The interaction between drainage from the variably saturated zone above the water table, and the response of an unconfined aquifer to pumping has been the source of debate for many decades. While various field tests (Nwankwor et al., 1992 and Moench et al., 2001) have supported the concept that variably saturated flow processes delay drainage above a falling water table, Neuman (1972, 1974, 1975), has asserted that the impact is minimal, delay in response of the water table is due to elastic storage effects, and instantaneous yield above the water table is a reasonable assumption in unconfined aquifer analysis. This assumption results in exceedingly low estimates of specific yield in comparison to other analysis techniques (Neuman, 1987). A 7-day pumping test by Bevan et al. (2005) in the unconfined aquifer at Canadian Forces Base Borden has highlighted the complexity in drainage from above the water table during pumping, as the tension saturated zone was found to increase in thickness as a function of both proximity to the pumping well, and elapsed pumping time. This extended thickness persisted for the 7-day pumping duration. Analytical analysis of the test by Endres et al. (2007) resulted in significant underestimates of specific yield in comparison to laboratory values for most solutions. Narasimham (2007) suggested that the use of numerical simulators which include variably saturated flow may provide the most accurate representation of the test results. An attempt to replicate test results using a numerical simulation of variably saturated flow by Moench (2008) could not provide a complete physical mechanism for the extension observed by Bevan et al. (2005). This study provides a detailed investigation on the effect of heterogeneity, hysteresis, and entrapped air on drainage during unconfined pumping tests using numerical simulations, field experiments, and laboratory observations. The results of the Bevan et al. (2005) pumping test are used as a standard for comparison. Three variably-saturated groundwater flow numerical codes were evaluated for their ability to replicate the variations in soil moisture content observed during pumping by Bevan et al. (2005). Results of the numerical simulations were also analyzed for their similarity to the peak and subsequent decrease in vertical gradients observed during pumping in the Borden aquifer. While the models generated vertical gradients through the capillary fringe during pumping, these gradients dissipated significantly before 1000 min. of pumping. No gradients in the saturated zone generated by the numerical model would be capable of shifting the pressure head sufficiently to cause an apparent capillary fringe extension following the first few hours of pumping. Significant gradients were persistent throughout the test at locations where saturation was less than 85%. Accounting for the formation of vertical gradients, no simulation was able to replicate the soil moisture distributions observed by Bevan et al. (2005). Based on these results, heterogeneity, hysteresis, and entrapped air were proposed as processes with the potential to significantly affect drainage from above the water table during pumping, as their investigation may provide the physical mechanism for the observed capillary fringe extension. Compaction of the aquifer material was dismissed as a potential mechanism based on the results of a proctor test. The effect of heterogeneity on drainage from the Borden aquifer during pumping was investigated numerically using geostatistical methods. A log-normal saturated hydraulic conductivity distribution was used to represent the Borden aquifer. Brooks and Corey parameters were used to describe the pressure-saturation-relative conductivity relationships. The air-entry pressure parameter was scaled to the saturated conductivity using the scaling relationship for Borden sand proposed by Keuper and Frind (1991). The Brooks and Corey lambda parameter was kept constant. A Monte Carlo analysis was performed on the results. While several realizations of the hydraulic conductivity distribution resulted in the formation of perched water during drainage, the ensemble capillary fringe thickness was unchanged from the thickness generated using a homogeneous conceptual aquifer model. No single realization produced a capillary fringe extension in which the magnitude was a function of elapsed pumping time, or distance from the pumping well. Approximation of the effect of air-entry barriers on drainage did not increase the estimated capillary fringe thickness. The presence and location of finer grained layers appeared to have a much greater impact on the thickness of the capillary fringe than the drawdown induced by pumping. Ensemble results for the hydraulic head drawdown provided improved matches to the field observations in comparison to the homogeneous numerical model during intermediate and late times in the pumping test. A mild degree of heterogeneity appears to have sufficient effect on drainage from above the water table during pumping to impact hydraulic drawdown. The effect would be magnified with the greater degree of heterogeneity that is more typical of natural aquifer systems. A 24-hour pumping test was conducted at CFB Borden to gain a better understanding of the nature of drainage during a pumping test. Due to the wet site conditions prior to the test, the moisture profile during pumping was significantly influenced by hysteresis. The hydraulic head drawdown generated during the test was insufficient to generate any drainage due to the lowering of the top of the saturated zone, and the formation of perched lenses could not occur. Hysteresis in the moisture profile was a controlling factor in this result. Although there was no significant drainage initiated due to the lowering of the top of the saturated zone, an inflection point was still apparent in the time-drawdown curve for the four monitoring wells observed. Vertical gradients measured throughout the saturated zone, including the capillary fringe, remained low throughout the duration of pumping, and no significant increase was apparent in the transition from saturated to tension-saturated conditions. Hysteresis has the potential to increase the delay in drainage as the water table falls during pumping. A laboratory tank apparatus was used to determine the effect of entrapped air, grain size distribution, and horizontal gradient on drainage in a primarily horizontal flow regime. The tank was packed on three separate occasions, once with a coarse well sorted silica sand, and twice with sand from the Borden aquifer. For each packing, the tank was drained twice, using two different horizontal gradient magnitudes. Results show that horizontal gradient magnitude has no impact on soil moisture distributions during drainage. Air-entry pressure was elevated in comparison to gravity drainage derived pressure head – saturation curves. This elevation was not transient, nor dependant on gradient or grain size distribution. The increase in air-entry pressure does not appear to be due to insufficient equilibration time between water level drops or flow redistribution around the TDR Rods. Results of this study support a conceptual model of unconfined aquifer response in which drainage from above the water table is a complex and time dependant process. Individually, heterogeneity and hysteresis have been shown to cause a time delay between the lowering of the water table and the subsequent drainage of the tension saturated zone during intermediate to late pumping times. The magnitude and duration of this delay varies by process and is a function of the degree of heterogeneity, moisture conditions in the aquifer prior to pumping, and the drawdown rate of the water table. While no individual process tested could produce the capillary fringe extension observed by Bevan et al. (2005), the investigation of each has led to an improved conceptual understanding of the response to pumping in unconfined aquifers. Due to the complex interaction of these processes it is unlikely that pumping test results, even those which include moisture content observations, could be used to accurately predict unsaturated flow parameters. Storage parameter (i.e. specific yield) estimates made using analytical solutions may not be appropriate unless delayed drainage from above the water table is properly accounted for.

The interaction between drainage from the variably saturated zone above the water table, and the response of an unconfined aquifer to pumping has been the source of debate for many decades. While various field tests (Nwankwor et al., 1992 and Moench et al., 2001) have supported the concept that variably saturated flow processes delay drainage above a falling water table, Neuman (1972, 1974, 1975), has asserted that the impact is minimal, delay in response of the water table is due to elastic storage effects, and instantaneous yield above the water table is a reasonable assumption in unconfined aquifer analysis. This assumption results in exceedingly low estimates of specific yield in comparison to other analysis techniques (Neuman, 1987). A 7-day pumping test by Bevan et al. (2005) in the unconfined aquifer at Canadian Forces Base Borden has highlighted the complexity in drainage from above the water table during pumping, as the tension saturated zone was found to increase in thickness as a function of both proximity to the pumping well, and elapsed pumping time. This extended thickness persisted for the 7-day pumping duration. Analytical analysis of the test by Endres et al. (2007) resulted in significant underestimates of specific yield in comparison to laboratory values for most solutions. Narasimham (2007) suggested that the use of numerical simulators which include variably saturated flow may provide the most accurate representation of the test results. An attempt to replicate test results using a numerical simulation of variably saturated flow by Moench (2008) could not provide a complete physical mechanism for the extension observed by Bevan et al. (2005). This study provides a detailed investigation on the effect of heterogeneity, hysteresis, and entrapped air on drainage during unconfined pumping tests using numerical simulations, field experiments, and laboratory observations. The results of the Bevan et al. (2005) pumping test are used as a standard for comparison. Three variably-saturated groundwater flow numerical codes were evaluated for their ability to replicate the variations in soil moisture content observed during pumping by Bevan et al. (2005). Results of the numerical simulations were also analyzed for their similarity to the peak and subsequent decrease in vertical gradients observed during pumping in the Borden aquifer. While the models generated vertical gradients through the capillary fringe during pumping, these gradients dissipated significantly before 1000 min. of pumping. No gradients in the saturated zone generated by the numerical model would be capable of shifting the pressure head sufficiently to cause an apparent capillary fringe extension following the first few hours of pumping. Significant gradients were persistent throughout the test at locations where saturation was less than 85%. Accounting for the formation of vertical gradients, no simulation was able to replicate the soil moisture distributions observed by Bevan et al. (2005). Based on these results, heterogeneity, hysteresis, and entrapped air were proposed as processes with the potential to significantly affect drainage from above the water table during pumping, as their investigation may provide the physical mechanism for the observed capillary fringe extension. Compaction of the aquifer material was dismissed as a potential mechanism based on the results of a proctor test. The effect of heterogeneity on drainage from the Borden aquifer during pumping was investigated numerically using geostatistical methods. A log-normal saturated hydraulic conductivity distribution was used to represent the Borden aquifer. Brooks and Corey parameters were used to describe the pressure-saturation-relative conductivity relationships. The air-entry pressure parameter was scaled to the saturated conductivity using the scaling relationship for Borden sand proposed by Keuper and Frind (1991). The Brooks and Corey lambda parameter was kept constant. A Monte Carlo analysis was performed on the results. While several realizations of the hydraulic conductivity distribution resulted in the formation of perched water during drainage, the ensemble capillary fringe thickness was unchanged from the thickness generated using a homogeneous conceptual aquifer model. No single realization produced a capillary fringe extension in which the magnitude was a function of elapsed pumping time, or distance from the pumping well. Approximation of the effect of air-entry barriers on drainage did not increase the estimated capillary fringe thickness. The presence and location of finer grained layers appeared to have a much greater impact on the thickness of the capillary fringe than the drawdown induced by pumping. Ensemble results for the hydraulic head drawdown provided improved matches to the field observations in comparison to the homogeneous numerical model during intermediate and late times in the pumping test. A mild degree of heterogeneity appears to have sufficient effect on drainage from above the water table during pumping to impact hydraulic drawdown. The effect would be magnified with the greater degree of heterogeneity that is more typical of natural aquifer systems. A 24-hour pumping test was conducted at CFB Borden to gain a better understanding of the nature of drainage during a pumping test. Due to the wet site conditions prior to the test, the moisture profile during pumping was significantly influenced by hysteresis. The hydraulic head drawdown generated during the test was insufficient to generate any drainage due to the lowering of the top of the saturated zone, and the formation of perched lenses could not occur. Hysteresis in the moisture profile was a controlling factor in this result. Although there was no significant drainage initiated due to the lowering of the top of the saturated zone, an inflection point was still apparent in the time-drawdown curve for the four monitoring wells observed. Vertical gradients measured throughout the saturated zone, including the capillary fringe, remained low throughout the duration of pumping, and no significant increase was apparent in the transition from saturated to tension-saturated conditions. Hysteresis has the potential to increase the delay in drainage as the water table falls during pumping. A laboratory tank apparatus was used to determine the effect of entrapped air, grain size distribution, and horizontal gradient on drainage in a primarily horizontal flow regime. The tank was packed on three separate occasions, once with a coarse well sorted silica sand, and twice with sand from the Borden aquifer. For each packing, the tank was drained twice, using two different horizontal gradient magnitudes. Results show that horizontal gradient magnitude has no impact on soil moisture distributions during drainage. Air-entry pressure was elevated in comparison to gravity drainage derived pressure head – saturation curves. This elevation was not transient, nor dependant on gradient or grain size distribution. The increase in air-entry pressure does not appear to be due to insufficient equilibration time between water level drops or flow redistribution around the TDR Rods. Results of this study support a conceptual model of unconfined aquifer response in which drainage from above the water table is a complex and time dependant process. Individually, heterogeneity and hysteresis have been shown to cause a time delay between the lowering of the water table and the subsequent drainage of the tension saturated zone during intermediate to late pumping times. The magnitude and duration of this delay varies by process and is a function of the degree of heterogeneity, moisture conditions in the aquifer prior to pumping, and the drawdown rate of the water table. While no individual process tested could produce the capillary fringe extension observed by Bevan et al. (2005), the investigation of each has led to an improved conceptual understanding of the response to pumping in unconfined aquifers. Due to the complex interaction of these processes it is unlikely that pumping test results, even those which include moisture content observations, could be used to accurately predict unsaturated flow parameters. Storage parameter (i.e. specific yield) estimates made using analytical solutions may not be appropriate unless delayed drainage from above the water table is properly accounted for.

A patterned, partially-treed, fen in the mid-boreal region of central Saskatchewan was the site of renewed hydrological research from 2002 to 2004. Hydraulic conductivity, transmissivity, and storativity were determined through use of a surface loading test, pumping tests, and an enclosed field drainage test. None of these field tests have been previously described in the literature as having been used in peat environments. The combined results of field and laboratory drainage tests were used to obtain a general storativity with water table depth relationship in the upper peat layer. The hydraulic conductivity, measured with slug tests, the loading test, and pumping tests, is high near the surface, declining greatly with depth. These previously untested field methods have the advantage of representing volumes of peat from tenths of a meter to cubic meters. </p>Characterization of the hydrology of the peatland involved year round observations of water table, piezometric head, peat surface elevations, frost depth and peat temperatures. Fluctuations of the water table, and soil moisture changes produce changes in effective stress that lead to volume change in the highly compressible peat. This is particularly important for sites with thick peat deposits. Independent compressibility estimates were as high as 10-5 N/m2 in the upper peat. At three fen sites, changes in peat thickness were estimated from monthly estimates of effective stress change, using year round hydrological observations, and compared to measured annual peat thickness changes. Water table changes causing soil moisture changes, and freeze-thaw processes, explained the majority of peat surface movements.

Excess global elemental sulphur (So) production has resulted in a decrease in its price. As a result, many companies, such as Syncrude Canada Ltd., have resorted to above ground storage alternatives. Geochemical reactions in these above ground blocks produce elevated concentrations of H2SO4 (acid). This acid can have potentially deleterious effects on the environment. As such, these blocks will require long-term (500 years) monitoring and maintenance. Presently the So is removed from the product stream, piped in a molten state, and poured over a low permeability liner in thin lifts. As the So cools and undergoes crystal structure change it fractures, creating preferential flow passages which are potentially highly conductive. An understanding of the liquid conductivity (Kl) of the block and knowledge regarding the spatial and temporal distribution of acid (H2SO4) within these blocks is required. In this thesis, gas pumping tests were conducted on an above ground block to determine the gas flow rates within the block and to indirectly determine the Kl of the block. Measurements of the relative humidity (RH) in the block were used to observe changes in stored acid concentrations with time and location. The results of the gas conductivity (Kg) testing showed that the block is anisotropic and is highly conductive in both the horizontal and vertical directions. Cross hole tests appeared to produce the most representative estimates of Kg due to the negation of turbulence that arises in the vicinity of the borehole. The choice of gas used in the analysis had negligible effect on the resulting Kl in contrast to choice of liquid, which resulted in larger variations in Kl. The Kl was a maximum when the liquid was pure water and decreased with increasing acid strength. The geometric mean of the resulting cross hole Kl values was 2 x 10-3 m s-1 (pure water). RH measurements were observed to fluctuate with depth and increased following precipitation. The resulting minimum pH observed within the block occurred at depths of 3 and 7 meters below the surface of the So block and increased with depth. The arithmetic mean pH value based on the daily averaged RH measurements was -1.7.

A patterned, partially-treed, fen in the mid-boreal region of central Saskatchewan was the site of renewed hydrological research from 2002 to 2004. Hydraulic conductivity, transmissivity, and storativity were determined through use of a surface loading test, pumping tests, and an enclosed field drainage test. None of these field tests have been previously described in the literature as having been used in peat environments. The combined results of field and laboratory drainage tests were used to obtain a general storativity with water table depth relationship in the upper peat layer. The hydraulic conductivity, measured with slug tests, the loading test, and pumping tests, is high near the surface, declining greatly with depth. These previously untested field methods have the advantage of representing volumes of peat from tenths of a meter to cubic meters. </p>Characterization of the hydrology of the peatland involved year round observations of water table, piezometric head, peat surface elevations, frost depth and peat temperatures. Fluctuations of the water table, and soil moisture changes produce changes in effective stress that lead to volume change in the highly compressible peat. This is particularly important for sites with thick peat deposits. Independent compressibility estimates were as high as 10-5 N/m2 in the upper peat. At three fen sites, changes in peat thickness were estimated from monthly estimates of effective stress change, using year round hydrological observations, and compared to measured annual peat thickness changes. Water table changes causing soil moisture changes, and freeze-thaw processes, explained the majority of peat surface movements.

The purpose of this study is to investigate the importance of prior information about hydraulic conductivity (K) by Kriging, using point K data and/or residual covariance, on improvements of K estimates at the North Campus Research Site (NCRS). Among many methods that can characterize the mean or detail distribution of hydraulic conductivity (K), the Cooper-Jacob straight line solution, Kriging using point K data, single-well pumping tests inversion and Hydraulic Tomography (HT) have been compared in this study, using the head data collected from 15 cross-hole pumping tests collected at NCRS, where 9 existing wells were installed with packer system and the pressure responses at different intervals in different wells were monitored with transducers. It is found that the HT method, which fuse all the available pumping test data, yields more accurate and consistent results. However, many studies have indicated that the hydraulic data combined with geologic investigation will improve the HT estimates. Thus, in this study, hard data of K obtained by permeameter (227 data points) are brought in using Kriging and combined with HT to yield better estimate K field. Moreover, the validations of unused tests indicate that the estimated K obtained using collected K information makes more accurate predictions.

Η λεκάνη του ποταμού Γλαύκου εκτείνεται επί των δυτικών κλιτύων του Παναχαϊκού, στο ΒΔ/κό τμήμα του νομού Αχαΐας, NA/κά της πόλης των Πατρών καταλαμβάνοντας συνολική έκταση 101,67 Km2 και αποτελεί την κύρια πηγή κάλυψης των υδατικών αναγκών της. Χαρακτηρίζεται από μέτρια ανάπτυξη υδρογραφικού δικτύου δενδριτικού τύπου αποστράγγισης και κατά συνέπεια υψηλή διαπερατότητα των πετρωμάτων και σημαντική κατείσδυση, σε βάρος της επιφανειακής απορροής. Οι σπουδαιότεροι από τους χείμαρρους που διαρρέουν την περιοχή έρευνας είναι ο Ξηροπόταμος, ο Φίλιουρας, η Σούτα, του Βερβενίου και το Ελεκιστριάνικο, οι οποίοι συμβάλουν εντός του Γλαύκου. Το αλπικά πτυχωμένο υπόβαθρο της λεκάνης περιλαμβάνει μια ακολουθία προορογενετικών ιζημάτων (πελαγικοί ασβεστόλιθοι, ραδιολαρίτες, κ.α.) της ζώνης Πίνδου, και μια συνορογενετική κλαστική ακολουθία (φλύσχης), που αποτελείται από εναλλαγές ιλυολίθων, ψαμμιτών και σπανιότερα κροκαλοπαγών. Τα στρώματα της ζώνης Πίνδου αναδύθηκαν με την τελική φάση των πτυχώσεων στο Κάτω Ολιγόκαινο, όπου έλαβε χώρα η επώθηση της Πίνδου, υπό μορφή καλύμματος, πάνω στη ζώνη Γαβρόβου – Τριπόλεως. Τα μέτωπα των επωθήσεων μεταξύ των λεπιών και οι άξονες των πτυχώσεων έχουν διεύθυνση ΒΔ – ΝΑ με κατεύθυνση της κίνησης από τα ανατολικά προς τα δυτικά και άμεση σχέση με την πλειονότητα των καρστικών πηγών. Στην περιοχή του Πατραϊκού κόλπου επικρατεί ένα ρομβοειδές σύστημα ρηγμάτωσης με μεγάλης κλίσης και ΑΒΑ/κής και ΔΒΔ/κής διεύθυνσης κανονικά ρήγματα που δημιουργεί ένα μωσαϊκό κατατεμαχισμένων τεκτονικών μπλοκ και μια γενική ανύψωση της περιοχής που συνεχίζεται μέχρι σήμερα. Τη διάνοιξη των κοιλάδων της ευρύτερης περιοχής έρευνας, η οποία συχνά συνοδεύεται από κατολισθήσεις, την καθορίζουν 4 δέσμες νεοτεκτονικών ρηγμάτων, ΒΔ/κής, ΒΑ/κής, ΔΒΔ/κής, και ΒΒΑ/κής διεύθυνσης. Το Πλειοτεταρτογενές επικάλυμμα που εμφανίζεται στην παράκτια και λοφώδη περιοχή αποτελείται από δύο λιθοστρωματογραφικές ενότητες. Η κατώτερη συνίσταται από αργίλους και άμμους, που αποτέθηκαν σε ένα λιμναίο έως υφάλμυρο περιβάλλον ιζηματογένεσης κατά τη διάρκεια του Πλειόκαινου έως το Κατώτερο Πλειστόκαινο και η ανώτερη από Καλάβριας ηλικίας δελταϊκά και χερσαία κροκαλοπαγή. Γενικά οι προσχώσεις χαρακτηρίζονται από λιθολογική ανομοιομορφία τόσο κατά την κατακόρυφη όσο και κατά την οριζόντια διεύθυνση και το πάχος τους παρουσιάζει βαθμιαία αύξηση από τα βορειότερα και νοτιότερα όρια προς το κεντρικό τμήμα της λεκάνης, όπου και υπερβαίνει τα 200 μ. Το ετήσιο ύψος βροχόπτωσης (1071 mm) στην περιοχή έρευνας είναι αρκετά υψηλό για τα δεδομένα της χώρας μας και κυμαίνεται από 640 – 900 mm στις πεδινές περιοχές, ενώ στις ορεινές περιοχές φθάνει τα 1560 mm. Τα τελευταία χρόνια παρουσιάζεται μια εποχιακή μετακίνηση των βροχοπτώσεων από τον χειμώνα προς την άνοιξη και το φθινόπωρο, η οποία συνεπάγεται απώλεια του διαθέσιμου νερού της ενεργής κατείσδυσης, λόγω αυξημένης εξατμισοδιαπνοής. Από υδρολογικής άποψης η λεκάνη του Γλαύκου δέχεται ετησίως κατά μέσο όρο 108,89 106 m3 νερού από βροχόπτωση, εκ’ των οποίων ποσοστό 48,9 % επανέρχεται στην ατμόσφαιρα με τις διαδικασίες της εξάτμισης και διαπνοής, 28,6 % απορρέει επιφανειακά και 22,5 % κατεισδύει, κυρίως σε σημαντικούς από υδρογεωλογική άποψη σχηματισμούς (ασβεστόλιθους και τεταρτογενείς αποθέσεις). Χαρακτηριστικό υδρογεωλογικό γνώρισμα της περιοχής έρευνας αποτελούν οι ημιαυτόνομες υδρογεωλογικά καρστικές ενότητες, που αναπτύσσονται λόγω της λεπιοειδούς και ρηξιγενούς τεκτονικής στην περιοχή και διαφοροποιούν την κίνηση του υπόγειου νερού. Σχετικά με τις προσχωματικές αποθέσεις του Τεταρτογενούς ο ελεύθερος υδροφόρος ορίζοντας της ανώτερης ζώνης κάμπτεται προοδευτικά και μεταπίπτει σε επάλληλους υπό πίεση υδροφόρους ορίζοντες στην παράκτια ζώνη. Στις αρχές της δεκαετίας του ’90 στην παράκτια περιοχή, λόγω της υπεράντλησης, διαπιστώθηκαν αρνητικές τιμές της πιεζομετρικής επιφάνειας σε απόσταση έως 3 Κm από την ακτή, με συνέπεια την αλμύρινση του προσχωματικού υδροφόρου από τη διείσδυση της θάλασσας. Η μείωση των αντλήσεων στα μέσα της δεκαετίας του ’90 οδήγησαν στην άνοδο των πιεζομετρικών στάθμεων και στην επανεμφάνιση φαινομένων αρτεσιανισμού των γεωτρήσεων της παράκτιας ζώνης. Από την επεξεργασία των αντλητικών δεδομένων διαπιστώθηκε η εμφάνιση υψηλών τιμών του συντελεστή της υδραυλικής αγωγιμότητας τόσο στους προσχωματικούς υδροφόρους της παράκτιας ζώνης, όσο και στους καρστικούς σχηματισμούς. Μικρότερες ταχύτητες κίνησης του υπόγειου νερού εμφανίζουν οι υδροφόροι των αποθέσεων του Νεογενούς, αλλά και των προσχώσεων της νότιας όχθης του ποταμού Γλαύκου σε σχέση με αυτούς της βόρειας όχθης, λόγω της επικράτησης των λεπτομερών έναντι των αδρομερών υλικών. Ο σημαντικότερος παράγοντας τροφοδοσίας του προσχωσιγενή υδροφόρου της λεκάνης του Γλαύκου είναι η πλευρική τροφοδοσία κατά μήκος της κοίτης του ποταμού και εν’ συνεχεία αυτός της πλευρικής τροφοδοσίας από τους ασβεστόλιθους, ενώ λιγότερο σημαντικοί εμφανίζονται οι παράγοντες του απευθείας κατεισδύοντος νερού από τις βροχοπτώσεις και από το περίσσευμα του προς αρδευτική χρήση νερού. Με βάση το ισοζύγιο εισροών – εκροών των προσχωματικών υδροφόρων της λεκάνης του Γλαύκου, για τα υδρολογικά έτη 1999 – 2002 προέκυψε μέσο ετήσιο πλεόνασμα 6,5*106 m3 νερού. Γενικά, αν εξαιρεθεί η παράκτια ζώνη της λεκάνης του Γλαύκου, η ποιότητα του νερού των προσχωσιγενών υδροφόρων, καθώς και των νεογενών αποθέσεων, αλλά και των καρστικών σχηματισμών της λεκάνης, κρίνεται καλή. Στην πλειονότητά τους τα υπόγεια νερά, όπως και τα επιφανειακά και τα πηγαία, εμφάνιζαν τον τύπο Ca-HCO3, που περιλαμβάνει γενικά νερά με καλή τροφοδοσία και ανανέωση κυρίως κατά μήκος των αξόνων αποστράγγισης. Η χωροχρονική μετακίνηση της ζώνης υφαλμύρινσης στην παράκτια ζώνη, την περίοδο 1999 – 2002, διαπιστώθηκε εκτός από την αυξημένη κατανομή διάφορων ιόντων και με την χρησιμοποίηση των συντελεστών S.A.R., Revelle και Schoeller, αλλά και των λόγων rBr-/rCl- και rBr-/rI-. Στη διάρκεια της περιόδου 1999 – 2002, προέκυψε μια αισθητή μείωση της ρύπανσης από τη διείσδυση θαλασσινού νερού στην παράκτια περιοχή. Σημαντικό ρόλο στην επιτάχυνση του ρυθμού της αποκατάστασης των παράκτιων υδροφόρων της λεκάνης του Γλαύκου διαδραμάτισε η πληθώρα γεωτρήσεων αυτόματης ροής στην παράκτια ζώνη, οι οποίες παροχετεύουν περί τα 3,5*106 m3 ρυπασμένου νερού, σε ετήσια βάση, προς τη θάλασσα. Η θέση και η χωροχρονική μετακίνηση της ζώνης υφαλμύρινσης στην παράκτια ζώνη διαπιστώθηκε επίσης από γεωηλεκτρικές έρευνες που πραγματοποιήθηκαν με τις διατάξεις Schlumberger, Wenner – Schlumberger και Pole – Pole. Από τη γεωηλεκτρική έρευνα διαπιστώθηκε ότι η διείσδυση του υφάλμυρου νερού σπανίως εμφανίζεται με τη μορφή μετώπου, αλλά ακολουθεί επιλεκτικές οδούς μέσω των αδρομερέστερων σχηματισμών, ενώ οι λεπτομερείς αργιλικοί σχηματισμοί παίζουν τον ρόλο υδραυλικού φραγμού. Τέλος, με τη μέθοδο της σεισμικής ανάκλασης προσδιορίστηκαν η γεωμετρία και το βάθος συνάντησης του υποβάθρου στην παράκτια ζώνη. Επισημαίνεται η ανάγκη τεχνητού εμπλουτισμού του προσχωσιγενή υδροφόρου ορίζοντα με τις χειμερινές απορροές του Γλαύκου για την ταχύτερη αποκατάσταση της ποιότητας του νερού και την αύξηση του υδατικού δυναμικού της λεκάνης. Εφαρμόστηκε η μέθοδος DRASTIC για την εκτίμηση της τρωτότητας των υπόγειων νερών απέναντι σε εξωτερική ρύπανση, όπου με βάση τις τιμές του δείκτη DRASTIC κατασκευάστηκε χάρτης τρωτότητας της περιοχής. Περιοχές υψηλής τρωτότητας εντοπίζονται στο παράκτιο τμήμα του υδροφορέα, ενώ αντίθετα περιοχές μέσης τρωτότητας στο Α/κό τμήμα του υδροφορέα. Τέλος, κατασκευάστηκε μαθηματικό ομοίωμα των υδροφορέων της προσχωματικής λεκάνης του Γλαύκου με την εφαρμογή του κώδικα MODFLOW παρέχοντας έτσι ένα όσο το δυνατόν πιο αξιόπιστο πρότυπο διαχείρισης του υπόγειου υδατικού δυναμικού της περιοχή έρευνας. / The Glafkos’ river basin is extended on the west side of the Panaxaikon mountain in the northwest area of the prefecture of Achaia, southeast of the city of Patras, occupying a total extent of 101,67 Km2 and constituting the main source of Patras’ water needs. It is characterized by the mediocre growth of the hydrographical network (a dendrite type of draining) and consequently the high permeability of rocks and the important infiltration at the expense of the runoff. The most important torrents that flow through the region of research are Xiropotamos, Filiouras, Souta, Verveniou and Elekistrianiko, which contribute inside the Glafkos River. The Alpine folded basin’s basement includes a sequence of pre-orogenetic sediments (marine limestone, radiolarites, etc) of the Pindos zone, and a clastic orogenetic sequence (flysch), which is constituted by alternations of silt rocks, sandstones and rarely conglomerates. The layers of the Pindos zone emerged at the final phase of the folding tectonics in the Lower Oligocene, where the Pindos’ thrust occurred in the form of a nappe, above the Gavrovo – Tripolitsa zone. The foreheads of the thrusts between the slices as well as the axes of folds have a NW – SE direction, with the direction of movement from east to west, and have a direct relation to the majority of the karstic springs. In the region of Patraikos Gulf, what prevails is a rhomboid faulting system with high slope and ENE, WNW directed normal faults that create a mosaic of fragmentized tectonic blocks and a general rising of region that continues until today. The opening up of the valleys in the wider region of research, which is often accompanied by landslides, is determined from 4 bunches of neotectonic faults directed NW, NE, WNW and NNE. The Plio-quaternary cover that appears in the coastal and hilly region is constituted by two stratigraphical units. The lower one consists of clays and sands, which were deposited in a lacustrine to brackish environment of sedimentation during the Pliocene to the Lower Pleistocene and the upper one consists of Calabria dating from the deltaic and land conglomerates. Generally the alluvium deposits are characterized by lithological heterogeneity both at the vertical and the horizontal direction and their thickness presents a gradual increase from the northerner and southerner limits to the central department of the basin, which exceeds 200 m. The annual height of rainfall (1071 mms) in the region of research is quite high for our country’s data and fluctuates from 640 to 900 mms in flat regions, whereas in the mountainous regions it reaches 1560 mms. During the last years, what takes place is a seasonal displacement of rainfall from winter to spring and autumn, which leads to the loss of the available water of the active infiltration because of increased evaporotranspiration. From a hydrologic aspect, the Glafkos basin receives annually, on average, 108,89 106 m3 of the water from rainfall, from which 48,9 % comes back to atmosphere with the processes of evaporation and transpiration, 28,6 % rises on the surface and 22,5 % infiltrates, mainly in important, from a hydrogeological aspect, formations (limestones and quaternary depositions). The semi-independent hydrogeologically karstic units, which are developed because of the laminated and faulty tectonics in the region and differentiate the movement of groundwater, constitute a characteristic hydrogeological feature of the region of research. In relation to the alluvium deposits, the unconfined aquifer of the superior area is progressively bent and falls into successive under pressure (confined) aquifers in the coastal area. At the beginning of the ‘90s in the coastal region, because of the overpumping, negative values of the piezometric surface in a distance up to 3 Km from the coastline were realised, having as a consequence the salinity of coastal alluvium aquifer from the seawater intrusion. The reduction of pumping in the middle of the ‘90s led to the rise of piezometric levels and to the reappearance of the phenomena of artesian wells in the coastal area. Due to the elaboration of the pumping data, what was realised is the appearance of high values of the hydraulic conductivity’s factor in the alluvium aquifers of the coastal zone as well as in the karstic aquifers. The aquifers of the Neogene formations as well as the alluvium aquifers of the southern bank of the river Glafkos present a smaller speed of movement of groundwater as compared to those of the northern bank, because of the predominance of the fine-grained clastics. The most important factor of the recharge of the Glafkos’ basin alluvium aquifer is basically the costal recharge from the river bank and then follows the inductive recharge from the limestones, whereas the direct infiltrated water from the rainfall and from the surplus of the irrigation water seem to be the least important factors. Based on the balance of the inflows – outflows of the Glafkos’ basin alluvium aquifer, an average annual surplus of 6,5*106 m3 of water has resulted, during the hydrologic years 1999 –2002. Generally, the quality of water in the alluvium aquifers as well as in the aquifers of Neogene formations, but also that in the karstic aquifers is considered to be good, if the coastal area of the Glafkos’ basin is excluded. Most of the groundwater, as well as the surface and spring water, presented the geochemical type Ca-HCO3, which generally includes water of good recharge and renewal, mainly along the drainage axes. The time-space movement of the brackish zone in the coastal area, in the period 1999 –2002, was realised not only by the increased distribution of various ions but also by the utilisation of factors S. A. R., Revelle and Schoeller, as well as the ratios rBr-/rCl- and rBr-/rI-. During the period 1999 – 2002, a perceptible reduction of the pollution from the saline intrusion in the coastal region took place. The abundance of wells of automatic flow into coastal area, which drain 3,5*106 m3 of brackish water, annually, to the sea played an important role in the acceleration of the restoration of the coastal basin aquifers of the river Glafkos. The position and the time-space movement of the brackish zone in the coastal area was realised also by geoelectrical researches that took place with the dispositions Schlumberger, Wenner – Schlumberger and Pole – Pole. Geoelectrical research revealed that seawater intrusion rarely appears in the form of a forehead, but follows selective paths via the coarse-grained clastics, while the fine-grained clastic formations play the role of a hydraulic barrier. Finally, the geometry and the depth of the basement in the coastal area were determined with the application of the seismic reflection method. The need of artificial enrichment of the alluvium aquifer from the wintry flows of the Glafkos River is pointed out, for a more rapid restoration of the water quality and the increase of the Glafkos’ basin water potential. The DRASTIC method was applied for the estimation of the vulnerability of the groundwater towards exterior pollution, where based on the DRASTIC indicator’s values, a map of the vulnerability of the region of research was constructed. Areas of high vulnerability are located in the coastal part of the aquifer, while areas of medium vulnerability are located in the eastern part of the basin. Finally, a mathematic model of the Glafkos’ basin alluvium aquifers was constructed with the application of code MODFLOW, thus providing an as much as possible reliable model of the management of the Glafkos’ basin groundwater potential.

O principal objetivo deste trabalho foi avaliar um procedimento de campo para testar o comprimento mínimo que fraturas devem ter para construir uma rede de fluxo em escala de dezenas de metros ao longo de maciços cristalinos. O comprimento mínimo é determinado a partir do limite de percolação, definido por modelos baseados na Teoria da Percolação e a densidade de fraturas no poço, determinada pela perfilagem ótica. Para testar o valor de 3,9 metros que foi encontrado, foram realizados bombeamentos em dois poços próximos enquanto o nível estático era registrado no poço de observação. O método apresenta facilidades em termos de operação e para obter-se o número de fraturas que interceptam o poço, no entanto o registro do nível estático é afetado por fatores externos, como presença de efeitos de maré e variação da pressão atmosférica, e correções são necessárias para permitir identificar a interferência proveniente somente do bombeamento. / The objective of this work is to develop a field procedure to determine a minimum characteristic length forming a connected fracture network in crystalline rocks. This minimum length is determined as a percolation threshold defined by models based on Percolation Theory and fracture density data determined from borehole imaging with well-logging probes. The characteristic length (3.9 meters) once estimated for a testing well was evaluated by monitoring its water head meanwhile nearby wells at different distances were pumped. The water head variation recorded in the testing well was disturbed by interfering effects associated to earth tides and atmospheric pressure, requiring further corrections to isolate effects induced by pumping. The results of these tests validate the percolation limit determined from logging data suggesting a rock mass with very low connectivity. The proposed test can be regarded as simple and easy to apply in many practical situations, for example when evaluating groundwater resources or geotechnical properties in fractured crystalline rocks.

O principal objetivo deste trabalho foi avaliar um procedimento de campo para testar o comprimento mínimo que fraturas devem ter para construir uma rede de fluxo em escala de dezenas de metros ao longo de maciços cristalinos. O comprimento mínimo é determinado a partir do limite de percolação, definido por modelos baseados na Teoria da Percolação e a densidade de fraturas no poço, determinada pela perfilagem ótica. Para testar o valor de 3,9 metros que foi encontrado, foram realizados bombeamentos em dois poços próximos enquanto o nível estático era registrado no poço de observação. O método apresenta facilidades em termos de operação e para obter-se o número de fraturas que interceptam o poço, no entanto o registro do nível estático é afetado por fatores externos, como presença de efeitos de maré e variação da pressão atmosférica, e correções são necessárias para permitir identificar a interferência proveniente somente do bombeamento. / The objective of this work is to develop a field procedure to determine a minimum characteristic length forming a connected fracture network in crystalline rocks. This minimum length is determined as a percolation threshold defined by models based on Percolation Theory and fracture density data determined from borehole imaging with well-logging probes. The characteristic length (3.9 meters) once estimated for a testing well was evaluated by monitoring its water head meanwhile nearby wells at different distances were pumped. The water head variation recorded in the testing well was disturbed by interfering effects associated to earth tides and atmospheric pressure, requiring further corrections to isolate effects induced by pumping. The results of these tests validate the percolation limit determined from logging data suggesting a rock mass with very low connectivity. The proposed test can be regarded as simple and easy to apply in many practical situations, for example when evaluating groundwater resources or geotechnical properties in fractured crystalline rocks.

Dans un champ captant, comme celui qui alimente l'agglomération lyonnaise, le fonctionnement de chaque « objet » (bassins d'infiltration, puits, rivières, nappe, zone non saturée) et leurs interactions sont complexes et mal connus. Dans un premier temps, une série d'essais d'infiltration à différentes échelles dans un bassin artificiel de réalimentation a permis de mieux appréhender le fonctionnement de cet ouvrage et de chiffrer les paramètres hydrodynamiques de la zone non saturée. Les résultats des interprétations par méthodes numériques fondées sur l'équation de Richards ont montré que les flux infiltrés dans les bassins dépendent principalement de la conductivité hydraulique à saturation d'une couche située directement sous le sable calibré couvrant le fond du bassin, identifiée comme étant moins perméable que la nappe. Cette couche conditionne l'existence d'une zone non saturée. La réalisation d'essais de pompage dans l'aquifère sur les forages d'exploitation et sur un dispositif spécialement mis en place durant ce travail a permis de déterminer les paramètres hydrodynamiques de la nappe. Une analyse des observations et une modélisation conceptuelle en 2D, puis en 3D ont permis d'identifier les mécanismes prépondérants (stratifications, apports et prélèvements) et de simuler correctement à la fois les flux infiltrés dans un des bassins d'infiltration et la remontée de la nappe. A l'échelle d'un bassin, les flux infiltrés sont variables dans le temps, ils dépendent de l'état de colmatage de la surface d'infiltration mais également de la température de l'eau infiltrée et de l'état hydrique initial du sol sous le bassin. Les analyses de sensibilité réalisées avec les modèles mis en place indiquent que la conductivité hydraulique à saturation de l'aquifère, mais également la proximité des conditions aux limites imposées dans la nappe (les rivières et les puits de pompage) influencent de manière prépondérante la remontée de la nappe. Une modélisation 3D d'un autre secteur du champ captant comprenant deux bassins d'infiltration, deux bras de rivière ainsi que des puits de pompage a été réalisée. La condition à la limite imposée sur les rivières est du troisième type en accord avec l'observation d'un sous-écoulement en nappe. Les échanges nappe/rivières sont calés sur des observations à partir d'une chronique de propagation d'une onde de crue dans la nappe. Des piézomètres en flûte de pan, spécifiquement implantés à proximité d'un bassin, ont permis d'observer des différences de charge hydraulique fortes à différents niveaux de l'aquifère lorsque le bassin d'infiltration est en eau. La modélisation 3D est conforme à ces observations. Elle a confirmé l'importance du rôle d'une hétérogénéité de type argilo-sableuse (de conductivité hydraulique à saturation inférieure aux autres lithologies présentes dans l'aquifère) dans les écoulements (direction et flux). Le modèle développé représente correctement les flux infiltrés via les bassins ainsi que les fluctuations de la piézométrie de la nappe. Il permet de vérifier l'inversion des écoulements par rapport aux infiltrations de la rivière, d'identifier les puits alimentés par les bassins d'infiltration et également de mettre en évidence les flux de nappe passant sous la rivière. / In a well field of the Lyon metropolitan area, designed for drinking water supply, behaviour of each object (infiltration basins, wells, rivers, aquifer, and unsaturated zone) and their interactions are complex and not well-known. As a first step, infiltration tests at different spatial scales in one artificial basin were performed to better understand the basin operation and to estimate the hydrodynamic parameters of the unsaturated zone. Results of interpretation, using numerical methods based on Richards equation, reveal that infiltrated basin fluxes mainly depend on saturated hydraulic conductivity of a layer located just below the calibrated sand layer that cover the basin bottom. Indeed this layer has been estimated to be less permeable than the aquifer, which allows the existence of the unsaturated zone below. Pumping tests in the groundwater have been performed using production wells and a well specially implemented during this thesis work in order to estimate aquifer hydrodynamic parameters. Observations analysis and a conceptual modelling, in 2D and then in 3D, lead to a better understanding of the controlling mechanisms (stratification, input and output) and to simulate both basin infiltration rates and water table rise. Considering the whole basin scale, input fluxes are transient, related to the clogging statement of the infiltration area but also to the temperature of inflow water and the initial statement of the soil just below the basin. Sensibility analyses using the models highlight that the amount of the water table rise is mainly influenced by the aquifer saturated hydraulic conductivity and also by the location of imposed boundaries in the aquifer (rivers and pumping wells). The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flows below the river. A 3D modelling has been realised in another area of the well field, comprising two infiltration basins, two river arms and pumping wells. In agreement with underflow in the aquifer, rivers are imposed in the model as third kind boundary conditions. Aquifer and river exchanges are calibrated with observed data of one aquifer flood-wave propagation. Significant differences of hydraulic heads have been observed at different depths of the aquifer using panpipes piezometers, specifically implemented, close to one infiltration basin. Theses differences are closely related to basin operation. These observations are properly calculated by the 3D model. Using the model, the effect of one sandy-clay heterogeneous layer (whose saturated hydraulic conductivity is lower than the ones of other aquifer lithologies) on aquifer flows (direction and flux) is notable. The model properly accounts basin inflow fluxes and water table fluctuations. The model is able to verify if flows are reversed in relation to river exchanges, if wells are fed by infiltration basins and it highlights aquifer flow below the river.