Semi-arid regions, like the Okanagan Basin of British Columbia, Canada, are often faced with the difficulty of managing limited groundwater and surface water resources while accommodating rapid population growth and increasing land development. In the South Okanagan Basin, a better understanding of groundwater recharge sources, groundwater availability and susceptibility of water supplies to anthropogenic contamination is needed to best direct and protect the regions water resources. The purpose of this study was: (1) to characterize the regional hydrogeological setting of the South Okanagan Basin by establishing an isotopic and geochemical framework that included precipitation and surface waters of the Okanagan Basin and groundwaters of the South Okanagan Basin; and (2) to characterize nitrate contamination and its sources in shallow groundwaters of the Osoyoos area. Stable isotopes of water, nitrate and dissolved oxygen, groundwater chemistry, water levels and enriched tritium, tritium/helium and/or radiocarbon age dating techniques were used. Two provisional local meteoric water lines were established for the Okanagan Basin: &delta2H=6.06&delta18O31.21 (Osoyoos) and &delta2H=7.03&delta18O-12.68 (West Kelowna). Surface waters of the Okanagan River system were sources of irrigation water in the South Okanagan Basin valley and irrigation-return flow was the primary source of recharge for shallow groundwaters. Fractured bedrock in highlands east and west of the valley were not a significant source of recharge for shallow valley groundwater, however, may recharge deeper, or basal, valley deposits. As irrigation-return flow controls shallow groundwater dynamics in the valley sediments, groundwater quality is susceptible to anthropogenic contamination. In Osoyoos, nitrate was present in shallow groundwaters at concentrations of up to 24.4 mg/l N as a result of fertilizer nitrogen applied at the soil surface, mostly at orchards. Two agricultural drainage systems in north Osoyoos discharge roughly 1,900 kg N/year from nitrate-contaminated groundwater directly into Osoyoos Lake and may contribute in part to its eutrophication.

Many industrial activities discharge sulphate- and metal-containing wastewaters, including the manufacture of pulp and paper, mining and mineral processing, and petrochemical industries. Acid mine drainage (AMD) is an example of such sulphate- and metal-containing waste streams. Formation of AMD is generally the result of uncontrolled oxidation of the sulphide minerals present in the terrain in which the drainage flows with concomitant leaching of the metals. Acid mine drainage (AMD) and other sulphate- and metal-containing waste streams are amenable to active biological treatment. Anaerobic reduction of sulphate, reaction of produced sulphide with metal ions present in the waste stream, and biooxidation of excess sulphide are three main sub-processes involved in the active biotreatment of AMD. Anaerobic reduction of sulphate can be achieved in continuous stirred tank bioreactors with freely suspended cells or in immobilized cell bioreactors. The application of freely suspended cells in a continuous system dictates a high residence time to prevent cell wash-out, unless a biomass recycle stream is used. In an immobilized cell system biomass residence time becomes uncoupled from the hydraulic residence time, thus operation of bioreactor at shorter residence times becomes possible. In the present work, kinetics of anaerobic sulphate reduction was studied in continuous immobilized cell packed-bed bioreactors. Effects of carrier matrix, concentration of sulphate in the feed and sulphate volumetric loading rate on the performance of the bioreactor were investigated. The bioreactor performance, in terms of sulphate reduction rate, was dependent on the nature of the carrier matrix, specifically the total surface area which was provided by the matrix for the establishment of biofilm. Among the three tested carrier matrices, sand displayed the superior performance and the maximum volumetric reduction rate of 1.7 g/L-h was achieved at the shortest residence time of 0.5 h. This volumetric reduction rate was 40 and 8 folds faster than the volumetric reduction rates obtained with glass beads (0.04 g/L-h; residence time: 28.6 h) and foam BSP (0.2 g/L-h; residence time: 5.3 h), respectively. Further kinetic studies with sand as a carrier matrix indicated that the extent of volumetric reduction rate was dependent on the feed sulphate concentration and volumetric loading rate. At a constant feed sulphate concentration, increases in volumetric loading rate caused the volumetric reduction rate to pass through a maximum, while increases in feed sulphate concentrations from 1.0 g/L to 5.0 g/L led to lower volumetric reduction rates. The maximum volumetric reduction rates achieved in the bioreactors fed with initial sulphate concentration of 1.0, 2.5 and 5.0 g/L were 1.71, 0.82 and 0.68 g/L-h, respectively. The coupling of lactate utilization to sulphate reduction was observed in all experimental runs and the rates calculated based on the experimental data were in close agreement with calculated theoretical rates, using the stoichiometry of the reactions involved. The maximum volumetric reduction rates achieved in the immobilized cell bioreactors were significantly faster than those reported for freely suspended cells employed in the stirred tank bioreactors.

Combustion assisted gravity drainage (CAGD) is an integrated horizontal well air injection process for recovery and upgrading of heavy oil and bitumen from tar sands. Short-distance air injection and direct mobilized oil production are the main features of this process that lead to stable sweep and high oil recovery. These characteristics identify the CAGD process as a high-potential oil recovery method either in primary production or as a follow-up process in reservoirs that have been partially depleted. The CAGD process combines the advantages of both gravity drainage and conventional in-situ combustion (ISC). A combustion chamber develops in a wide area in the reservoir around the horizontal injector and consists of flue gases, injected air, and mobilized oil. Gravity drainage is the main mechanism for mobilized oil production and extraction of flue gases from the reservoir. A 3D laboratory cell with dimensions of 0.62 m, 0.41 m, and 0.15 m was designed and constructed to study the CAGD process. The combustion cell was fitted with 48 thermocouples. A horizontal producer was placed near the base of the model and a parallel horizontal injector in the upper part at a distance of 0.13 m. Peace River heavy oil and Athabasca bitumen were used in these experiments. Experimental results showed that oil displacement occurs mainly by gravity drainage. Vigorous oxidation reactions were observed at the early stages near the heel of the injection well, where peak temperatures of about 550ºC to 690ºC were recorded. Produced oil from CAGD was upgraded by 6 and 2ºAPI for Peace River heavy oil and Athabasca bitumen respectively. Steady O2 consumption for both oil samples confirmed the stability of the process. Experimental data showed that the distance between horizontal injection and production wells is very critical. Close vertical spacing has negative effect on the process as coke deposits plug the production well and stop the process prematurely. CAGD was also laboratory tested as a follow-up process. For this reason, air was injected through dual parallel wells in a mature steam chamber. Laboratory results showed that the process can effectively create self-sustained combustion front in the previously steam-operated porous media. A maximum temperature of 617ºC was recorded, with cumulative oil recovery of 12% of original oil in place (OOIP). Post-experiment sand pack analysis indicated that in addition to sweeping the residual oil in the steam chamber, the combustion process created a hard coke shell around the boundaries. This hard shell isolated the steam chamber from the surrounding porous media and reduced the steam leakage. A thermal simulator was used for history matching the laboratory data while capturing the main production mechanisms. Numerical analysis showed very good agreement between predicted and experimental results in terms of fluid production rate, combustion temperature and produced gas composition. The validated simulation model was used to compare the performance of the CAGD process to other practiced thermal recovery methods like steam assistance gravity drainage (SAGD) and toe to heel air injection (THAI). Laboratory results showed that CAGD has the lowest cumulative energy-to-oil ratio while its oil production rate is comparable to SAGD.

An acid rock drainage (ARD) stream emanating from the Zn-Pb XY-deposit in the Yukon Territory was examined in order to evaluate the physico-chemical and geochemical processes governing the distribution of dissolved elements from the creek. The creek showed very high concentrations of metals (300 mg/L Fe, 500 mg/L Zn, 15 000 µg/L Ni, 1300 µg/L Cu and 4500 µg/L Cd), low water temperatures (1 – 12°C) and was acidic to moderately acidic (pH 3.1 – 5.0). It was found that this stream experienced a strong seasonal evolution, with increased sulphate and metal concentrations and decreased pH over the course of the summer. The mineral precipitates that formed under low pH conditions were a mixture of schwertmannite, goethite, jarosite and barite, while those that formed under moderately acidic conditions were a mixture of jurbanite, hydrobasaluminite, gibbsite and an X-ray amorphous Al-sulphate phase. Most of the mineral precipitates were of inorganic origin, although microbes may have played a role in mineral formation and trace metal sequestration in some of the precipitates. All of the mineral precipitates contained anomalous concentrations of trace elements (up to 1.5 % wt Zn) and showed a seasonal evolution in their mineralogy, both of which were determined to be a function of the pH and prevailing geochemical conditions. The geochemistry of the ARD creek draining the XY-deposit was compared to another ARD creek in the area that was likely draining shales. The two creeks were compared in order to determine if ARD geochemical characteristics can be used as a tool for the mineral exploration industry.

En presente trabajo se estudian las condiciones de servicio, así como el proceso que ocurre al producirse la rotura del suelo en cargas rápidas sobre arcillas: a) Elaboración de un modelo elasto-plástico, en el cual se reproduzca la plastificación progresiva del material, definiendo un nuevo criterio de rotura que pueda incluir los factores más representativos del comportamiento de la arcilla, incluso la anisotropía y la heterogeneidad de la misma que no eran considerados anteriormente. b) Introducción de este modelo reológico en un nuevo modelo de elementos finitos. De entre las diferentes posibilidades se ha elegido un modelo híbrido en tensiones y deformaciones, para lo cual partiendo del principio variacional de REISSNER, se ha generalizado para estudiar la fase plástica. La discretización se ha efectuado con los elementos triangulares y cuadrangulares híbridos. c) Se aplica el modelo en una zapata en faja indefinida actuando sobre una capa de arcilla deformable sobre una base rocosa rígida con interfaz lisa, variándose todos los parámetros que en él intervienen y deducción de una serie de conclusiones sobre la influencia de los factores estudiados en el comportamiento de la arcilla. / In this paper we study the conditions of service, and the process that occurs at ground breaking in fast load on clays: a) Development of elastic-plastic model in which to play the pushover of the material, defining a new failure criterion which may include factors represent the behavior of the clay, including the anisotropy and heterogeneity of the same were not considered previously. b) Introduction of the rheological model in a new finite element model. Among the different possibilities we have chosen a hybrid model stresses and strains for which starting from the Reissner variational principle has been generalized to study the plastic phase. The discretization was made with triangular and quadrangular elements hybrids. c) Model was applied in a strip footing on indefinite acting on a layer of deformable clay on a rock hard smooth interface, by varying all the parameters involved in it and deduction of a number of conclusions about the influence of the factors studied the behavior of the clay.

L’anomenat drenatge àcid de mina (AMD) ve generat per l’oxidació de sulfurs i és causa major de contaminació d’aigües a nivell mundial. L’arsènic és un del princiapls contaminants laconcentració del qual pot assolir centenars de mgL-1, és a dir, de 5 a 6 ordres de magnitud més gran que el límit de potabilitat per a l’aigua (10μg L-1) establert per la UE en 1998. En aquesta tesi, s’estudia l’impacte de la mobilització de l’arsènic al llarg de descàrregues de drenatge àcid de mina. L’oxidació de sulfurs que contenen arsènic (tal com l’arsenopirita (AsFeS), la pirita rica en arsènic (FeS2) o la marcassita (FeS2) és una de les principals fonts d’alliberament d’arsènic a l’aigua. En la primera part de la tesi, s’ha estudiat la cinètica de dissolució de l’arsenopirita i de la marcassita a pHs àcids i neutre, utilitzant reactors de flux continu, i s’han valorat els efectes del pH, de l’oxigen dissolt i de la temperatura en la dissolució d’ambdós sulfurs. A partir de les velocitats en estat estacionari establertes, es proposen les respectives lleis de dissolució que tenen en compte el lleu i el fort efecte del pH i de l’oxigen dissolt, respectivament, en llur dissolució. La incorporació d’aquestes lleis cinètiques en les bases de dades del codis geoquímics i de transport reactitu permeten fer prediccions molt més realistes. L’impacte mediambiental causat per l’arsènic alliberat a les aigües depèn de la seva atenuació natural. El principal procés que controla el destí i la mobilitat de l’arsènic aquós és l’adsorció de l’arsenat en fases de ferro precipitades. Per tant, cal tenir en compte el paper que juga l’estat d’oxidació de l’arsènic. En la segona part de la tesi, shan estudiat tant l’oxidació de l’arsènic com l’adsorció de l’arsènic. L’oxidació s’estudia en condicions abiòtiques i biòtiques a pH i composició típics d’aigües àcides de mina, fent servir experiments de tipus batch. S’hi mostra com en condicions biòtiques tenen lloc simultàniament l’oxidació de Fe(II) a Fe (III) i d’arsenit a arsenat, de manera que mentre els bacteris governen la primera, el contingut de Fe(III) domina la segona. En condicions abiòtiques, l’oxidació d’arsenit a arsenat en presència de Fe(III) és lenta, tot i que augmenta augmentant la presència de Fe(III) i de clorur amb llum de dia. L’adsorció d’arsènic en llocs d’AMD, i per tant l’atenuació d’arsènic, ocorre mitjançant l’adsorció d’arsenat en precipitats formats per oxi-hidròxids i oxi-hidròxid-sulfats de ferro (principalment schwertmannita (Fe8O8(OH)5.5(SO4)1.25), K-jarosita (KFe3(SO4)2(OH)6) i goetita (FeOOH)). S’han estudiat les capacitats d’adsorció de la jarosita i de la goetita i s’han comparat amb la de la schwertmannita. Amb aquest propòsit es van fer experiments de tipus batch a pH molt àcid i amb mostres sintetitzades de K-jarosita i de goetita. Sense la competència d’altres anions, la capacitat de la jarosita per eliminar arsenat és més alta que la de la goetita. També s’ha vist que la força iònica té un escàs efecte en l’adsorció d’ambdós minerals, però que la presència de sulfat, que és l’anió més abundant en aigües àcides de mina, minva llurs capacitas d’adsorció. Cal conèixer bé els mecanismes dominants que controlen el contingut d’arsènic en les aigües, no només en condicions de laboratori, sinó també en les condicions de camp. Per tant, en la tercera part de la tesi s’han estudiat el processos d’atenuació de l’arsènic en un sistema natural. Amb aquest objetiu s’han caracterizat exhaustivament l’aigua i els sediments del rieron provinent de la mina abandonada Tinto Santa Rosa, situada a la Faixa Pirítica Ibèrica (IPB). La característica dominant de l’aigua del rierol és un descens del pH aigües avall que va acompanyat d’un decreixement sistemàtic de les concentracions de ferro ferrós i de ferro total, d’arsenit i d’arsenat, així com d’arsènic total. A més a més, els sediments de llit mostren contiguts alts d’arsènic. Els principals mecanismes que dominen el destí i la mobilitat de l’arsènic en aquestes aigües de camp són l’oxidació del ferro i de l’arsènic i la precipitatió de compostos de Fe(III) que adsorbeixen l’arsenat. S’ha proposat un model unidimensional de trasnport reactiu, utilitzant el codi PHREEQC, per explicar i quantificar els processos mencionats que han estat estudiats en condicions de laboratori. / Acid mine drainage (AMD) generated by sulfide oxidative dissolution is a major cause of water contamination world-wide. Arsenic is one of the main AMD pollutants whose concentration can reach up to hundreds of mg L-1, i.e. 5-6 orders of magnitude higher than the limit of 10 μg L-1 for potable water established by the European Union in 1998. This thesis is concerned with the impact of arsenic mobilization along AMD discharges. Oxidation of As-bearing sulfides such as arsenopyrite (AsFeS), As-rich pyrite (FeS2) or marcasite (FeS2) is one of the main sources of arsenic release. The first part of this thesis is focused on the dissolution kinetics of arsenopyrite and marcasite at acidic to neutral pH using long term flow-through experiments. The effects of pH, dissolved oxygen and temperature on their dissolution were assessed. The respective dissolution rate laws were proposed on the basis of the steady-state rates, taking into consideration the slight pH effect and the strong dissolved oxygen effect on dissolution. The incorporation of these rate laws into the kinetic databases of geochemical and reactive transport codes allows us to obtain better realistic simulations. The environmental impact of released arsenic into waters depends on its natural attenuation. The arsenic oxidation state is considered given that the main process that controls the fate and mobility of aqueous arsenic is arsenate sorption onto precipitated Fe-phases. The second part of the thesis discusses arsenic oxidation and arsenic sorption. Oxidation was studied by means of batch experiments under abiotic and biotic conditions at typical AMD water pH and water composition. Simultaneous oxidation of Fe(II) to Fe(III) and arsenite to arsenate occurs under biotic conditions, the former mediated by bacteria, and the latter by the presence of Fe(III). Under abiotic conditions, oxidation of arsenite to arsenate in the presence of Fe(III) is slow, but is enhanced by increasing dissolved Fe(III) and chloride concentrations in the presence of light. Arsenic sorption at AMD sites, and hence arsenic attenuation, occurs via arsenate sorption on new iron-oxyhydroxide and iron-oxyhydroxide-sulphate precipitates (mainly, schwertmannite (Fe8O8(OH)5.5(SO4)1.25), jarosite (KFe3(SO4)2(OH)6) and goethite (FeOOH)). The sorption capacity of goethite and jarosite was studied and compared with the one reported for schwertmannite. To this end, batch experiments were conducted using synthetic powders of K-jarosite and goethite at highly acidic pH. In the absence of competitive effects of other anions, K-jarosite presented better removal efficiency for arsenate, and ionic strength and pH had little effect on the sorption capacity of the two minerals. In contrast, these sorption capacities diminished considerably in the presence of sulfate, which is the main anion in AMD waters. A deeper understanding of the dominant mechanisms controlling arsenic content in waters demands the study of the processes not only under laboratory but also under natural conditions. Accordingly, the third part of this thesis deals with the arsenic attenuation processes in a natural system. To this end, the acidic water and sediments of the abandoned Tinto Santa Rosa mine discharge, located in the Iberian Pyritic Belt, were studied. The most striking feature of the water was a pH decrease accompanied by a systematic decrease in ferrous iron, total iron, arsenite, arsenate and total arsenic concentration. Additionally, bed-stream sediments showed high arsenic contents. The main processes that control the fate and mobility of arsenic in waters in the field were iron and arsenic oxidation, precipitation of Fe(III)- minerals and sorption of As(V) onto them. A 1-D reactive transport model using the PHREEQC code was used to explain and quantify the aforementioned processes that had been studied previously under laboratory conditions.

Many industrial activities discharge sulphate- and metal-containing wastewaters, including the manufacture of pulp and paper, mining and mineral processing, and petrochemical industries. Acid mine drainage (AMD) is an example of such sulphate- and metal-containing waste streams. Formation of AMD is generally the result of uncontrolled oxidation of the sulphide minerals present in the terrain in which the drainage flows with concomitant leaching of the metals. Acid mine drainage (AMD) and other sulphate- and metal-containing waste streams are amenable to active biological treatment. Anaerobic reduction of sulphate, reaction of produced sulphide with metal ions present in the waste stream, and biooxidation of excess sulphide are three main sub-processes involved in the active biotreatment of AMD. Anaerobic reduction of sulphate can be achieved in continuous stirred tank bioreactors with freely suspended cells or in immobilized cell bioreactors. The application of freely suspended cells in a continuous system dictates a high residence time to prevent cell wash-out, unless a biomass recycle stream is used. In an immobilized cell system biomass residence time becomes uncoupled from the hydraulic residence time, thus operation of bioreactor at shorter residence times becomes possible. In the present work, kinetics of anaerobic sulphate reduction was studied in continuous immobilized cell packed-bed bioreactors. Effects of carrier matrix, concentration of sulphate in the feed and sulphate volumetric loading rate on the performance of the bioreactor were investigated. The bioreactor performance, in terms of sulphate reduction rate, was dependent on the nature of the carrier matrix, specifically the total surface area which was provided by the matrix for the establishment of biofilm. Among the three tested carrier matrices, sand displayed the superior performance and the maximum volumetric reduction rate of 1.7 g/L-h was achieved at the shortest residence time of 0.5 h. This volumetric reduction rate was 40 and 8 folds faster than the volumetric reduction rates obtained with glass beads (0.04 g/L-h; residence time: 28.6 h) and foam BSP (0.2 g/L-h; residence time: 5.3 h), respectively. Further kinetic studies with sand as a carrier matrix indicated that the extent of volumetric reduction rate was dependent on the feed sulphate concentration and volumetric loading rate. At a constant feed sulphate concentration, increases in volumetric loading rate caused the volumetric reduction rate to pass through a maximum, while increases in feed sulphate concentrations from 1.0 g/L to 5.0 g/L led to lower volumetric reduction rates. The maximum volumetric reduction rates achieved in the bioreactors fed with initial sulphate concentration of 1.0, 2.5 and 5.0 g/L were 1.71, 0.82 and 0.68 g/L-h, respectively. The coupling of lactate utilization to sulphate reduction was observed in all experimental runs and the rates calculated based on the experimental data were in close agreement with calculated theoretical rates, using the stoichiometry of the reactions involved. The maximum volumetric reduction rates achieved in the immobilized cell bioreactors were significantly faster than those reported for freely suspended cells employed in the stirred tank bioreactors.

Semi-arid regions, like the Okanagan Basin of British Columbia, Canada, are often faced with the difficulty of managing limited groundwater and surface water resources while accommodating rapid population growth and increasing land development. In the South Okanagan Basin, a better understanding of groundwater recharge sources, groundwater availability and susceptibility of water supplies to anthropogenic contamination is needed to best direct and protect the regions water resources. The purpose of this study was: (1) to characterize the regional hydrogeological setting of the South Okanagan Basin by establishing an isotopic and geochemical framework that included precipitation and surface waters of the Okanagan Basin and groundwaters of the South Okanagan Basin; and (2) to characterize nitrate contamination and its sources in shallow groundwaters of the Osoyoos area. Stable isotopes of water, nitrate and dissolved oxygen, groundwater chemistry, water levels and enriched tritium, tritium/helium and/or radiocarbon age dating techniques were used. Two provisional local meteoric water lines were established for the Okanagan Basin: &delta2H=6.06&delta18O31.21 (Osoyoos) and &delta2H=7.03&delta18O-12.68 (West Kelowna). Surface waters of the Okanagan River system were sources of irrigation water in the South Okanagan Basin valley and irrigation-return flow was the primary source of recharge for shallow groundwaters. Fractured bedrock in highlands east and west of the valley were not a significant source of recharge for shallow valley groundwater, however, may recharge deeper, or basal, valley deposits. As irrigation-return flow controls shallow groundwater dynamics in the valley sediments, groundwater quality is susceptible to anthropogenic contamination. In Osoyoos, nitrate was present in shallow groundwaters at concentrations of up to 24.4 mg/l N as a result of fertilizer nitrogen applied at the soil surface, mostly at orchards. Two agricultural drainage systems in north Osoyoos discharge roughly 1,900 kg N/year from nitrate-contaminated groundwater directly into Osoyoos Lake and may contribute in part to its eutrophication.

A drainage basins runoff response can be determined by the connectivity of generated runoff to the stream network and the connectivity of the downstream stream network. The connectivity of a drainage basin modulates its ability to produce streamflow and respond to precipitation events and is a function of the complex and variable storage capacities along the drainage network. An improved means to measure and account for the dynamics of hydrological connectivity at the basin scale is needed to improve prediction of basin scale streamflow. The overall goal of this thesis is to improve the understanding of hydrological connectivity at the basin scale by measuring hydrological connectivity at the Baker Creek Research Basin during 2009. To this end, the objectives are to 1) investigate the dynamics of hydrological connectivity during a typical water year, 2) define the relationship between the contributing stream network and contributing area, 3) investigate how hydrological connectivity influences streamflow, and 4) define how hydrological connectivity influences runoff response to rainfall events. At a 150 km2 subarctic Precambrian Shield catchment where the poorly-drained heterogeneous mosaic of lakes, exposed bedrock, and soil filled areas creates variable contributing areas, hydrological connectivity was measured between April and September 2009 in 10 sub-basins with a particular focus on three representative sub-basins. The three sub-basins, although of similar relative size, vary considerably in the dominant typology and topology of their constituent elements. At a 10 m spatial resolution, saturated areas were mapped using both multispectral satellite imagery and in situ measurements of storage according to land cover. To measure basin scale hydrological connectivity, the drainage network was treated as a graph network with stream reaches being the edges that connect sub-catchment nodes. The overall hydrological connectivity of the stream network was described as the ratio of actively flowing relative to potentially flowing stream reaches, and the hydrological connectivity of the stream network to the outlet was described as the ratio of actively flowing stream reaches that were connected to the outlet relative to the potentially flowing stream reaches. Hydrological connectivity was highest during the spring freshet but the stream network began to disintegrate with its passing. In some drainage basins, large gate keepers were able to maintain connectivity of the stream network downstream during dry periods. The length of the longest stream was found to be proportional to contributing area raised to a power of 0.605, similar to that noted in Hacks Law and modified Hacks Law relationships. The length of the contributing stream network was also found to be proportional to contributing area raised to a power of 0.851. In general, higher daily average streamflows were noted for higher states of connectivity to the outlet although preliminary investigations allude to the existence of hysteresis in these relationships. Elevated levels of hydrological connectivity were also found to yield higher basin runoff ratios but the shape of the characteristic curve for each basin was heavily influenced by key traits of its land cover heterogeneity. The implications of these findings are that accurate prediction of streamflow and runoff response in a heterogeneous drainage basin with dynamic connectivity will require both an account of the presence or absence of connections but also a differentiation of connection type and an incorporation of aspects of local function that control the flow through connections themselves. The improved understanding of causal factors for the variable streamflow response to runoff generation in this environment will serve as a first step towards developing improved streamflow prediction methods in formerly glaciated landscapes, especially in small ungauged basins.

The increasing global air temperature will trigger changes in the global mean water vapor, precipitation patterns and evapotranspiration, which further leads to changes, for instance, instream flow, groundwater flow and soil moisture. Projections of future changes in thehydrological regime of the Aral Sea Drainage Basin (ASDB) in Central Asia are however highlyuncertain, due to complexities of natural and engineered water systems of the basin. The AmuDarya River Delta (ADRD) is vital to the water budget of the Large Aral Sea, the livelihood inUzbekistan and Turkmenistan, as well as the surrounding riparian ecosystem. This study attemptsto investigate responses of river flow in the Aral Sea Drainage Basin and key riparian vegetationspecies (of the so-called Tugai community) in the Amu Darya River Delta to projected futureclimate change. Results from hydrological model and outputs from multi-GCM predictions providea basis for conducting more robust quantitative analysis of possible future hydro-climatic changesin the Amu Darya River Basin. A qualitative synthesis of the suitability of Tugai is furthermoreperformed in order to increase the knowledge of the riparian vegetation status under thechanging hydro-climatic conditions. The results show that the averaged temperature in the ASDBis likely to continuously increase and yield a total increase of about 2 °C ~ 5°C by 2100. Thechange trend of the annual regional precipitation of 2100 is relatively unclear, with estimatesranging from 50 mm lower than today to 75 mm higher than today. Modeled ensemble means (EM)river flow, obtained from hydrological modeling of climate output from multi-GCM projections,converge on showing future decreases in river runoff (R). Projected absolute R may decrease tozero around 2100, implying no surface flow and a dry out near the river outlet. The relationship ofwater flux between upstream and downstream will be changed dramatically due to climatechange. More specifically, R of the upstream region will decrease, and it is likely to becomeinsufficient for feeding downstream river reaches as it used to. The decreased river flow in thedelta may accelerate the desertification and salinization processes. Consequently, speciestransitions may occur, along with degradations of the existing Tugai communities. Theuncertainties of hydro-climatic change projections to some extent hinder the understanding of thedynamic hydrological-climatic-ecological system. However, the detailed responses of the delta toclimate change based on multiple qualitative and quantitative analyses provide an important basisfor the formulation of more robust forecasts on the future ecological development in the ADRD, and further for recommendations of measures to mitigate the ecosystem’s deterioration under achanging climate.