The thesis numerically models and investigates the effect of a variable water table on the soil moisture content. The modelling is done using COMSOL and Richards' equation. The temporal variation plots can be used to find the capillarity of the soil and its impact on other phenomenon such as vapor intrusion and infiltration.

<p>Present master of science thesis has been carried out at the Swedish Road Administration consulting services (Vägverket Konsult) in Karlstad. The purpose of the study is to investigate how well the calculated drawdown of the groundwater table predicts the actual drawdown when the road and railway gates at the studied sites are built. For this purpose the groundwater levels at the three bridges were measured during 6 months. The bridges in question are two railway bridges situated in Ölme and Ulvåker and one road bridge crossing a pedestrian and cycling path in Lidköping.</p><p>In Ölme the calculated area of influence was smaller than the measured one. It differed up to 30 meters, i.e. 80 %.</p><p>In Lidköping the calculated area of influence agreed well with the measured one, but the groundwater level that the calculations were made from was more than one meter too low.</p><p>In Ulvåker the measured groundwater levels were influenced by other factors and no conclusions could be drawn.</p><p>When calculating how the groundwater level is affected from road and railway bridge constructions it is important to make sure to measure the groundwater level before the construction is made so that the unaffected level is known. Moreover the radius of the well should be set to a value less than 0.5 meters. It is also important that the conductivity is investigated thoroughly especially for confined aquifers. When measuring groundwater levels the examiner must make sure to plan the distances and depths of the piezometer wells, when to perform the measurements and how to protect the water in the wells from freezing.</p> / <p>Detta examensarbete är utfört på Vägverket Konsult i Karlstad. Syftet med arbetet är att med några exempel undersöka hur väl den beräknade permanenta grundvattensänkningen överensstämmer med den verkliga grundvattensänkning som görs vid byggen av vägportar. Arbetet utfördes genom att under 6 månader mäta grundvattennivåerna vid tre vägportar. De undersökta portarna är en väg – järnvägport i Ölme, en gång- och cykelväg – vägport i Lidköping och en väg – järnvägport i Ulvåker.</p><p>I Ölme framkom att den permanenta grundvattensänkningen har ett större influensområde än den beräknade. Differensen uppgick som mest till 30m vilket motsvarar en avvikelse på ca 80 %.</p><p>I Lidköping överensstämmer beräkningen av influensradierna väl med de uppmätta, medan grundvattennivån som beräkningarna gjordes från ligger drygt en meter för lågt.</p><p>I Ulvåker är den uppmätta avsänkningen påverkad av yttre faktorer och därför kan inga slutsatser dras.</p><p>Vid grundvattensänkningsberäkningar är det viktigt att den opåverkade grundvattennivån är känd, att brunnsradien sätts till ett tal mindre än 0,5 meter och att bestämningen av konduktiviteten är extra noga vid sluten akvifer. När grundvattennivåerna ska mätas bör avstånd och höjdnivå på grundvattenrören bestämmas noga, mätningarna utföras kontinuerligt under en längre tid och eventuell tillsats av frostskydd i grundvattenrören tänkas igenom.</p>

Present master of science thesis has been carried out at the Swedish Road Administration consulting services (Vägverket Konsult) in Karlstad. The purpose of the study is to investigate how well the calculated drawdown of the groundwater table predicts the actual drawdown when the road and railway gates at the studied sites are built. For this purpose the groundwater levels at the three bridges were measured during 6 months. The bridges in question are two railway bridges situated in Ölme and Ulvåker and one road bridge crossing a pedestrian and cycling path in Lidköping. In Ölme the calculated area of influence was smaller than the measured one. It differed up to 30 meters, i.e. 80 %. In Lidköping the calculated area of influence agreed well with the measured one, but the groundwater level that the calculations were made from was more than one meter too low. In Ulvåker the measured groundwater levels were influenced by other factors and no conclusions could be drawn. When calculating how the groundwater level is affected from road and railway bridge constructions it is important to make sure to measure the groundwater level before the construction is made so that the unaffected level is known. Moreover the radius of the well should be set to a value less than 0.5 meters. It is also important that the conductivity is investigated thoroughly especially for confined aquifers. When measuring groundwater levels the examiner must make sure to plan the distances and depths of the piezometer wells, when to perform the measurements and how to protect the water in the wells from freezing. / Detta examensarbete är utfört på Vägverket Konsult i Karlstad. Syftet med arbetet är att med några exempel undersöka hur väl den beräknade permanenta grundvattensänkningen överensstämmer med den verkliga grundvattensänkning som görs vid byggen av vägportar. Arbetet utfördes genom att under 6 månader mäta grundvattennivåerna vid tre vägportar. De undersökta portarna är en väg – järnvägport i Ölme, en gång- och cykelväg – vägport i Lidköping och en väg – järnvägport i Ulvåker. I Ölme framkom att den permanenta grundvattensänkningen har ett större influensområde än den beräknade. Differensen uppgick som mest till 30m vilket motsvarar en avvikelse på ca 80 %. I Lidköping överensstämmer beräkningen av influensradierna väl med de uppmätta, medan grundvattennivån som beräkningarna gjordes från ligger drygt en meter för lågt. I Ulvåker är den uppmätta avsänkningen påverkad av yttre faktorer och därför kan inga slutsatser dras. Vid grundvattensänkningsberäkningar är det viktigt att den opåverkade grundvattennivån är känd, att brunnsradien sätts till ett tal mindre än 0,5 meter och att bestämningen av konduktiviteten är extra noga vid sluten akvifer. När grundvattennivåerna ska mätas bör avstånd och höjdnivå på grundvattenrören bestämmas noga, mätningarna utföras kontinuerligt under en längre tid och eventuell tillsats av frostskydd i grundvattenrören tänkas igenom.

No / This paper aims to investigate experimentally the effects of circulating coolant flow rate, groundwater table fluctuations, infiltration of rainwater, on the amount of thermal energy that can be recovered from the near surface soil layers. A comprehensive experimental investigation was carried out on a fully equipped tank filled with sand. A heat collector panel was embedded horizontally at the mid-height of the tank. Measurements of the temperature at various points on the heat collector panel, adjacent soil, inlet and outlet were continuously monitored and recorded. After reaching a steady state, it was observed that increasing water saturation in the adjacent soil leads to a substantial increase on the amount of heat recovered. A model was proposed for the estimation of temperature along the heat collector panel based on steady state conditions. It accounted for thermal resistance between pipes and the variability of water saturation in the adjacent soils. This model showed good agreement with the data. Whilst increasing the flow rate of the circulating fluid within the panel did not cause noticeable improvement on the amount of heat energy that can be harnessed within the laminar flow regime commonly found in ground source heat panels. Infiltration of rainwater would cause a temporary enhancement on the amount of extracted heat. Measurement of the sand thermal conductivity during a cycle of drying and wetting indicates that the thermal conductivity is primarily dependent upon the degree of water saturation and secondary on the flow path.

yes / This paper presents field measurements in which dye solute was injected into coastal sand to investigate contaminant advection in intertidal beach sand. The measurements show the pathways of a contaminated plume in the unsaturated zone during both the flood and ebb tides. A prescribed amount of dye tracer solution was directly injected through the topsoil, with average porosity 0.3521±0.01, at predetermined locations of the River Mersey’s outer estuarial beach during ebb-tide. The injected dye was monitored, sampled and photographed over several tidal cycles. The distinctive features of the plume (full two dimensional cross-sections), sediments and water-table depth were sampled in-situ, close to the injection point (differing from previous contaminant monitoring tests in aquifers). The advective movement is attributed to tidal impact which is different from contaminant transport in aquifers. The experimental results show that plumes have significantly large spatial variability, diverging upwards and converging downwards, with a conical geometric shape which is different from the usual spherical/elliptical shape reported in literature. The mean vertical motion of the plume reaches three times the top-width within ten tidal cycles, exceeding the narrow bottom-width by a factor of order 2. The observed transport features of the plume within the beach sand have significant relevance to saltwater intrusion, surface water and groundwater quality. The field observations are unique and can serve as a valuable benchmark database for relevant numerical studies. / China Ministry of Science and Technology 973 program (2014CB745001), Special Program of future development in Shenzhen (201411201645511650) and Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment（ZDSY20130402163735964).

In this study, The Beach Dewatering System, a relatively recent technology to combat beach erosion, which is proposed as a practical alternative to more traditional shoreline stabilization methods, is investigated and an informative overview on the genesis, development and recent use of this technique is provided. On the basis of the link existing between the elevation of beach groundwater and erosional or accretionary trends at the beach face, a numerical model that simulates groundwater flow in a coastal aquifer under beach drainage is presented. In this model, the seaward boundary of the domain is considered to be tidally fluctuating in a large scale to represent the occurrence of seepage face significantly. The unsteady groundwater flow equation is solved numerically using the method of finite differences. The results clearly showed that the water table being lowered caused the reduction of the seepage face which is the main aim of Beach Dewatering projects. The positional design parameters, i.e. horizontal and vertical location of the drain, are also investigated by utilizing an efficiency index. It is observed that the system efficiency decreased as the drain is shifted landward. The results also indicated that, the efficiency slightly increased with the vertical drain elevation.

L’objectif général de cette thèse était d’améliorer l’utilisation des éléments de diagnostic des sites pollués par des hydrocarbures légers. En particulier, il s’agissait : • De valider la méthode d’estimation de la mobilité de l’huile dans le sol, en milieu hétérogène, appelée bail-down test. Et de définir quelle méthode d’interprétation est la plus adaptée. • Comprendre l’impact des variations de hauteur de nappe sur l’épaisseur d’huile mesurée dans les puits de surveillance et sur la mobilité de l’huile. Dans un premier temps, des simulations de bail-down tests ont été réalisées en laboratoire, sur un pilote radial, remplie d’une matrice homogène. Puis, un grand nombre de tests réalisés sur un terrain d’étude, a été interprété. Ces travaux ont permis de confirmer la validité des bail-down tests pour estimer la mobilité de l’huile dans le milieu. L’hypothèse principale pour expliquer la validité de ces tests, alors que les hypothèses théoriques ne sont à priori pas respectées lors des essais, réside dans la faible mobilité de l’huile liée à une viscosité élevée. Dans un deuxième temps, l’impact des variations de nappes a été suivi par des mesures manuelles et automatiques sur le terrain d’étude, pendant plusieurs mois. Ce suivi a permis de décrire de manière précise cet impact, qui est différent pour un hydrocarbure en nappe libre, ou en milieu confiné. Par ailleurs, un modèle a été développé et testé pour simuler les variations d’épaisseur d’huile en fonction des hauteurs de nappe. Ce modèle permet d’estimer l’épaisseur et la position de l’huile dans la formation, ainsi que sa conductivité hydraulique. Les conclusions de cette étude apportent des éléments importants pour améliorer les phases d’investigation de site pollués par des hydrocarbures légers, et pour optimiser l’utilisation des données collectées. Enfin, confirmant l’impact significatif des variations de nappe sur les épaisseurs d’huile dans les puits et en montrant la validité des bail-down tests pour estimer la mobilité de l’huile, cette étude montre la nécessité de baser le dimensionnement des réseaux d’extraction des hydrocarbures, non pas sur l’épaisseur, mais sur la mobilité du produit. / The overall objective of this thesis was to improve the use of investigation data from contaminated site with light hydrocarbons. In particular, this work focused on: • To confirm the validity of the method to estimate the oil mobility in the formation, for heterogeneous conditions, called bail-down test. And, to define which interpretation method is the most relevant. • To understand the impact of the groundwater table variations on the oil thickness in the monitoring wells, and on its mobility. First, bail-down test simulations were performed at laboratory scale, on a radial pilot, filled with homogeneous sand. Then, a significant number of tests were performed on a studied site and interpreted. This work allowed to confirm the bail-down test validity for estimating the oil mobility in the formation. The key assumption to explain why these tests are valid whereas some of the assumptions and boundary conditions are not met during the tests, is based on the low mobility of the oil due to its viscosity. Secondly, the impact of the groundwater table variations has been manually and automatically measured on the studied site, during months. These measurements allowed to describe in detail the impact, which is different between confined and non-confined oil conditions. In addition, a model has been proposed and tested to simulate oil thickness depending on groundwater table level. This model allowed to estimate the thickness and the position of the oil in the formation, and its hydraulic conductivity. Overall, this study gives key elements to improve the investigation phase of site contaminated with light hydrocarbons, and to optimize the use of the collected data. Last, confirming the significant impact of the groundwater table fluctuation on the oil thickness and the validation of the bail-down test to estimate the oil mobility, this study shows the need to consider the oil mobility rather than the oil thickness for designing an oil recovery project.