Résumé : Les eaux souterraines ont un impact majeur sur la vie terrestre, les besoins domestiques et le climat. Elles sont aussi un maillon essentiel du cycle hydrologique. Au Canada par exemple, plus de 30 % de la population est tributaire des eaux souterraines pour leur alimentation en eau potable. Ces ressources subissent de nombreuses pressions sous l’influence de certains facteurs comme la salinisation, la contamination et l’épuisement. La variabilité du climat et la demande croissante sur ces ressources imposent l'amélioration de nos connaissances sur les eaux souterraines. L’objectif principal du projet de recherche est d’exploiter les données d’anomalies (TWS) de la mission Gravity Recovery And Climate Experiment (GRACE) pour localiser, quantifier et analyser les variations des eaux souterraines à travers les bassins versants du Bas-Mackenzie, du Saint-Laurent, du Nord-Québec et du Labrador. Il s’agit aussi d’analyser l’influence des cycles d’accumulation et de fonte de neige sur les variations du niveau des eaux souterraines. Pour estimer les variations des eaux souterraines, la connaissance des autres paramètres du bilan hydrologique est nécessaire. Ces paramètres sont estimés à l’aide des sorties du modèles de surface CLM du Système Global d’Assimilation des Données de la Terre (GLDAS). Les données GRACE qui ont été utilisées sont celles acquises durant la période allant de mars 2002 à août 2012. Les résultats ont été évalués à partir d’enregistrements de niveaux piézométriques provenant de 1841 puits localisés dans les aquifères libres du bassin des réseaux de suivi des eaux souterraines au Canada. Les valeurs de rendements spécifiques des différents types d’aquifères de chaque puits et celles des variations mensuelles du niveau d’eau dans ces puits ont été utilisées pour estimer les variations des anomalies des eaux souterraines in-situ. L’étude de corrélation entre les variations des anomalies des eaux souterraines estimées à partir de la combinaison GRACE-GLDAS et celles issues de données in-situ révèle des concordances significatives avec des valeurs de 𝑅=0,46 et 𝑅 = 0,50 entre ΔGW et ΔGWPiézo, respectivement pour le bassin du Bas-Mackenzie et celui du Saint-Laurent. Quant à la combinaison de tous les bassins, elle s’est caractérisée par une corrélation un peu plus faible (𝑅=0,44). Les valeurs des coefficients de corrélation calculée avec des données indépendantes de SWE venant des produits GlobSnow ; R = -0,68 sur le bassin du Bas-Mackenzie, R = -0,76 sur le bassin versant du Nord-du-Québec et du Labrador, R = -0,51 sur le bassin versant du Saint-Laurent et R = -0,52 pour les trois bassins réunis, montrent que ΔGW est très sensible à la quantité d’eau dans la neige, avec des spécificités pour chaque bassin versant étudié. / Abstract : Groundwater is an important component of the hydrological cycle. In Canada, more than 30% of the population relies on the main source of water for domestic use. These resources are under pressure factors such as salinization, contamination and exhaustion. Our knowledge on groundwater needs improvement because of climate variability and an increasing demand for these resources. The main objective of this project is to use the Gravity Recovery And Climate Experiment (GRACE) mission data (TWS) anomalies to locate, quantify and analyze the groundwater changes in Mackenzie St. Lawrence, North-Quebec and Labrador basins. Also this work aims to analyze the influence of accumulation cycles and snowmelt on groundwater level changes. For this groundwater changes estimation, it is necessary to estimate other water balance parameters. These parameters are estimated by using the outputs of the land surface model CLM of the Global Land Data Assimilation System (GLDAS) Data Products. The TWS data used are from March 2002 to august 2012. The results were evaluated by using the groundwater levels records from 1841 wells located in the free aquifers of different Canadian groundwater monitoring networks. The Specific yields values of the different types of aquifers from each well and the monthly changes in the water level in these wells were used to estimate changes in the in-situ groundwater anomalies. The correlation study between changes in groundwater anomalies estimated from the combination GRACE-GLDAS and those from in-situ data reveals significant matches with values of R = 0,46 and R = 0,50 between ΔGW and ΔGWPiézo respectively for the Lower-Mackenzie and the St. Lawrence basins. The combination of all the basins is characterized by a slightly weaker correlation (R = 0, 44).The correlation coefficients calculated with an independent data coming from SWE GlobSnow products are R = -0, 68 for Lower-Mackenzie River Basin, R = -0, 76 for Nord-du-Québec and Labrador basin, R = -0, 51 for St. Lawrence basin and R = -0, 52 for the three basins taken together. These correlations show that ΔGW is very sensitive to the snowmelt water amount, but with specificities for each studied basin.

The goal of this study is to evaluate Swedish photovoltaic systems regarding energy production from two different years and compare the gathered data with results from a model simulating optimal conditions. This is done to investigate how the energy production differs between each year, why there are differences, and also to evaluate the simulation tools compared to the real production data. A good way to measure performance is to calculate the specific yield, that is the energy produced per unit of installed power (kWh/kWp). In order to complete this study, a literature study was made to investigate reasons for potential variations in PV system yield. Besides that, the production data from 2373 PV systems in Sweden were collected from different databases, and the data were sorted and compiled in order to calculate specific yield (kWh/kWp). The total number of PV systems after sorting was 828 for the 2017-2018 data and 1380 systems for the 2018 data. Data from real PV system production was compared with calculations performed in two simulation tools, PVGIS and PVsyst. Differences in calculation methods were investigated for performance evaluations between the two programs, and also for comparison with the real plant data. The results showed that the average specific yield for Sweden as a whole, to be 798 kWh/kWp for 2017. For 2018 with the results where 890 kWh/kWp when looking at the exact same plants as for 2017. This is an increase of 11,5%. For the simulation tools the results where 974 kWh/kWp for PVGIS, and 978 for PVsyst for an optimized system. Larger variations in specific yield occurs between every of the 21 counties in Sweden. The solar irradiations show significant correlations to the variations of the 2017 and 2018 specific yield data. Differences between the production data from the two years and the simulation tools wereinvestigated further. Reasons for this was discussed to be because of orientations of the panels and shading of the panels. Real PV systemsdiffer in orientation and the amount of shadowing from the simulated calculations.

Este trabalho foi desenvolvido com o objetivo de determinar a recarga profunda na bacia do Ribeirão da Onça utilizando modelo de balanço hídrico em zona saturada do solo. A bacia está localizada na região de afloramento do Sistema Aqüífero Guarani (SAG) no Estado de São Paulo sendo recoberta, em sua maior parte, por solo do tipo sedimento cenozóico e apresentando afloramento de basalto em pequena região próxima a seu exutório. O modelo do balanço hídrico envolveu a determinação dos valores de recarga direta, variação do armazenamento do aqüífero freático e escoamento básico. Para a obtenção destes valores foi monitorada a precipitação diária na bacia, a vazão na seção de controle do ribeirão e nível d\'água nos poços de monitoramento instalados na bacia, estes dois últimos com freqüência quinzenal. A recarga direta foi determinada pelo método da variação da superfície livre - Water Table Fluctuation (WTF). O escoamento básico foi calculado por meio de separação de hidrograma, o qual foi gerado por modelo chuva-vazão apoiado em medidas quinzenais da vazão na seção de controle. Amostras indeformadas de solo foram coletadas nas profundidades correspondentes à zona de variação do nível do aqüífero freático para a determinação do rendimento específico do solo. O rendimento específico médio para o solo da bacia, determinado por método de tensão de água no solo utilizando funil de placa porosa (Funil de Haines), foi de 12,2%. Este valor compatível com dados da literatura para o tipo de solo. Foram executados balanços hidrológicos em zona saturada no período de fevereiro de 2004 a janeiro de 2007, separados um dos 3 anos hidrológicos. A recarga direta variou de 14% a 38% e a recarga profunda variou de 0,4 % a 2,4% das respectivas precipitações no período. Os baixos valores de recarga profunda encontrados no trabalho revelam a necessidade da continuidade de estudos das estimativas de disponibilidade hídrica sustentável do Sistema Aqüífero Guarani. / Main objective of this work was the determination of the deep recharge in the Ribeirão da Onça basin through water balance in the soil saturated zone. This basin is located in the outcrop zone of the Guarani Aquifer System (GAS) in the São Paulo State - Brazil and is covered by cenozoic sedimentary soil. The water balance model involved the determination of the direct recharge, groundwater storage variation and base flow. To obtain these values, the daily precipitation in the basin, the stream flow in the outflow section of the creek and the aquifer level fluctuation in wells installed in the basin was monitored. The direct recharge was determined by the water table fluctuation method (WTF). The base flow was calculated by hydrograph separation method generated by rain-flow model supported by biweekly stream flow measurements. Undisturbed soil samples were collected with the objective of determining the effective porosity (specific yield). The effective porosity is 12.2%, compatible with values found in the literature. Water balances were executed for each one of the 3 hydrological years (February/2004 to January/2007). The direct recharge varied between 14% while 38% and the deep recharge varied between 0.4% and 2.4% of the respective precipitations in the period. The low values of deep recharge reveal the need for the continuity of the water resources studies in the Guarani Aquifer System.

This dissertation focuses on a variety of vadose zone processes that impact water table fluctuations. The development of vadose zone process conceptualization has been limited due to both the lack of recognition of the importance of the vadose zone and the absence of suitable field data. Recent studies have, however, shown that vadose zone soil moisture dynamics, especially in shallow water table environments, can have a significant effect on processes such as infiltration, recharge to the water table, and evapotranspiration. This dissertation, hence, attempts to elucidate approaches for modeling vadose zone soil moisture dynamics. The ultimate objective is to predict different vertical and horizontal hydrological fluxes. The first part of the dissertation demonstrates a new methodology using soil moisture and water table data collected along a flow transect. The methodology was found to be successful in the estimation of hydrological fluxes such as evapotranspiration, infiltration, runoff, etc. The observed dataset was also used to verify an exponential model developed to quantify the ground water component of total evapotranspiration. This analysis was followed by a study which analyzed the impact of soil moisture variability in the vadose zone on water table fluctuations. It was found that antecedent soil moisture conditions in the vadose zone greatly affected the specific yield values, causing a broad range of water table fluctuations for similar boundary fluxes. Hence, use of a constant specific yield value can produce inaccurate results. Having gained insight into the process of evapotranspiration and specific yield, a threshold based model to determine evapotranspiration and subsequent water table fluctuation was conceptualized and validated. A discussion of plant root water uptake and its impact on vadose zone soil moisture dynamics is presented in the latter half of this dissertation. A methodology utilizing soil moisture and water table data to determine the root water uptake from different sections of roots is also described. It was found that, unlike traditional empirical root water uptake models, the uptake was not only proportional to the root fraction, but was also dependent on the ambient soil moisture conditions. A modeling framework based on root hydraulic characteristics is provided as well. Lastly, a preliminary analysis of observed data indicated that, under certain field conditions, air entrapment and air pressurization can significantly affect the observed water table values. A modeling technique must be developed to correct such observations.

An analytical model is presented for the analysis of pulse interference tests conducted in a fractured porous medium with connection to a free surface boundary at the water table. The solution is applicable to open borehole pulse interference tests due to the accommodation of multiple horizontal fractures intersecting each wellbore and a connection from the uppermost horizontal fracture to a free surface boundary. The solution is derived using the Laplace transform method and evaluation of the solution is performed by numerical inversion using the Talbot algorithm. Based on an informal sensitivity analysis, unique values for transmissivity, storativity, specific storage, vertical hydraulic conductivity and specific yield are predicted over a range of realistic values for these parameters. The analytical model is used to analyze slug tests and pulse interference tests conducted in a fractured gneiss formation. The results of these tests are compared to long-term pumping tests to identify the effect of measurement scale on transmissivity, storativity, vertical hydraulic conductivity and specific yield obtained in a fractured rock setting. Scale artefacts relating to measurement or analysis methods are minimized through the use of consistent well configurations in each of the applied hydraulic testing methods. The geometric mean estimates of transmissivity and storativity are shown to vary by less than an order of magnitude from local-scale tests to long-term pumping tests. The geometric mean specific yield result from a series of pulse interference tests that samples both highly fractured and poorly fractured portions of the rock formation approximates the long-term pumping test estimate of specific yield. The geometric mean result for vertical hydraulic conductivity decreases by approximately 1.5 orders of magnitude from the slug test to pumping test scale; however, pulse interference tests conducted on highly fractured portions of the formation produce vertical hydraulic conductivity estimates that are within a half order of magnitude of the long-term pumping test results. This suggests that the performance of pulse interference tests on a highly fractured portion of a rock formation may be a less time-intensive alternative to large-scale pumping tests in the determination of vertical hydraulic conductivity. / Thesis (Master, Civil Engineering) -- Queen's University, 2011-06-24 19:29:52.743

Este trabalho foi desenvolvido com o objetivo de determinar a recarga profunda na bacia do Ribeirão da Onça utilizando modelo de balanço hídrico em zona saturada do solo. A bacia está localizada na região de afloramento do Sistema Aqüífero Guarani (SAG) no Estado de São Paulo sendo recoberta, em sua maior parte, por solo do tipo sedimento cenozóico e apresentando afloramento de basalto em pequena região próxima a seu exutório. O modelo do balanço hídrico envolveu a determinação dos valores de recarga direta, variação do armazenamento do aqüífero freático e escoamento básico. Para a obtenção destes valores foi monitorada a precipitação diária na bacia, a vazão na seção de controle do ribeirão e nível d\'água nos poços de monitoramento instalados na bacia, estes dois últimos com freqüência quinzenal. A recarga direta foi determinada pelo método da variação da superfície livre - Water Table Fluctuation (WTF). O escoamento básico foi calculado por meio de separação de hidrograma, o qual foi gerado por modelo chuva-vazão apoiado em medidas quinzenais da vazão na seção de controle. Amostras indeformadas de solo foram coletadas nas profundidades correspondentes à zona de variação do nível do aqüífero freático para a determinação do rendimento específico do solo. O rendimento específico médio para o solo da bacia, determinado por método de tensão de água no solo utilizando funil de placa porosa (Funil de Haines), foi de 12,2%. Este valor compatível com dados da literatura para o tipo de solo. Foram executados balanços hidrológicos em zona saturada no período de fevereiro de 2004 a janeiro de 2007, separados um dos 3 anos hidrológicos. A recarga direta variou de 14% a 38% e a recarga profunda variou de 0,4 % a 2,4% das respectivas precipitações no período. Os baixos valores de recarga profunda encontrados no trabalho revelam a necessidade da continuidade de estudos das estimativas de disponibilidade hídrica sustentável do Sistema Aqüífero Guarani. / Main objective of this work was the determination of the deep recharge in the Ribeirão da Onça basin through water balance in the soil saturated zone. This basin is located in the outcrop zone of the Guarani Aquifer System (GAS) in the São Paulo State - Brazil and is covered by cenozoic sedimentary soil. The water balance model involved the determination of the direct recharge, groundwater storage variation and base flow. To obtain these values, the daily precipitation in the basin, the stream flow in the outflow section of the creek and the aquifer level fluctuation in wells installed in the basin was monitored. The direct recharge was determined by the water table fluctuation method (WTF). The base flow was calculated by hydrograph separation method generated by rain-flow model supported by biweekly stream flow measurements. Undisturbed soil samples were collected with the objective of determining the effective porosity (specific yield). The effective porosity is 12.2%, compatible with values found in the literature. Water balances were executed for each one of the 3 hydrological years (February/2004 to January/2007). The direct recharge varied between 14% while 38% and the deep recharge varied between 0.4% and 2.4% of the respective precipitations in the period. The low values of deep recharge reveal the need for the continuity of the water resources studies in the Guarani Aquifer System.

Em zonas ripárias o nível freático encontra-se próximo à superfície do solo e tem contato com as raízes da vegetação. Como resultado, as taxas de evapotranspiração (ET) são elevadas, gerando flutuações diárias do nível de água subterrânea. Apesar da riqueza hídrica que a América Latina possui, estudos sobre a evapotranspiração nas suas zonas ripárias são raros. Os prováveis motivos da pouca investigação na área podem ser atribuídos ao difícil acesso econômico para adquirir equipamentos necessários para a sua medição. Além disso, a aplicação de técnicas como sensoriamento remoto, eddy covariance ou a razão de Bowen é limitada, devido à bordadura das zonas ripárias, que geralmente é estreita. O objetivo deste trabalho foi determinar a ET em zona ripária e áreas vizinhas através de métodos baseados na flutuação diária do nível de água subterrânea. No desenvolvimento deste estudo foram instalados poços de monitoramento na bacia hidrográfica do Ribeirão da Onça. A profundidade do nível freático foi registrada em dataloggers em intervalos de 15 minutos, no período de 09/2015 a 10/2016. O rendimento específico transiente (S*y) foi estimado através da modernização do funil de Haines acoplado a uma balança de precisão.Em função do regime de flutuação diária do nível freático, foi adotado o S*y correspondente a 6 horas de drenagem. Os resultados mostram que na zona ripária a evapotranspiração oscila entre 2,74 e 14,90 mm/d. Para o Cerrado stricto sensu e o eucalipto, a variação da ET é de 1,23 a 2,02 mm/d e 1,96 a 5,45 mm/d, respectivamente, sendo coerentes com resultados prévios obtidos no Brasil. A aplicação de métodos da flutuação diária mostra ser economicamente viável e ter potencial para estimar a evapotranspiração em áreas estreitas. / In riparian zones the groundwater is close to the soil surface and the roots of its vegetation have contact with it. As a result, evapotranspiration (ET) rates are high, generating diurnal groundwater level fluctuations. Despite Latin America\'s water resources wealth, reports of evapotranspiration in its riparian zones are scarce. The probable reasons of little investigation in the area can be attributed to the economical difficulties to access the equipments necessary for this kind of measurement. Furthermore, the application of techniques as remote sensing, eddy covariance or Bowen ratio is limited, due to the usual narrow fetch that are found in the riparian zones. The aim of this study was to determine the ET in the riparian zone and its surroudings areas, using methods based on the diurnal groundwater level fluctuations. To develop this study, monitoring wells were installed in the Ribeirão da Onça basin. The water table depth was recorded in dataloggers using a 15-minute interval, from 09/2015 to 10/2016. The transient specific yield was estimated by improving the Haines funnel coupled to a precision balance. In function of the daily fluctuation regime of the groundwater table, it was adopted the S*y corresponding to 6 hours of drainage. The results show that, in the riparian zone, evapotranspiration ranges from 2,74 to 14,90 mm/d. For Cerrado stricto sensu and eucalyptus, the ET variations are 1,23 to 2,02 mm/d and 1,96 to 5,45 mm/d, respectively, being consistent with previous studies performed in Brazil. The application of diurnal groundwater level fluctuations methods shows to have the potential to estimate evapotranspiration in narrow areas, with low economic investment.

Em zonas ripárias o nível freático encontra-se próximo à superfície do solo e tem contato com as raízes da vegetação. Como resultado, as taxas de evapotranspiração (ET) são elevadas, gerando flutuações diárias do nível de água subterrânea. Apesar da riqueza hídrica que a América Latina possui, estudos sobre a evapotranspiração nas suas zonas ripárias são raros. Os prováveis motivos da pouca investigação na área podem ser atribuídos ao difícil acesso econômico para adquirir equipamentos necessários para a sua medição. Além disso, a aplicação de técnicas como sensoriamento remoto, eddy covariance ou a razão de Bowen é limitada, devido à bordadura das zonas ripárias, que geralmente é estreita. O objetivo deste trabalho foi determinar a ET em zona ripária e áreas vizinhas através de métodos baseados na flutuação diária do nível de água subterrânea. No desenvolvimento deste estudo foram instalados poços de monitoramento na bacia hidrográfica do Ribeirão da Onça. A profundidade do nível freático foi registrada em dataloggers em intervalos de 15 minutos, no período de 09/2015 a 10/2016. O rendimento específico transiente (S*y) foi estimado através da modernização do funil de Haines acoplado a uma balança de precisão.Em função do regime de flutuação diária do nível freático, foi adotado o S*y correspondente a 6 horas de drenagem. Os resultados mostram que na zona ripária a evapotranspiração oscila entre 2,74 e 14,90 mm/d. Para o Cerrado stricto sensu e o eucalipto, a variação da ET é de 1,23 a 2,02 mm/d e 1,96 a 5,45 mm/d, respectivamente, sendo coerentes com resultados prévios obtidos no Brasil. A aplicação de métodos da flutuação diária mostra ser economicamente viável e ter potencial para estimar a evapotranspiração em áreas estreitas. / In riparian zones the groundwater is close to the soil surface and the roots of its vegetation have contact with it. As a result, evapotranspiration (ET) rates are high, generating diurnal groundwater level fluctuations. Despite Latin America\'s water resources wealth, reports of evapotranspiration in its riparian zones are scarce. The probable reasons of little investigation in the area can be attributed to the economical difficulties to access the equipments necessary for this kind of measurement. Furthermore, the application of techniques as remote sensing, eddy covariance or Bowen ratio is limited, due to the usual narrow fetch that are found in the riparian zones. The aim of this study was to determine the ET in the riparian zone and its surroudings areas, using methods based on the diurnal groundwater level fluctuations. To develop this study, monitoring wells were installed in the Ribeirão da Onça basin. The water table depth was recorded in dataloggers using a 15-minute interval, from 09/2015 to 10/2016. The transient specific yield was estimated by improving the Haines funnel coupled to a precision balance. In function of the daily fluctuation regime of the groundwater table, it was adopted the S*y corresponding to 6 hours of drainage. The results show that, in the riparian zone, evapotranspiration ranges from 2,74 to 14,90 mm/d. For Cerrado stricto sensu and eucalyptus, the ET variations are 1,23 to 2,02 mm/d and 1,96 to 5,45 mm/d, respectively, being consistent with previous studies performed in Brazil. The application of diurnal groundwater level fluctuations methods shows to have the potential to estimate evapotranspiration in narrow areas, with low economic investment.

Southeast Australia have between 1997-2009 experienced a severe drought, referred to as the Millennium Drought. During these years the region experienced a 11.4% decline in mean annual rainfall, an unprecedented decrease in runoff and a decline in soil moisture and groundwater storage. The drought officially ended in 2010 when one of the strongest La Nina-events on record occurred. However, it is still unknown how the behaviour of the catchments changed during the drought and if this change persists in the years following the drought. Changes in catchment behaviour and fluxes are commonly determined using a catchment water balance, where the change in groundwater storage is assumed to be neglectable when studying longer periods of time. However, studies have showed that this assumption might be inaccurate for catchments that experience a climatic disturbance such as a severe drought. This study investigates if including the change in groundwater storage by using spatial groundwater head data can improve the catchment water balance. This was done by assuming that specific yields are unknown and to be determined in a calibration. An unknown scalar applied to the evapotranspiration was used to try to account for the uncertainties in the known fluxes and was also to be determined in the calibration. Two different calibration schemes were considered: one assuming no delay in groundwater head response to climate and one accounting for the delay. The fluxes were determined for the period before, during and after the drought. The results were analysed to determine if the catchments showed a change in behaviour during and after the drought. The results showed that when not accounting for the delayed response of the groundwater head, at least one of the specific yields in the catchments became infinitely small. Including the delayed groundwater head response did improve one of the catchments significantly by producing plausible specific yields for all geological units. A conclusion of this is that including the change in groundwater storage could improve the water balance. However, for it to do so a thorough analysis of the groundwater and subsurface needs to be conducted. Further, the water balance error was the third biggest flux after rainfall and actual evapotranspiration suggesting that the evapotranspiration scalar reduced the actual evapotranspiration too much. All fluxes did decrease during the drought, by how much differed between the catchments and the water balance components. Two of the catchments showed a change in behaviour during the drought that persisted in the years following the drought. The most likely fluxes to have caused this were the change in runoff and groundwater storage. The other two catchments showed a smaller change in behaviour during the drought and an indication that it was on its way back to the same state as before the drought. The likely fluxes to have caused the small change in behaviour was runoff and actual evapotranspiration. / Under åren 1997–2009 minskade den genomsnittliga årliga nederbörden över sydöstra Australien med 11.4% och den genomsnittliga årliga avrinningen var lägre än någonsin tidigare samtidigt som grundvattennivåerna sjönk. Denna torka brukar kallas the Millennium Drought och är den svåraste torkan i Australien i modern tid. Torkan tog officiellt slut 2010 då ett av de mest kraftfulla La Niña-fenomenen inträffade vilket bidrog till att april 2010 till mars 2012 var de blötaste två åren i australiensk historia. Trots att flera studier har gjorts kring torkan så är det ännu inte klarlagts hur avrinningsområdena i området påverkades och om de fortfarande är påverkade när torkan officiellt är över. Flödena inom ett avrinningsområde bestäms vanligtvis genom en vattenbalans. Då vattenbalansen över ett avrinningsområde studeras under en längre tid antas ofta att förändringarna i grundvattenmagasinen går att bortse från då grundvattennivån ofta återgår till samma stadie efter ett antal år. Nyare studier har dock visat att detta inte alltid är fallet vid exempelvis en svår torka och att det vid dessa fall inte är korrekt att anta att förändringen i grundvattenmagasinen är försumbar. I denna studie har en vattenbalans gjorts för fyra avrinningsområden i delstaten Victoria i Australien. Syftet har varit att avgöra om vattenbalansen kan förbättras om förändringen i grundvattenmagasinen inkluderas. Detta har gjorts genom att använda nyligen framtagen data för grundvattennivån i delstaten och antagit att den dränerbara porositeten är en okänd variabel. För att justera för osäkerheterna kring the kända flödena har en okänd faktor för evapotranspirationen inkluderats. De okända variablerna bestämdes i en kalibrering. Kalibreringen genomfördes för två olika kalibreringsscheman och för tre olika tidsperioder. Det ena kalibreringsschemat antog att grundvattnet direkt reagerade på effektiv nederbörd minus avrinning, medan den andra kalibreringsschemat tog hänsyn till en försenad reaktion. Kalibreringen gjordes för tidsperioderna innan, under och efter torkan. Resultaten visade att när ingen hänsyn togs till en eventuellt försenad reaktion av grundvatten så går värdet för dränerbar porositet i minst en geologisk enhet mot noll medan det andra värdet är rimligt. När hänsyn togs till en försenad reaktion av grundvattnet, fick fler avrinningsområde rimliga värden för dränerbar porositet för hela området. Slutsatsen som kan dras kring detta är att vattenbalansen kan förbättras om förändringen i grundvattenmagasinen inkluderas. Detta kräver dock en djupgående analys av grundvattnet och geologin i avrinningsområdet. Hur mycket flödena förändrades under och efter torkan varierar mellan avrinningsområdena och flödena, gemensamt var dock att alla flöden minskade under torkan. Två av avrinningsområdena påvisade en förändring i beteendet under torkan och de år som följde. Det är mest troligt att förändringarna i avrinning och grundvattenmagasinen har påverkat detta. De övriga två avrinningsområdena påvisade även de en förändring under torkan, om än mindre än för de föregående. Denna förändring ser även ut att vara på tillbakagående och att avrinningsområdet inom en snar framtid skulle kunna ha samma tillstånd som innan torkan. De mest troliga flödena som har påverkat dessa avrinningsområden är förändringar i avrinning och den faktisk evapotranspirationen.

This study is focused on characterization of the hardrock environment in surroundings of Sazava river. It is based on the archival data of groundwater table in boreholes, results of pumping tests from Geofond database and topographic data (DMR , watercourse, etc.). ArcMap 10.1 and Excel were used for data processing. The relations between the groundwater table depth, water table gradient, specific yield, transmissivity and variety of topographic parameters (distance from a watercourse, elevation, relative elevation above the nearest watercourse, the terrain gradient, etc.) were studied. Close linear relationship exists between the gradient of the terrain and groundwater table (rxy 0.96) in the study area. Groundwater table gradient is on average 88 % of terrain gradient. Mean groundwater table gradient is 10 % (6). The average transmissivity in the area is 1.27 x 10-4 m2 /s, specific yield is usually between 0.01 and 0.1 l/s m. This corresponds to the low and very low transmissivity class. Variability of transmisivity values is high. The difference between transmisivity in discharge and recharge zone, assumed by previous authors, was not confirmed in the study area. Specific base flow calculated from mean transmissivity, terrain/ water table gradient and river network density based on Krásný and...