Frozen soil has a major effect in many hydrologic processes, and its impacts are difficult to predict. A prime example is flood forecasting during spring snowmelt within the Canadian Prairies. One key driver for the extent of flooding is the antecedent soil moisture and the possibility for water to infiltrate into (partly) frozen soils. Therefore, these situations are crucial for accurate flood prediction at every spring. The main objective of this study was to evaluate the water flow and heat transport within available hydrological models to predict the impact of frozen and partly frozen soil on infiltration and percolation. A standardized data set was developed for water flow and heat transport into (partial) frozen soil by laboratory experiments using fine sand within a one-dimensional (1-D) soil column. A 1-D soil column having a length of 107 cm and diameter of 35.6 cm was built and equipped with insulation to limit heat exchange only through the soil surface. A data logger collected the moisture content and temperature by five FDR sensors which have been installed at a distance of 15 cm from each other. During the experiments, temperature, soil moisture, and percolated water was observed at different freezing conditions (-5°C, -10°C, and -15°C) as well as at thawing conditions when the air temperature was increased to +5°C. Distribution of soil moisture and soil temperature in the soil column was plotted for the experimental data over the freezing and thawing period. As some of the water in the soil begins to freeze, a decrease in water content was observed with a sudden increase in soil temperature near 0°C or slightly below of 0°C. This was, in fact, only a decrease in unfrozen water, not a decrease in total water content and was caused by the latent heat during freezing. Soil temperature showed noticeable differences at the top and the bottom of soil column during the change of state of water. The heat flux at the lower soil column was strongly limited due to iii the overlying soil. Thus, the soil temperature at the lowest sensors stayed in a freezing condition over several days and was not changing the temperature due to the latent heat which was released during the freezing process. Significant variation in soil moisture content was found between the top and the bottom of the soil column at the starting of the thawing period. However, with increasing temperature, the lower depth of the soil column showed higher moisture content as the soil was enriched with moisture with higher transmission rate due to the release of heat by soil particles during the thawing cycle. The soil system did not remain in the isothermal state during the thawing cycle. Although gravitational gradient was mainly responsible for the infiltration rate into the partially frozen soil, the distribution of moisture was greatly influenced by the temperature gradient. Vadose zone modeling using HYDRUS-1D was applied to the data set. Numerical results of the modeling were calibrated using the experimental results. It showed that the newly developed benchmark data set were useful for the validation of numerical models. The use of such a validated freezing and thawing module implemented into larger scale hydrologic models will directly reduce the prediction uncertainty during flood forecasting. Moreover, these benchmark data sets will be useful for the validation of numerical models and for developing scientific knowledge to suggest potential code variations or new code development in numerical models. / February 2017

This study explored the available adfreeze data published in literature and the techniques used to obtain it. Two methods were selected and modified to complete series of adfreeze bond test. A model pile pull-out method consisting of pulling a pile out a large specimen of soil was the first method used. The second method was modified from an interface shearing apparatus developed by Dr. Fakharian and Dr. Evgin at the University of Ottawa in 1996 and allowed preparing, freezing and testing the specimen in place. The material and soil tested for this study were provided by EXP Services Inc. The model pile, a galvanized HSS 114.3 x 8.6 section, is commonly used to install solar panels. Soil was taken from a future solar farm site in proximity to Cornwall, Ontario. The study had for objective to develop a low cost adfreeze laboratory testing method. Limitations of the technics and apparatus used were observed. While the results of a model pile pull-out test compared to previous data publish by Parameswaran (1978), the interface shear series of test presented more limitations. The interface shearing method has been previously study by Ladanyi and Thériault (1990). Issues with the interface shear method due to the water content of the soil as well as the range of normal stress applied to the specimen both during testing and freezing. The data obtained was inconclusive and the method will be studied in future research program. This studied approach the adfreeze testing with new improvement. The main contribution of this study is the data obtained by measuring and observing adfreeze of ice poor sand with varying water content. The measurements allowed to study the effect that increasing water content has on the interface bond strength. The modifications made to interface shear apparatus are also major new contribution provided by this research. The apparatus was converted in a small freezer chamber using insulation panel and vortex tubes. Which was used to freeze the specimen in the testing chamber and testing adfreeze in place without handling the shear box arrangement.

Meltwater reaching the base of the snowpack may either infiltrate the underlying stratum, run off, or refreeze, forming a basal ice layer. Frozen ground underneath a melting snowpack constrains infiltration promoting runoff and refreezing. Compositional changes in chemistry take place for each of these flowpaths as a result of phase change, contact between meltwater and soil, and mixing between meltwater and soil water. Meltwater ion concentrations and infiltration rate into frozen soils both decline rapidly as snowmelt progresses. Their temporal association is highly non-linear and the covariance must be compensated for in order to use time-averaged values to calculate chemical infiltration over a melt event. This temporal covariance is termed �enhanced infiltration� and represents the additional ion load that infiltrates due to the timing of high meltwater ion concentration and infiltration rate. Both theoretical and experimental assessments of the impact of enhanced infiltration showed that it causes a greater ion load to infiltrate leading to relative dilute runoff water. Sensitivity analysis showed that the magnitude of enhanced infiltration is governed by initial snow water equivalent, average melt rate, and meltwater ion concentration factor. Based on alterations in water chemistry due to various effects, including enhanced infiltration, three major flowpaths could be distinguished: overland flow, organic interflow, and mineral interflow. Laboratory experiments were carried out in a temperature-controlled environment to identify compositional changes in water from these flowpaths. Samples of meltwater, runoff, and interflow were filtered and analyzed for major anions and cations. Chemical signatures for each flowpath were determined by normalizing runoff and interflow concentrations using meltwater concentrations. Results showed that changes in ion concentrations were most significant for H⁺, NO₃^�, NH₄⁺, Mg²⁺, and Ca²⁺. Repeated flushes of meltwater through each interflowpath caused a washout of ions. In the field, samples of soil water and ponding water were collected daily from a Rocky Mountain hillslope during snowmelt. Their normalized chemical compositions were compared to the laboratory-identified signatures to evaluate the flowpath. The majority of the flowpaths sampled had chemical signatures, which indicated mineral interflow, only 10% showed unmixed organic interflow.

Meltwater reaching the base of the snowpack may either infiltrate the underlying stratum, run off, or refreeze, forming a basal ice layer. Frozen ground underneath a melting snowpack constrains infiltration promoting runoff and refreezing. Compositional changes in chemistry take place for each of these flowpaths as a result of phase change, contact between meltwater and soil, and mixing between meltwater and soil water. Meltwater ion concentrations and infiltration rate into frozen soils both decline rapidly as snowmelt progresses. Their temporal association is highly non-linear and the covariance must be compensated for in order to use time-averaged values to calculate chemical infiltration over a melt event. This temporal covariance is termed �enhanced infiltration� and represents the additional ion load that infiltrates due to the timing of high meltwater ion concentration and infiltration rate. Both theoretical and experimental assessments of the impact of enhanced infiltration showed that it causes a greater ion load to infiltrate leading to relative dilute runoff water. Sensitivity analysis showed that the magnitude of enhanced infiltration is governed by initial snow water equivalent, average melt rate, and meltwater ion concentration factor. Based on alterations in water chemistry due to various effects, including enhanced infiltration, three major flowpaths could be distinguished: overland flow, organic interflow, and mineral interflow. Laboratory experiments were carried out in a temperature-controlled environment to identify compositional changes in water from these flowpaths. Samples of meltwater, runoff, and interflow were filtered and analyzed for major anions and cations. Chemical signatures for each flowpath were determined by normalizing runoff and interflow concentrations using meltwater concentrations. Results showed that changes in ion concentrations were most significant for H⁺, NO₃^�, NH₄⁺, Mg²⁺, and Ca²⁺. Repeated flushes of meltwater through each interflowpath caused a washout of ions. In the field, samples of soil water and ponding water were collected daily from a Rocky Mountain hillslope during snowmelt. Their normalized chemical compositions were compared to the laboratory-identified signatures to evaluate the flowpath. The majority of the flowpaths sampled had chemical signatures, which indicated mineral interflow, only 10% showed unmixed organic interflow.

No description available.

Meltwater reaching the base of the snowpack may either infiltrate the underlying stratum, run off, or refreeze, forming a basal ice layer. Frozen ground underneath a melting snowpack constrains infiltration promoting runoff and refreezing. Compositional changes in chemistry take place for each of these flowpaths as a result of phase change, contact between meltwater and soil, and mixing between meltwater and soil water. Meltwater ion concentrations and infiltration rate into frozen soils both decline rapidly as snowmelt progresses. Their temporal association is highly non-linear and the covariance must be compensated for in order to use time-averaged values to calculate chemical infiltration over a melt event. This temporal covariance is termed �enhanced infiltration� and represents the additional ion load that infiltrates due to the timing of high meltwater ion concentration and infiltration rate. Both theoretical and experimental assessments of the impact of enhanced infiltration showed that it causes a greater ion load to infiltrate leading to relative dilute runoff water. Sensitivity analysis showed that the magnitude of enhanced infiltration is governed by initial snow water equivalent, average melt rate, and meltwater ion concentration factor. Based on alterations in water chemistry due to various effects, including enhanced infiltration, three major flowpaths could be distinguished: overland flow, organic interflow, and mineral interflow. Laboratory experiments were carried out in a temperature-controlled environment to identify compositional changes in water from these flowpaths. Samples of meltwater, runoff, and interflow were filtered and analyzed for major anions and cations. Chemical signatures for each flowpath were determined by normalizing runoff and interflow concentrations using meltwater concentrations. Results showed that changes in ion concentrations were most significant for H+, NO3�, NH4+, Mg2+, and Ca2+. Repeated flushes of meltwater through each interflowpath caused a washout of ions. In the field, samples of soil water and ponding water were collected daily from a Rocky Mountain hillslope during snowmelt. Their normalized chemical compositions were compared to the laboratory-identified signatures to evaluate the flowpath. The majority of the flowpaths sampled had chemical signatures, which indicated mineral interflow, only 10% showed unmixed organic interflow.

This thesis deals with the study of soils freezing in terms of phase change of water contained in the soil strata on green roofs. The aim of this work is to verify the effect of phase transformation of water on the course of temperature oscillation. First described the basic characteristics of soils generally, and subsequently described processes occurring during phase transformation of water in the soil and has been carried out experimental verification of the effect of moisture in the soil on the course of temperature oscillation. In the overall evaluation of the work, an analysis of the effect of phase change water in soil on the course of temperature oscillation and the resulting conclusion of work.

Soil freezing/thawing is of importance in the transport of water, heat and solute, with coupled effects. Due to complexity in soil freezing/thawing, uncertainty could be influential in both experimentation and simulation work in frozen soils. Solute and water in frozen soil could reduce the freezing point, resulting in uncertainty in simulation water, heat and solute processes as well as in estimation of frozen soil evaporation. High salinity and groundwater level could result in high soil evaporation during wintertime. Seasonal courses in energy and water balance on surface have shown to be influential to soil water and heat dynamics, as well as in salt accumulation during wintertime. Water and solute accumulated during freezing period resulted in high evaporation during thawing period and enhanced surface salinization. Diurnal changes in surface energy partitioning resulted in significant cycle of freezing/thawing as well as in evaporation/condensation in surface layer, which could in turn affect atmosphere. Uncertainties in experiments and simulations were detectable in investigation of seasonally frozen soils with limited methods and simplified representations of reality in two agricultural fields in northern China. Soil water and solute contents have shown to be more uncertain than soil temperatures in both measurements and simulations. The combination of experiments with process-based model (CoupModel) has proven to be useful in understanding freezing/thawing processes and in identification of uncertainty, when Monte-Carlo based methods were used for evaluation of simulations. Correlations between parameters and model performance indices needed to be taken into account carefully in calibration of the process-based model. Parameters related to soil hydraulic processes and surface energy processes were more sensitive when using different datasets for calibration. In using multiple model performance indicators for multi-objective evaluation, the trade-offs between them have shown to be a source of uncertainty in calibration. More proper representations of the reality in model (e.g., soil hydraulic and thermal properties) and more detailed measurements (e.g., soil liquid water content and solute concentration) as input would be efficient in reducing uncertainty. Relationships between groundwater, soil and climate change would be of high interest for better understanding of cold regions water and energy balance. / 土壤冻融过程对于水热及溶质的运移具有十分重要的影响，并对于寒旱区水文过程的研究有着深远意义。在冻土中，溶质的存在导致冰点降低，改变土壤冻融规律，进而影响冻融土壤水热运移。冻融土壤地表水分及能量平衡的季节性变化规律对土壤水热运移及盐分的积累影响较大。同时，土壤冻融的水热平衡日变化规律对表层土壤水热过程影响较为强烈，并进而影响地表的气象变化。试验研究表明，高溶质含量及浅埋深地下水条件为地表的蒸发提供了便利条件，因为高溶质含量土壤冰点降低，同一负温条件下的液态含水量增大，为蒸发提供了可利用水分；而浅埋深地下水对冻融期水盐的表聚提供的方便，进而有助于融化期地表水分的大量蒸发及下层土层水分的大量向上补给。例如，当地下水初始埋深设置在1.5 m时，对于初始含盐量分别为0.2%，0.4% 和0.6% g/g的冻融试验组，冻融期累积蒸发量分别为51.0，96.6和114.0 mm。同样的增加趋势在其它初始地下水埋深设置试验组里也被验证，且初始地下水埋深越浅，累积蒸发量也越大。对于利用有限的试验数据及简化的数值模型对冻融土壤水热及溶质研究，由于试验及模型的不确定性，会造成结果的不确定性。而通过利用不确定性分析的方法将试验结果与数值模型结合起来可以较好地理解土壤冻融过程及处理不确定性，并进而为改进试验方法及完善数值模型提供参考。模型不确定分析结果表明，模型参数之间，及参数与模型模拟效果评价因子之间存在较强的相关性，会造成模拟结果的不确定性。而不同模拟方法的结果对比表明，在进行冻融土壤水热及溶质模拟时，建立更为完善的考虑更为详细的过程的数值模型可以提高模型的模拟效率，减小模拟结果的不确定性。同时，试验数据的不确定性也显示出了对模拟结果的显著影响。精确的试验数据及更为科学的试验方法有助于减少模拟结果的不确定性。在减少模拟结果的不确定性上也有重要作用。同时，由于寒区水文过程的复杂性及在气候变化过程中的重要性，有必要进一步开展寒区地下水，土壤水热盐与气候变化关系的研究，以便于制定更为合理的寒区水资源管理策略。 / Frysning och tining är av betydelse för kopplade flöden av vatten, värme och lösta ämnen i mark. Komplexiteten i sambanden mellan lösta ämnen, ofruset vatten och fryspunkten skapar en osäkerhet vid simuleringar av processer för både vatten, värme och lösta ämnen i marken samt för avdunstningen från markytan. Årtidsberoende mönster i energi- och vattenbalansen för markytan påverkar värme- och vattendynamiken i marken samt ackumulering av salter under vintern. Dygnsvariationer i energibalansens uppdelning vid markytan ger upphov till frysning/tining samt avdunstning och kondensation i ytliga lager som har återkopplingar också till tillstånden i atmosfärens ytskikt. Osäkerheter i både experiment och i simuleringar spårades i undersökningar av säsongstyrd frysning av mark i två provincer av norra Kina. Begräningar i metodik och förenklingar av naturens komplexitet kunde klargöras. Kombinationen av experiment och processbaserad modellering med CoupModel var lyckosam för föreståelsen av frysning/tining och kunde klargöra osäkerhet med hjälp av Monte Carlo teknik. Korrelation mellan parametrar och prestanda hos modellen var en viktig del av kalibreringsproceduren. En förbättrad processbeskrivning av marken och minskad parameterosäkerhet kan erhållas om också mer detaljerade mätningar inbegrips i framtida studier. Sambanden mellan grundvatten, mark och klimatförändringar är av största intresse för en bättre kunna beskriva kalla regioners vatten- och energibalanser. / <p>QC 20160329</p>

In der vorliegenden Arbeit wurden Doppelringinfiltrationsexperimente an teilweise gefro­renen Böden durchgeführt. Diese Experimente wurden anschließend mit den zwei computer­ge­stützten Modellen, Erosion 3D / Winter und COUP, nachgestellt, um die Frage zu beantworten, ob es möglich ist, die Infiltration in teilweise gefrorene Böden vorherzusagen. Die Doppelringinfiltrationsexperimente wurden auf einem ackerbaulich genutzten Lehm­boden mit geringer Lagerungsdichte und Bodenfeuchten im Bereich der Feld­kapa­zität, an der nördlichen Grenze des hydrologischen Untersuchungsgebietes „Schäfertal“ durch­ge­führt. Drei Experimente erfolgten bei teilweise gefrorenen und ein Experiment bei unge­frorenem Boden. Bei diesen Experimenten wurde herausgefunden, dass die Endinfiltrationsrate des gefro­renen Bodens mit 7·10-5 m/s gleich der Endinfiltrationsrate des ungefrorenen Bodens war. Während bei dem Infiltrationsexperiment mit ungefrorenem Boden die Endinfiltrations­rate bereits nach 10 bis 20 min erreicht war, wurden bei den Experimenten mit gefrorenen Böden aufgrund der zusätzlichen Sättigung des kryoturbativen Sekundärporenvolumens mehr Zeit benötigt. Zu den im Boden ablaufenden Prozessen bei Zugabe von Infiltrationswasser (Tem­pe­ratur­veränderung, Gefrier- und Auftauprozesse, Veränderung der Porosität) besteht noch Klärungsbedarf. Der für die Modellierung wichtige Eingabeparameter der Anfangsbodenfeuchte konnte bei winterlichen Bedingungen nicht genau bestimmt werden. Gravimetrische Boden­feuchtebestimmungen liefern aufgrund des Eintrags von zusätzlichen Eis- und Schnee-Wasser zu hohe Werte. TDR- und Watermark-Messungen unterschätzen hingegen die Bodenfeuchten, weil sie nur den Anteil des flüssigen Wassers berücksichtigen. Mit Erosion 3D / Winter konnten die Ergebnisse der Infiltrationsexperimente, unter der Voraussetzung, dass die effektive gesättigte hydraulische Leitfähigkeit des ungefrorenen Bodens exakt bekannt war, sehr gut nachgestellt werden. Eine Modellierung der Infiltration in einen teilweise gefrorenen Boden ist damit, zumindest für den untersuchten Boden und die betrachteten meteorologischen Bedingungen, möglich. Das COUP - Modell lieferte dagegen völlig andere Ergebnisse, weil von einem Ein­frieren des infiltrierten Wassers bei negativen Temperaturen ausgegangen wird. Eine Verbesserung der Infiltrationsbeschreibungen könnte hier wahrscheinlich durch die Vorgabe einer größeren Anzahl von Eingabeparametern, die die natürliche Situation besser repräsentieren als die für die Modellierung verwendeten Daten, erfolgen.

In der vorliegenden Arbeit wurden Doppelringinfiltrationsexperimente an teilweise gefro­renen Böden durchgeführt. Diese Experimente wurden anschließend mit den zwei computer­ge­stützten Modellen, Erosion 3D / Winter und COUP, nachgestellt, um die Frage zu beantworten, ob es möglich ist, die Infiltration in teilweise gefrorene Böden vorherzusagen. Die Doppelringinfiltrationsexperimente wurden auf einem ackerbaulich genutzten Lehm­boden mit geringer Lagerungsdichte und Bodenfeuchten im Bereich der Feld­kapa­zität, an der nördlichen Grenze des hydrologischen Untersuchungsgebietes „Schäfertal“ durch­ge­führt. Drei Experimente erfolgten bei teilweise gefrorenen und ein Experiment bei unge­frorenem Boden. Bei diesen Experimenten wurde herausgefunden, dass die Endinfiltrationsrate des gefro­renen Bodens mit 7·10-5 m/s gleich der Endinfiltrationsrate des ungefrorenen Bodens war. Während bei dem Infiltrationsexperiment mit ungefrorenem Boden die Endinfiltrations­rate bereits nach 10 bis 20 min erreicht war, wurden bei den Experimenten mit gefrorenen Böden aufgrund der zusätzlichen Sättigung des kryoturbativen Sekundärporenvolumens mehr Zeit benötigt. Zu den im Boden ablaufenden Prozessen bei Zugabe von Infiltrationswasser (Tem­pe­ratur­veränderung, Gefrier- und Auftauprozesse, Veränderung der Porosität) besteht noch Klärungsbedarf. Der für die Modellierung wichtige Eingabeparameter der Anfangsbodenfeuchte konnte bei winterlichen Bedingungen nicht genau bestimmt werden. Gravimetrische Boden­feuchtebestimmungen liefern aufgrund des Eintrags von zusätzlichen Eis- und Schnee-Wasser zu hohe Werte. TDR- und Watermark-Messungen unterschätzen hingegen die Bodenfeuchten, weil sie nur den Anteil des flüssigen Wassers berücksichtigen. Mit Erosion 3D / Winter konnten die Ergebnisse der Infiltrationsexperimente, unter der Voraussetzung, dass die effektive gesättigte hydraulische Leitfähigkeit des ungefrorenen Bodens exakt bekannt war, sehr gut nachgestellt werden. Eine Modellierung der Infiltration in einen teilweise gefrorenen Boden ist damit, zumindest für den untersuchten Boden und die betrachteten meteorologischen Bedingungen, möglich. Das COUP - Modell lieferte dagegen völlig andere Ergebnisse, weil von einem Ein­frieren des infiltrierten Wassers bei negativen Temperaturen ausgegangen wird. Eine Verbesserung der Infiltrationsbeschreibungen könnte hier wahrscheinlich durch die Vorgabe einer größeren Anzahl von Eingabeparametern, die die natürliche Situation besser repräsentieren als die für die Modellierung verwendeten Daten, erfolgen.