear regression of  average water content in the soil profile obtained by these methods showed a positive correlation for agriculture and forestry, and negative to pasture and reforestation. These results were confirmed by the linear regression of daily variation water storage along the profile.   Keywords: Time Domain Reflectometry (TDR), Richards, tensiometers.  

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