The Atascadero Subbasin, located on the central coast of California, is a small, hydraulically separated sub-region of the Paso Robles Groundwater Basin. Three local cities operate approximately 40 wells to pump the Subbasin for their entire water supply needs. Past studies have questioned sustainability of the Subbasin as the combined pumping rate by the three cities is nearing the perennial yield of the Subbasin. The studies have been inconclusive as some areas of the Subbasin have seen increases in water table elevation thus questioning the assessment that consumption is nearing perennial yield. The objective of this research was to perform a water balance study for the aquifer and examine sustainability of the Subbasin. Surface water and groundwater models were developed to investigate the interaction between the Salinas River Alluvium Soils and the deeper Paso Robles Formation based on pumping from different shallow and deep wells. Surface water hydrology of the Subbasin was studied using HEC-HMS, and Visual MODFLOW was used to model the aquifer. Both HEC-HMS and Visual MODFLOW was calibrated to improve simulation accuracy. HEC-HMS was used to quantify natural recharge to the aquifer and to simulate streamflow and water level for the Salinas River. HEC-GeoHMS was used to delineate the watershed, create sub-watersheds and channel networks, and to extract sub-watershed inputs that were used to build HEC-HMS from geospatial data including land use, soil and topography data. Different hydrogeologic layers were defined to represent the alluvium and deeper soils. Results show that currently the Atascadero Subbasin does not appear to be in overdraft as shallow groundwater wells pump Salinas River underflow and the alluvium appears to be providing some recharge to the deeper aquifer. These findings would provide municipal and water managers better understanding of where their water comes from, the effects of their pumping, and could help with developing sustainable management strategies for the Subbasin.

Sampling of an emplaced creosote source installed below the water table at CFB Borden was conducted over a period of ten years, with over nine thousand samples taken from approximately 250 multilevel samplers. This extensive dataset was used in several attempts to model the multi-chemical plumes emanating from this emplaced source, and to further understand the chemical and biological processes affecting these plumes and their natural attenuation. An aerobic microcosm study of naphthalene, 1-methylnaphthalene and acenaphthene was conducted in order to determine the possibility of interactions between these three chemicals. All three chemicals degraded within the eight days of the study, and the degradation of naphthalene and 1-methylnaphthalene was not affected by the presence of any of the three chemicals studied. Acenaphthene degraded more quickly when naphthalene was present in the microcosm. The programs Visual MODFLOW and RT3D were used to model the transport and degradation of naphthalene at CFB Borden. Both a first order rate reaction module and a multiple electron acceptor reaction module were used, and contaminant mass was introduced to the model through a fence of observed concentrations. Good results were found at early time with the multiple electron acceptor reaction package, however at late time the model did not match to observations. The program BIONAPL/3D was used in a similar attempt to model the transport and degradation of naphthalene. Naphthalene mass was introduced to the model through a fence of observed concentrations, and multiple electron acceptors were used to degrade this chemical. Results were good at early time, but at late time the model did not match observations. BIONAPL was then used to simulate the dissolution of the original source NAPL. Several chemicals of interest were examined: naphthalene, m-xylene, 1-methylnaphthalene and acenaphthene. Naphthalene and m-xylene dissolved from the source at rates similar to observations, however the dissolution of 1-methylnaphthalene and acenaphthene was not as well modeled. As with the Visual MODFLOW model, the BIONAPL model which best matched observations generally worked well at early times, but did not at late times. The models were not able to successfully simulate many processes that occur in the field, such as chemical and biological interactions and NAPL source dissolution. Mismatches between the models and observations are likely due to these reasons. It may be that we do not fully understand these processes, so we are unable to model them.

Sampling of an emplaced creosote source installed below the water table at CFB Borden was conducted over a period of ten years, with over nine thousand samples taken from approximately 250 multilevel samplers. This extensive dataset was used in several attempts to model the multi-chemical plumes emanating from this emplaced source, and to further understand the chemical and biological processes affecting these plumes and their natural attenuation. An aerobic microcosm study of naphthalene, 1-methylnaphthalene and acenaphthene was conducted in order to determine the possibility of interactions between these three chemicals. All three chemicals degraded within the eight days of the study, and the degradation of naphthalene and 1-methylnaphthalene was not affected by the presence of any of the three chemicals studied. Acenaphthene degraded more quickly when naphthalene was present in the microcosm. The programs Visual MODFLOW and RT3D were used to model the transport and degradation of naphthalene at CFB Borden. Both a first order rate reaction module and a multiple electron acceptor reaction module were used, and contaminant mass was introduced to the model through a fence of observed concentrations. Good results were found at early time with the multiple electron acceptor reaction package, however at late time the model did not match to observations. The program BIONAPL/3D was used in a similar attempt to model the transport and degradation of naphthalene. Naphthalene mass was introduced to the model through a fence of observed concentrations, and multiple electron acceptors were used to degrade this chemical. Results were good at early time, but at late time the model did not match observations. BIONAPL was then used to simulate the dissolution of the original source NAPL. Several chemicals of interest were examined: naphthalene, m-xylene, 1-methylnaphthalene and acenaphthene. Naphthalene and m-xylene dissolved from the source at rates similar to observations, however the dissolution of 1-methylnaphthalene and acenaphthene was not as well modeled. As with the Visual MODFLOW model, the BIONAPL model which best matched observations generally worked well at early times, but did not at late times. The models were not able to successfully simulate many processes that occur in the field, such as chemical and biological interactions and NAPL source dissolution. Mismatches between the models and observations are likely due to these reasons. It may be that we do not fully understand these processes, so we are unable to model them.

Grundvattenmodellering av föroreningstransport   – Ett uppdragsanpassat beräkningsverktyg Emil Friberg Målet för detta arbeta var att bygga upp en modell i modelleringsprogrammet MODFLOW för spridning av förorenande ämnen i grundvattnet. Syftet med modellen var att finna en balans mellan den mycket enkla modellen som Naturvårdsverket har satt upp för förorenad mark och en fullskalig platsspecifik modell. Utgångspunkten var att studera litteraturen för att finna lämpliga generella parametrar som beskriver föroreningstransport i grundvattnet. Tre genomförda uppdrag med förorenad mark användes som referenskälla, men även för att evaluera den framtagna modellen. Föroreningarna som förekom i dessa uppdrag och som studerades i detta arbete är bensen, PCE och arsenik. Att finna lämpliga parametrar för beskrivning av transporten visade sig vara ganska enkelt, det finns en god förståelse för vilka faktorer som har betydelse. Däremot var det svårare att finna generella värden till dessa parametrar. Sammanställningar gjorda av Naturvårdsverket var en god källa. Den uppbyggda modellen döptes till ESM. Alla valda parametrar analyserades och modellen känslighetsanalyserades. Resultatet visade att vissa parametrar ger större känslighet än andra. Samtidigt visade analyserna att känsligheten varierar beroende på vilket intervall en viss parameter studeras samt att modellens känslighet även är beroende på värdena på de andra parametrarna. Bland annat visade det sig att dispersion alltid är en känslig parameter inom vissa intervall. Sorption och grundvattenflödets gradient visade sig enbart vara känsliga i vissa fall. ESM jämfördes med analytiska lösningsmetoder, Naturvårdsverkets riktlinjesmodell samt de tre utvalda uppdragen. Resultatet var blandat. I jämförelsen med den enklaste analytiska lösningsmetoden med enbart advektion och dispersion överensstämde inte resultaten . Då även sorption användes blev resultatet mycket bra med en hög överensstämmelse. Det gick inte att jämföra Naturvårdsverkets modell rakt av med ESM då förutsättningarna var ganska skilda. Däremot visade jämförelsen i ett större perspektiv att ESM ger en bättre bild av föroreningsspridningen än vad Naturvårdsverkets riktlinjesmodell ger.  Även jämförelsen mellan ESM och de utvalda uppdragen gav blandat resultat, vissa fall blev resultatet mycket bra medan andra mindre. Generellt gav ESM en bra bild av föroreningssituationen och dess karaktär men den har svårigheter att återspegla verkligheten beträffande uppmätta halter och andra mer specifika parametrar. Slutsatsen blev att ESM kan användas initialt för att få en bild av situationen och att modellen är enkel att förändra men kan inte återspegla alla aspekter på föroreningstransporten. Nyckelord: MODFLOW, MT3DMS, föroreningstransport, PCE, bensen, arsenik, riktvärde för förorenad mark Institutionen för geovetenskaper; luft-, vatten- och landskapslära. Uppsala universitet Villavägen 16, Se-752 36 UPPSALA

Geothermal energy can be extracted from an aquifer, where the groundwater is used as heat exchange medium while heat and cold are stored in the surrounding material in the aquifer and to some extent in the groundwater. Application of aquifer storage for the use of geothermal energy is mainly used in large scale facilities and is limited to sites with suitable aquifers in the form of ridges, sandstone and limestone aquifers. Löwenströmska hospital in the municipality of Upplands Väsby, north of Stockholm, is located nearby the northern part of the Stockholm esker. This means that it can be profitable and environmentally beneficial for the hospital to examine the possibilities of aquifer storage in the esker material next to its property. The purpose of this master thesis has been to investigate if geothermal energy storage with a seasonal storage of heat and cold can be applied within Löwenströmska hospital’s property area using groundwater modeling. A hydraulic groundwater model was constructed in MODFLOW based on a simplified conceptual model of the groundwater system. The hydraulic groundwater model was calibrated and validated against observed groundwater levels before and after a pumping test. The hydraulic groundwater model was then used to implement a fictitious geothermal energy storage with MT3DMS. MT3DMS is a modular function used with MODFLOW, which can be modified to simulate heat transport. The result shows that the geothermal energy storage can store seasonal heating and cooling of about 4 GWh, which covers 85 % of the hospital’s heating demand with an assumed SP-factor of 4, and the entire cooling demand. To cover 50 % of the peak heating power it was calculated that a flow of 63 l/s was needed, and according to the model this is possible. The geothermal energy storage does not need to be completely in energy balance, since the aquifer is recharged with its natural groundwater. The location of the wells influences which flows that are needed to create energy balance. A too close placement of the wells leads to a thermal breakthrough. The hydraulic conductivity of the esker material affects the amount of energy that can be stored. A higher hydraulic conductivity provides greater energy losses and a lower hydraulic conductivity favors the energy storage but gives a greater influence area. A number of assumptions have been made in the model construction of the hydrogeological model and further investigation of the geological and hydrogeological conditions are desirable to improve the model.

Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-10Bitstream added on 2014-06-13T20:33:56Z : No. of bitstreams: 1 teramoto_eh_me_rcla.pdf: 2690171 bytes, checksum: e9bf862dfe4d665dcbf73deb1105b9b7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Em área contaminada por hidrocarbonetos, situada no município de Paulínia, a migração dos contaminantes e a eficiência do sistema de bombeamento são governadas pela heterogeneidade litológica do aqüífero local, constituído por rochas do Subgrupo Itararé, rochas intrusivas básicas da Formação Serra Geral e por sedimentos cenozóicos correlatos à Formação Rio Claro. Desta forma, o entendimento da heterogeneidade que caracteriza este aqüífero e suas propriedades hidráulicas é essencial para a otimização e o aprimoramento do processo de remediação. Visando delinear o entendimento e a caracterização hidrogeológica local, foi elaborado modelo hidrogeológico conceitual, por meio da integração de dados provenientes de técnicas tradicionais de investigação, tais como métodos geofísicos, monitoramento dos níveis piezométricos de poços de monitoramento, descrições geológicas e análises granulométricas, para entendimento da dinâmica de fluxo local, distribuição litológica do substrato aqüífero e seus valores de condutividade hidráulica. Foram ainda realizadas simulações numéricas de fluxo em regime permanente, utilizando o software Visual Modflow, que emprega o método de diferenças finitas para testar o modelo conceitual concebido. A simulação numérica apresentou excelentes correlações entre os valores de cargas hidráulicas medidas e simuladas e os resultados obtidos permitiram verificar a consistência do modelo conceitual. / In an hydrocarbon contaminated area locate in Paulínia city, lithological heterogeneity of local aquifer controls the migration of contaminant and the efficiency of pump system. The aquifer is composed by sedimentary rocks of Itararé Sub-group, basic intrusive of Serra Geral Formation and cenozoic sediments correlated to Rio Claro Formation. Therefore, understanding heterogeinity that characterize the aquifer and its hydraulic properties is vital to optimization and improvement of remediation process. For hydrogeological characterization of the local aquifer, a conceptual hydrogeological model was elaborated by integrating traditional investigations tools, such as geophysical methods, piezometric level monitoring, and geological descriptions in drillings and granulometric analysis to understanding of local dynamic flow, lithological distributions and hydraulic conductivity. Numerical simulation under steady-state condition using Visual Modflow, which utilizes the finite differences method were performed to test the conceived conceptual model. The measured and calculated hydraulic heads are in excellent agreement, showing the consistency of the conceptual model.

At Bromma Stockholm Airport, fire drills have previously been performed at a location outside the current airport confinements. Fire drills were performed with extinguisher foams containing toxic perfluorooctanesulfonic acid (PFOS), which have polluted the site. Harmful effects of PFOS include but are not limited to damages to the endocrine system. The contaminant is relatively soluble and can be transported by water. The aim of this thesis was to model groundwater flows and PFOS transport in the area. In order to build the model, data was gathered from databases, literature studies and field investigations. The field investigations included geophysical measurements. The model was built in the software Visual MODFLOW Classic. It was used to increase knowledge of hydrogeological conditions in the area, predict the fate of PFOS leaching from the site and suggest preventative measures for preventing the spread. The model results showed that the contaminant is transported towards the current airport area by means of groundwater at a slow rate and with low concentrations. Additionally, high concentrations of PFOS will remain in soil and groundwater at the study area for several hundreds of years, according to model results. Preventative measures should therefore be focused on minimizing risks to frequent visitors to the site, which is currently used as a golf course.

Groundwater is one of the main sources of drinking water in Sweden. Groundwater fluctuations and the detection of flow direction is of significant environmental importance especially when there is a risk for transport of contaminations. The Swedish Nuclear Fuel and Waste Management Company (SKB) has done detailed geotechnical investigations at two potential sites for a final nuclear waste deposition. This report presents the results from groundwater modeling in quaternary deposits in one of these sites. A steady state three dimensional groundwater model was developed for a 71 km2 large area in the Laxemar-Simpevarp, 320 km south of Stockholm close to the nuclear power plant Simpevarp. For this purpose, the Groundwater Modelling System (GMS) was used. The model uses finite difference method to solve the partial differential equation for the water movement with constant density through porous medium. The main objectives were to predict the groundwater heads and the flow directions, and to study the water balance. A conceptual model approach was used by creating five heterogynous soil and rock layers. GIS (Geographic Information System) was used to create top and bottom elevation of the layers by interpolating the GIS data. The model was calibrated using observation data in groundwater monitoring wells and the optimum values for recharge and hydraulic values were found. The numerical simulation was done for two different grid sizes (511×316 m2 and 255×158 m2) referred to coarse and fine grid model respectively. Results from the multilayer model showed flow towards the sea and in the quaternary deposits but not in high elevated rocks. The water balance in the multilayer model was satisfied in both grid sizes. The 3D groundwater model GMS was successfully applied to the large Laxemar-Simpevarp region. The choice of grid size was studied and better agreements between observed and simulated groundwater heads were found in the finer grid model. Large simulation errors in some of the observation wells can indicate GMS model’s weakness in modelling thin soil layers and large variance in topography.

Numeric groundwater modeling techniques can assist water resources regulators pursuing prudent and foresightful aquifer management decisions. Unfortunately, the amount of time and professional expertise required to wield modern groundwater models often exceeds the resources of regulating agencies – even for simple modeling tasks that are repetitive in nature. In an effort to increase the accessibility of groundwater modeling resources, a server-based automated well permitting decision support system was designed. The prototype system allows a user to 1) input properties for any number of candidate wells, 2) execute an associated MOFLOW model, and 3) view relevant results of the simulation on a map such as drawdown contours and regions of decreased spring flow. The system extends the existing concept of automated well permitting geoprocessing, which involves customizable tools built with ArcGIS and Arc Hydro Groundwater geoprocessing components, by moving the geoprocessing tool to a server and creating an interactive web interface built with the Google Earth plug-in. Several strategies to initiate the server-based geoprocessing tool were considered, with and without ArcGIS Server software. A realistic case study was included to demonstrate the system in action. Such server-based automated decision support systems have promising potential to increase the accessibility of groundwater models, facilitating professional management of crucial water resources.

The goal of this study was to determine the impact of land use activities on the subsurface flow regime in the Upper Roanoke River Watershed in Virginia to determine the impacts of land use change on the subsurface flow system, and to provide a tool for future management decisions. Land use activities can impact the groundwater system in two ways. The volume of water recharging the groundwater system can be reduced due to an increase in low permeable areas. It is assumed in this investigation that the input recharge values reflect the increase of low permeability zones that may occur due to land use activities. Increased water withdrawal associated with an increase in population can be another impact of land use change. This possible increase in water withdrawal is explicitly simulated in this investigation. MODFLOW, the USGS, three-dimensional, finite-difference, groundwater flow model was used to develop a regional conceptualization of the flow system. The fractured bedrock aquifer system consists of three sloping geohydrologic units: the Ordovician to Mississippian clastics, the Cambrian and Ordovician carbonates, and the Precambrian and Cambrian metamorphics and clastics. The 575 mi² study area was divided into cells with dimensions of 0.25 miles by 0.25 miles and containing four layers. The upper model layer was used to simulate the saturated unconsolidated deposits that lie on top of the fractured bedrock and serve primarily as a recharge reservoir. The second layer simulated shallow flow driven by recharge and the withdrawal of water by pumping wells. The bottom two layers were used to simulate deep regional flow within the system and account for possible vertical flow that may be occurring through deep fractures. Several simplifying assumptions were made during the conceptualization of groundwater flow in the study area: (1) Flow through fractures is approximately equivalent to flow through a porous medium; (2) Darcy's Law is applicable from a regional perspective; (3) Hydraulic properties are homogeneous and isotropic for an area that is represented by a model cell; and (4) Groundwater flow divides correspond to surface-water flow divides. Although these assumptions are probably valid for parts of the study area, the validity of each assumption is mostly unknown. Therefore, the model results are considered to be conceptual and should be interpreted carefully. The groundwater flow model was calibrated using UCODE, a USGS code for universal inverse modeling. Parameter estimation was conducted using UCODE for a total of 18 parameters, including hydraulic conductivities, river bottom conductance values, and recharge rates. The model was calibrated to observed hydraulic head information from 1969-1970. Due to the limited data availability, however, the calibrated values are at best, approximate. Nonetheless, several inferences can be made regarding flow in the province. The calibrated recharge values indicate that approximately 28% of the total precipitation recharges the aquifer system. This is consistent with previous estimates performed in the study area (Rutledge, Mesko, 1996). The Cambrian and Ordovician carbonates were found generally to have the highest hydraulic conductivity in each layer which reflects the notion that due to dissolution, this geohydrologic unit contains more fractures than the other two units. The calibrated values of hydraulic conductivity for the Cambrian and Ordovician carbonates ranged from 0.89m/d in layer 2 to 0.0011m/d in layer 4. The calibrated values of hydraulic conductivity for the Precambrian and Cambrian metamorphics and clastics ranged from 0.013m/d in layer 2 to 0.708E-3m/d in layer 4, and for the Ordovician to Mississippian clastics followed a similar trend in layers 2 and 3, with values of 0.390m/d in layer 2 and 0.242E-4m/d in layer 3. The streambed conductance values reflected both the variation in streambed thickness, which ranges from nonexistent in some areas to several feet thick in others, and streambed material, which ranges from sandy material with relatively high conductivity values to silty material with lower hydraulic conductivity values. The streambed conductance values range from 4.79 m²/d in the upland reaches to 234.13 m²/d in reaches closer to the outlet. Present pumping conditions were simulated with the groundwater flow model to establish a "baseline simulation" to which all future scenarios could be compared. Three future scenarios were developed based on the projected increase in population for Roanoke County through the year 2010. Each scenario represented a distinct settlement pattern within the watershed. Development scenario 1 simulated the impacts of the increased population if settled in the same areas as present development. Development scenario 2 simulated the impacts of the increased population if half settled in areas of present development and the other half in the western half of the watershed. Development scenario 3 simulated the impacts of the increased population if half of the population increase settled in areas of present development and the other half settled in the Tinker Creek sub-watershed. Development scenario 2 resulted in a drastic change in hydraulic head values, and the volume of water discharged from the streams was, on average, reduced by 56%, whereas, for both scenarios 1 and 2, these reductions were less than 1%. Results indicate that flow in the system is predominantly horizontal. There is no deep vertical flow from possible deep fractures. There may be shallow vertical flow occurring that is driven by recharge, however due to the resolution of the model, this flow is not simulated. In general, the simulation of horizontal flow follows the overall trend of the hydraulic gradient from west to east, which also follows the overall topographic trend. Therefore, upland regions in the province are recharging down-gradient areas. However, simulations indicate that the hydraulic head values in the eastern part of the study area are relatively insensitive to this horizontal recharge contribution from the west. The most sensitive areas in the basin to increased water withdrawal are the upland areas in the west side of the study area that are receiving no horizontal flow contribution from other places in the watershed. These areas are only being recharged by precipitation, and are the first to react to regional flow changes. Since the resolution of the model is such that local variations in the flow system are not simulated and the model represents regional trends, inferences can only be made about regional impacts. Therefore, if increased withdrawals are so great as to impact the regional system, the west- side of the study area will be affected before all other areas in the watershed. The study results include estimates of hydraulic properties, direction of regional flow, possible impacts from land use change, and a discussion of the results with respect to gaining a more complete understanding of the subsurface flow system. Perhaps this work will be the first step in learning more about the subsurface flow system of the Upper Roanoke River Watershed, and provide a useful tool to manage and properly plan future land use changes to minimize the impacts on the groundwater resources of the basin. / Master of Science