Groundwater flow typically provides stable stream habitat within glacierised floodplains. However, spatio-temporal differences within and between groundwater flow pathways can create marked variability in the physicochemical characteristics of groundwater-fed streams. Research conducted on a floodplain terrace of the Toklat River, Denali National Park, Alaska, predominantly from May to September 2008, determined the influence of groundwater flow dynamics upon benthic and hyporheic macroinvertebrate assemblages. During periods of resource depletion benthic macroinvertebrate abundance was dependent upon contributions from specific flow pathways (DFSdeep), which supplied fine particulate organic matter. Dynamics of groundwater flow pathways influenced macroinvertebrates throughout the summer, however, with higher diversity observed in perennial streams which received groundwater flow from DFSdeep. Ephemeral flow pathways of glacial seepage supported lower diversity. Within the hyporheic zone, environmental stability of surface waters was influential, as this reflected the sub-surface residence time of percolating waters; nested routes of flow within each flow pathway, of varying length or permeability, created differences in the environmental stability of each stream. Macroinvertebrate diversity in the hyporheic zone was higher at sites of lower surface environmental stability, suggesting possible migration into the hyporheic zone. Digital remote sensing used to estimate the spatial extent of groundwater upwellings within two national parks in Alaska indicated that these groundwater-fed habitats are widespread.

The impact of a 1 in 40 year flood on the morphology and sedimentology of the sandy braided South Saskatchewan River, Canada was assessed. Comparison of 2004 - 2007 repeat GPR surveys and the production of DEMs of difference allowed quantification of the initial and long-term 2005 flood impact on reach morphology and sedimentology. Main results show that even though a significant initial morphological impact was caused due to the flood through net erosion and channel incision across Bar A, subsequent low-magnitude high-frequency floods were able to rework morphology due to the ability to transport the medium sized sand bed load. In the subsurface, no distinct flood signature has been left, as flood deposits are similar to the scale and composition of deposits produced by low-magnitude high-frequency floods. Consequently, little evidence of such a flood event will be preserved in the sedimentary record. The research has also highlighted some important findings with respect to linking morphological processes to sedimentary deposits. In particular they have suggested the revision of depositional models for braided rivers, and further research on the relationship between bedform geometry and flow depth in natural rivers. The results have wider applications to other sand bed braided rivers and may aid interpretation and modelling of such deposits on a wider scale.

A methodology of assessment is presented of the groundwater resources available in fracture zones, within the weathered mantle of gneiss, migmatite and granite. A model of weathering is developed, and values of porosity, hydraulic conductivity and electrical resistivity assigned to the different grades of weathering. A geophysical technique is developed, based upon a combination of electrical resistivity profiling and sounding, which allows a volume estimate of the various weathering grades to be made. A finite difference algorithm is used for this estimate which enables the apparent resistivity response of an inhomogeneous resistivity distribution to be calculated. An iterative approach is then adopted, adjusting the resistivity model until the calculated response agrees with the field data. An analysis of recharge in a savanna climate is developed based upon the Monteith equation for predicting evapotranspiration, and upon a model of unsaturated zone soil moisture movement. The recharge function developed is included in a one dimensional catchment water balance model. The results from this model are compared with observed runoff and groundwater hydrographs. The estimate of recharge is combined with the estimate of aquifer storage to produce an assessment of available groundwater. Optimal methods for the development of the resource are discussed. While developed in Northern Nigeria, the methodology of assessment is applicable to any similar geological and climatological environment.

The North Sakhalin Basin is a polyphase Neogene basin situated on an active strike-slip plate boundary between the Amur and Okhotsk microplates.  This basin contains a sedimentary record of the Amur River, as well as the tectonic processes which have resulted in the formation and deformation of the basin.  I use a multi-disciplinary approach, involving heavy mineral analysis, seismic interpretation and geomorphic observations and analyses, to constrain the evolution of the landscape, sedimentary basins and fluvial systems at this active continental margin. Detrital mineralogy and integrated sediment accumulation rates indicate that the drainage basin of the Amur River has been relatively stable since the Early Miocene, with no evidence for continental-scale drainage capture during this time.  Instead, sediment delivery to the basin has responded to a number of tectonic and climatic processes, most notably the onset of Northern Hemisphere glaciation in the Pliocene and uplift and erosion of the North Sakhalin Basin in the Late Neogene.  By contrast, the Colorado River, which also has a delta on an active strike-slip margin, has been profoundly affected by tectonic processes at the continental margin, resulting in major drainage re-organisation in the Late Neogene. Sediment delivery to the North Sakhalin Basin has been strongly affected by tectonic processes along the Sakhalin-Hokkaido Shear Zone.  The basin underwent a phase of transtension during the Early Miocene (>15 Ma), followed by continued strike-slip offset during the Middle-Late Miocene (15-6.3 Ma), and finally transpression during the Pliocene which is still ongoing today.  The diachronous, northeastward-propagating deformation and uplift of the North Sakhalin Basin (initiated between 6.3-3.6 Ma) is preserved in the geomorphic characteristics of fluvial networks, the first-appearance of recycled deltaic sediments and by onlapping reflector terminations on offshore anticlines.  The landscape of Sakhalin is transient, and continuing to deform in the present day.

Στα πλαίσια της παρούσας πτυχιακής εργασίας μελετώνται οι υδρογεωλογικές και υδροχημικές συνθήκες που επικρατούν στις καρστικές πηγές της Οκτωνιάς στην Κεντρική Εύβοια. Η περιοχή ανήκει στην Πελαγονική Γεωτεκτονική Ζώνη και αποτελείται από ασβεστόλιθους του Ιουρασικού και Τριαδικού, Αλλουβιακές αποθέσεις και νεογενελις σχηματισμούς. Για ττην υδροχημική έρευνα χρησιμοποιήθηκαν δείγματα από 6 πηγές. Με βάση τα αποτελέσματα των αναλύσεων και με την βοήθεια των διαγραμμάτων Piper τα νερά κατατάσσονται στην ομάδα των γαιοαλκαλικών- οξυανθρακικών νερών. / In the frame of the present undergraduated thesis the hydrogeological and hydrochemical conditions that prevail in the karst springs of Oktonia region in Central Evia are studied. The study area belongs to Pelagonian Geotectonic zone and is constituted of Jurassic and Triassic limestones, Alluvial deposits and Neogene formations. Samples of 6 water springsare collected and analyzed in the laboratory of Hydrogeology in the Department of Geology,University Patras. The waters are classified as geo- alkaline with elevated alkaline percentage. The springs present very low discharge rates.

Σκοπός της παρούσας πτυχιακής εργασίας είναι η προσέγγιση και μελέτη των υδρογεωλογικών συνθηκών τμήματος της λιγνιτοφόρου λεκάνης Αναργύρων – Αμυνταίου στην Πτολεμαΐδα. Η περιοχή μελέτης έχει οικονομική σημασία για τις γύρω περιοχές καθώς μεγάλο μέρος του πληθυσμού εργάζεται στα ορυχεία Πτολεμαΐδας. Στα πλαίσια της παρούσας εργασίας πραγματοποιήθηκαν μετρήσεις στάθμης σε γεωτρήσεις της περιοχής, δειγματοληψία και υδροχημικές αναλύσεις καθώς επίσης και χρήση προγραμμάτων πληροφορικής και τηλεπισκόπισης για την κατασκευή αναλυτικών χαρτών και διαγραμμάτων για την ανάλυση των υδρογεωλογικών συνθηκών. Επιπλέον, συγκεντρώθηκαν δεδομένα και υπάρχουσες μελέτες που αφορούν γεωλογικά και τεκτονικά στοιχεία της ευρύτερης περιοχής όπως επίσης και κλιματολογικά δεδομένα. / --

Σκοπός της παρούσας εργασίας είναι η μελέτη της υδρογεωλογικής και υδροχημικής κατάστασης της κοιλάδας του Αστακού. Η περιοχή μελέτης βρίσκεται στην Δυτική Ελλάδα στο νομό Αιτωλοακαρνανίας. Ανήκει στην Ιόνια ζώνη, και καλύπτεται κατά κύριο λόγο από την μετα-Τριαδική ανθρακική ακολουθία, η οποία αποτελείται από τους Ασβεστόλιθους Παντοκράτορα, Ανώτερου Λιάσιου, Βίγλας, Σενωνίου και Παλαιόκαινου. Το ανάγλυφο της περιοχής είναι έντονο, με μεγάλα υψόμετρα. Έχει υποστεί έντονη τεκτονική καταπόνηση η οποία παίζει καθοριστικό ρόλο στη διαμόρφωση του υδροχημικού χαρακτήρα της περιοχής. Στην περιοχή αναπτύσσονται καρστικοί υδροφόροι στους ασβεστόλιθους Παντοκράτορα αλλά και ελεύθερος υδροφόρος στις αλλουβιακές αποθέσεις της κοιλάδας του Αστακού. Στα πλαίσια της παρούσας εργασίας έγιναν δύο εκτεταμένες δειγματοληψίες κατά την ξηρή και υγρή περίοδο, καθώς και συλλογή δειγμάτων νερού και μετρήσεων παροχής σε επιλεγμένες γεωτρήσεις και πηγάδια σε μηναία βάση. Προσδιορίστηκαν οι κύριοι υδροχημικοί τύποι των νερών, Ca-Mg-HCO3 και Ca-HCO3. Παρατηρήθηκε επίσης υφαλμύρινση πηγής, η οποία εμφανίζεται στην επαφή ασβεστολίθων Ηωκαίνου με τις αλλουβιακές αποθέσεις και αποστραγγίζει το ανατολικό τμήμα της περιοχής, καθώς και σε υδροσημεία κατά μήκος αυτής της επαφής σε απόσταση έως 1,8 km από την θάλασσα. Ο υδροχημικός χαρακτήρας των νερών της περιοχής μελέτης επηρεάζεται από τη διάλυση των Τριαδικών ανθρακικών λατυποπαγών, της γειτονικής περιοχής. Τέλος από τα υδρογράμματα και τους συντελεστές στείρευσης που υπολογίστηκαν προέκυψε ότι η ροή του νερού γίνεται μέσω καρστικών αγωγών. / The subject of the present diploma thesis is the hydrogeological study of the basin of Astakos area from drilling and sampling wells.

Large wood and its accumulations are poorly understood despite being an important feature in the functioning of forested river channels and floodplains. Large wood has previously been removed from rivers in order to reduce flow resistance and increase channel conveyance. However, recently there has been an appreciation of the role of large wood accumulations in creating important aquatic habitat, increasing geomorphic diversity, re-connecting river channels to their floodplains and in the development of multi-channel anastomosed river patterns. This thesis examines the role that large wood plays at a range of scales in a low-order forested stream in the New Forest, Southern England. The study river was subject to restoration measures, involving the addition of large wood to the river channel, as part of an EU LIFE III project. An empirical and Froude-scaled flume approach is taken to determine the role of large wood accumulations upon the reach-scale flow resistance values. Large wood accumulations from a variety of environments are assessed to determine the hydraulic effects of accumulations of different architecture in different environments. Field data from the study catchment is used to show the role of large wood in increasing the frequency and duration of reach-scale, floodplain inundation. Hydrological data shows the impact the restoration has upon both flood peak magnitude and flood peak travel time highlighting the potential benefits of large wood to downstream flood risk. A 2-Dimensional model is produced which simulates the effect of a range of large wood accumulations upon the inundation extent. An approach using spatial diversity metrics, widely used in ecological sciences, is conducted in an attempt to quantify the flow depth and flow velocity diversity, which can influence flow habitat diversity. Results show that large wood can initiate an anastomosing flow pattern which allows increases flow depth diversity by up to 49% and flow velocity diversity by up to 48%

The afforestation of upland areas in the UK has been the largest rural land use change this century. As a consequence of afforestation the bed load yields of upland catchments have been shown to increase substantially. The upland catchment bed load is transported downstream, through the transfer zone to the lowland reaches where it may enter storage in barforms, cause flow diversion and cause channel instability. This study investigates the Afon Trannon, a river in mid-Wales whose upland catchment was afforested between 1948 and 1978 and whose lowland channel is currently unstable. Historical rates of channel change in the lowland channel have been quantified using aerial photogrammetry in ERDAS Imagine GIS. Channel instability is shown to increase significantly between 1963 and 1976, some 15 years after upland catchment afforestation. However, upland catchment bed load yields are shown to be of low magnitude (up to an estimated maximum of6.35 t km-2 yr") and incapable of producing the high medium-term lowland channel change rates observed (up to 1.88 m yr" between 1963 and 1976). Contemporary channel DTMs constructed from field survey data have allowed the construction of a contemporary lowland channel sediment budget. Local inputs of bed load from composite bank erosion are shown to dominate in the budget and reaches of maximum instability are shown to correspond with the location of these composite banks. Additionally. flood magnitude and frequency are shown to have increased since 1988 from a maximum stage of 1.50 m between 1969 and 1988 to a maximum stage of2.23 m between 1989 and 2000. A conceptual model is presented in which the medium-term instability of the lowland Afon Trannon is suggested to be triggered by local lowland bed aggradation as a result of elevated upland catchment bed load yields and a risk assessment diagram provides advice to river engineers and fluvial geomorphologists interested in assessing the potential stability of lowland rivers whose upland catchments have been afforested.

The climate of the Wester Ross region of NW Scotland is particularly sensitive to fluctuations in the strength and latitude of the North Atlantic Gulf Stream. This was particularly apparent during the last deglaciation (14.7-12.9 ka), when overall climatic amelioration was interrupted by periods of cooling, the most significant being a 1.2 ka return to glacial conditions during the Younger Dryas (12.9-11.5 ka). Glacial readvances during these cooling episodes left behind numerous geomorphological features, which have been mapped and interpreted through a variety of methods, including fieldwork observations, aerial photography and digital elevation models, to form a detailed reconstruction of the style and timing of deglaciation. These methods were augmented by the study of 3D digital models, produced by combining 5cm resolution, Light Detection and Ranging (LiDAR) scans with colour photography, leading to the production of a detailed geomorphological map of a cirque formation in Torridon, Wester Ross, which was covered by an ice-sheet at the Last Glacial Maximum, and experienced localised ice flow during subsequent deglaciation and readvances. Six statistically comparable cosmogenic 10Be bedrock exposure ages give a Younger Dryas age for sites in Torridon and Applecross (Wester Ross), and have also been used to constrain the vertical extent of these ice fields. Reconstructions of these ice bodies revealed that the Torridon ice field (mean ELA, 482m) covered ~100km2, over twice the surface area covered by the Applecross ice field (~43km2). This could have resulted from the survival of ice in Torridon prior to the onset of the Younger Dryas cooling, and is tentativelty supported by pre-Younger Dryas cosmogenic 10Be exposure ages from this study and previous studies, which imply that ice existed close to the Wester Ross coastline and within central Torridon between 14-13ka. The Applecross ice field mean ELA (361m) was lowered by the presence of independent glaciers, which formed in low-lying troughs as snow was efficiently transferred to the NE by prevailing SW winds. Using empirical values from a global dataset, average annual Younger Dryas palaeoprecipitation values for the Torridon and Applecross ELAs are 2010 ± 266 and 2312 ± 534 mm a-1 respectively, suggesting a wetter climate than today. Palaeoprecipitation calculated using equations based on a climate model of NW Scotland, yield lower values between 1005 ± 67 mm a-1 and 1758 ± 118 mm a-1 for the Torridon ELA and 1205 ± 233 mm a-1 to 2109 ± 407 mm a-1 for the Applecross ELA, perhaps a more reliable estimate which reflect enhanced continentaility, promoted by the formation of sea ice on the NE Atlantic seaboard during the Younger Dryas.Despite the rapid warming observed in palaeotemperature proxies, studies of glacial geomorphology and basal shear stress suggest that initial deglaciation was slow, oscillatory and warm-based, leading to the formation of prominent retreat moraines in the lower valleys. This prolonged transition can be related to the northward migration of sea ice and the gradual reintroduction of a Gulf Stream-dominated maritime climate. Ice remaining in the central area down-wasted in-situ as the regional ELA increased, creating hummocky landscape. Finally, cosmogenic 10Be exposure ages indicate that glaciers (probably characerised by a polythermal regime) retreated into the high north-facing corries at approximately 11.8ka, depositing a series of flutes.