Thesis (Ph.D.(Civil Engineering))--University of Pretoria, 2001. / Summaries in Afrikaans and English. Includes bibliographical references.

Includes bibliographical references (p. 250-262).

Thesis (M.A.)--University of Wyoming, 2009. / Title from PDF title page (viewed on July 23, 2010). Includes bibliographical references (p. 124-131).

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 82-87). Also available on the World Wide Web.

Το απόθεμα του Ευρωπαϊκού χελιού (Anguilla anguilla), βρίσκεται σε ιστορικό ελάχιστο και η αλιεία του δεν είναι βιώσιμη, με τα δεδομένα να δείχνουν μείωση της στρατολόγησης της τάξης του 95%. Παρόμοιες πτωτικές τάσεις ισχύουν και στην Ελλάδα. Γι’ το λόγο αυτό ο κανονισμός της Ευρωπαϊκής Ένωσης 1100/2007 αναγκάζει όλα τα κράτη μέλη να προχωρήσουν στη σύνταξη διαχειριστικών σχεδίων για το χέλι προκειμένου να αυξηθούν οι διαφυγές αργυρόχελου στο 40% των διαφυγών που θα είχαμε αν δεν υπήρχαν οι ανθρωπογενείς παρεμβάσεις. Οι λόγοι μείωσης του αποθέματος του Anguilla anguilla είναι διάφοροι, με πιο σημαντικό για την παρούσα εργασία τις τεχνητές δομές που αποκλείουν κατάλληλους βιοτόπους για το χέλι. Στην παρούσα εργασία έγινε μια πρώτη τυπολογία των φραγμάτων, με ιδιαίτερη έμφαση στα φράγματα των Διαχειριστικών μονάδων 1 και 2 για το χέλι. Για το σκοπό αυτό, δημιουργήθηκε μια βάση δεδομένων, με στοιχεία από την Ελληνική Επιτροπή Μεγάλων Φραγμάτων και έρευνα στο google earth. Καταρχάς, τα αποτελέσματα της πρώτης τυπολογίας, έδειξαν ότι φράγματα σε ποσοστό 80% έχουν ύψος 0-50 m και από αυτά το 35% έχει ύψος 10-20m και το 25% 20-30m. Το 40% των μεγάλων φραγμάτων βρίσκεται σε απόσταση από τη θάλασσα έως 20km. Τα φράγματα που βρίσκονται πιο κοντά στην ακτή είναι τα Πουρνάρι ΙΙ (27km), Πουρνάρι Ι (30km), ο Λούρος (42km), το φράγμα του Φλόκα (17km), ο Στράτος (70km) και το φράγμα Αχυρών (11km). Το 35% των φραγμάτων χρησιμοποιείται αποκλειστικά για άρδευση και 10% αποκλειστικά για ύδρευση. Το 50% των φραγμάτων βρίσκεται σε υψόμετρο 0-200m και το 45% των φραγμάτων βρίσκεται σε υψόμετρο 200-900m. Η τυπολογία των φραγμάτων βάσει του όγκου του ταμιευτήρα έδειξε ότι τα περισσότερα φράγματα (60%) έχουν όγκο ταμιευτήρα έως 1.000.000m3 και ποσοστό 20% από 1.000.000 m3 έως 5.000.000m3. Στη συνέχεια, αξιολογήθηκαν τα παραπάνω φράγματα για την επίδραση τους τόσο στην ανάδρομη, όσο και στην κατάδρομη μετανάστευση. Ως προς την ανάδρομη μετανάστευση των χελιών, σύμφωνα με τα κριτήρια του Steinbach και με βάση τη σειρά του εμποδίου στην πορεία του χελιού, σημαντικά κρίθηκαν τα φράγματα του Στράτου, Πουρναρίου ΙΙ, Φλόκα, Μόρνου και Εύηνου. Ως προς την κατάδρομη μετανάστευση, σημαντικά κρίθηκαν τα φράγματα Καστράκι, Στράτος, Πουρνάρι Ι και ΙΙ, Λάδωνα, Φλόκα, Λούρου, καθώς είναι φράγματα που χρησιμοποιούνται -είτε αποκλειστικά είτε σε συνδυασμό με άλλες χρήσεις- για παραγωγή υδροηλεκτρικής ενέργειας. Παρ’ όλα αυτά, τα παραπάνω συμπεράσματα δεν είναι απόλυτα, καθώς πρέπει να αξιολογηθεί η αφθονία του χελιού στη συνολική μεταναστευτική του οδό. Στη Ευρώπη χρησιμοποιούνται τεχνικές παρεμβάσεις για τη διευκόλυνση της μετανάστευσης, όπως σκάλες χελιών ή διακοπή της λειτουργίας των τουρμπινών των υδροηλεκτρικών εργοστασίων. Στην Ελλάδα μεγάλο ποσοστό φράγματων έχουν μεγάλο ύψος (πάνω από 10m), όταν στην Ευρώπη ύψος πάνω από 2m θεωρείται σχεδόν απροσπέλαστο από τα χέλια, σύμφωνα με τα κριτήρια του Steibach. Τεχνικές λύσεις, όπως δημιουργία ειδικών χελιοδιαδρόμων, ίσως να μην ενδείκνυται λόγω αυτής της ιδιομορφίας. / The European eel (Anguilla anguilla) fishery is considered no more sustainable. In fact, present recruitment is about 1-5% of the maximum levels recorded in the past (early 70’s). Similar downward trends are observed in the Hellenic landings. For this reason, the EU regulation 1100/2007 obliges all Member States to propose management plans for the eel. The main objective is to increase silver eel escapement to the sea in order to participate in the reproduction of the population. The escapement should reach 40% of the escapement occurring without anthropogenic influence. The reasons reducing the stock of Anguilla anguilla are various, with the most important in this study, the artificial structures which exclude suitable habitat for eel. In the present a typology of dams was developed, with special emphasis on dams in Eel Management Units 1 and. For this purpose, we created a database with data from the Greek Dams Commission and from geographical elements about the position and altitude of the dams. The results revealed that 80% of the dams have heights varying between 0 and 50 m (35% have 10-20m height and 25% 20-30m). About 40% of large dams are located at less than 20km from the sea. The dams closest to the shore is Pournari II (27km), Pournari I (30km), Louros (42km), Stratos (70km), Floka (17km) and Axyron (11km). 35% of the dams are used for irrigation and only 10% exclusively for water supply. 50% of dams are in altitudes 0-200m and 45% of dams are in altitude 200-900m. The volume of 60% of the reservoirs was up to 1.000.000 m3 and 20% have reservoir volumes up to 5.000.000m3. The dams were evaluated for their effect both on upstream, and downstream eel migration. For the upstream migration of eels, according to the criteria of Steinbach and based on their sequential position from the sea, the major dams were Stratos, Floka, Pournari II, Mornos and Evinos. As for the downstream migration, significantly important dams are Kastraki, Stratos, Floka, Pournari I and II, Ladon, Louros, because these dams are used, either alone or in combination with other uses, for hydro-energy production. Nevertheless, these hierarchy is only based on geographical and technical elements and it have to be completed by the abundance of eel in the related ecosystems.. In Europe technical measures to facilitate the migration of eels comprise fish-laddes or shutting down the turbines of hydroelectric plants. In Greece, a large percentage of the dams have great height (over 10m), when in Europe height over 2m is considered almost impassable by the eel. In these cases, technical solutions, such as creating special eel passes, may be expensive, difficult and of reduced efficiency.

Pakistan currently experiences a deficit in its energy supply and upcoming water shortage. Lack of energy negatively impacts the country's economy, and water shortage would put stress on its agriculture, for example. Furthermore, climate change will further exacerbate these two problems. Dams are considered as a solution because of their ability to manage water resources while generating electricity. Informed by Michel Foucault's power/ knowledge, the purpose of this thesis is to understand how energy and water professionals in Pakistan view sustainable development, and if dams can be considered as sustainable development and climate change adaptive infrastructure. Drawing on interviews in Pakistan, I found that professionals supported dams through mobilizing technocratic discourses that were perceived as apolitical. Yet, I also find that these discourses are political, and I discuss the ramifications of the mobilization of technical discourses that claim to be apolitical for future energy policy decisions in Pakistan.

Master of Arts / Department of Geography / Jida Wang / In the 1950s-60s, the world was experiencing a dramatic increase in artificial water impoundments in an unprecedented effort to eliminate spatial and temporal variations in water accessibility. Dam construction has since decreased, but recently, efforts to supply water and power to a booming world population may once again spark another dam construction boom. Water supplies in some regions are already highly stressed in an effort to satisfy the ever-growing water demand for agriculture, industrial, and domestic uses. With nearly 30% of the world’s population living in water-scarce regions, an improved understanding of total stored surface water has never been more needed. Yet, a complete and spatially-explicit, worldwide inventory of such storage capabilities is lacking. Using several open-source dam registries and high-resolution global lake mapping datasets extracted from thousands of Landsat images, we here aim to provide an updated and spatially-explicit inventory of dams and artificial reservoirs across the world. The following research uses novel techniques to merge 5 authoritative, open-source dam registries into a single dam and reservoir dataset, which we deemed as the Global Dam and Reservoir Inventory (GDRI). In total, GDRI documents 89,500 dams and 83,767 reservoirs for a total capacity of 8,492km3 and total surface area of 754,551km2. Reservoirs account for approximately 2.5% of the Earth’s terrestrial water. In other words, 1 unit of water for every 40 units has been artificially created. Further downscaling of the non-geocoded records provided by the International Commission of Large Dams (ICOLD) using similar geocoding methods allowed for the thorough use of all available ICOLD records. Additional capacity estimates from downscaled ICOLD records increased the GDRI capacity documentation to 8,603km3 and surface area documentation to 859,271km2. Compared to its counterpart, the Global Reservoir and Dam dataset (GRanD), GDRI increased the number of dams documented by 1204%, reservoirs by 1127%, total capacity by 37%, and total surface area by 68%. Initial water impoundment from dam construction activities can lower sea level by permanently trapping water storage on land. Dam construction resulted in an equivalent sea level drop (SLD) of 23.4mm or 0.08mm/yr. Since the dam construction boom of the 1950s-1960s, yearly SLD increased to 0.27mm/yr. By considering the hydrological characteristics of dam location, in terms of endorheic and exorheic basins, we found that exclusion of endorheic located dams decreases the overall effect on SLD by 5.47% or 1.28mm. Failure to consider the hydrologic characteristic of dam location can result in the overestimation of dam-induced SLD. After the dam construction boom of the 1950s-1960s, the world has seen a decreasing trend in dam construction, but developing countries (China, Brazil, India) are still actively pursuing dam projects that are larger and more ambitious than ever before. We see less developed countries often lack the capabilities for dam construction possibly increasing stress on natural water supplies in those regions. The datasets produced are by no means perfect. Overall, the described procedures should be considered a heuristic model, where fastidious quality assurance and automated procedures work to thoroughly eliminate many of the issues encountered with the dataset production, but errors may still exist. However, duplication between the contributing dam datasets, spatial limitations of the lake datasets, imperfect geocoding procedures, and inclusion of more dam datasets provide opportunity for future refinement and improvement of the datasets. This research contributes vital information about anthropogenic water resources that incrementally enhances our knowledge of global hydrology and the interactions taking place between different water entities.

Reservoir spillways are designed to pass extreme flood events without significant damage. For Category A dams in the UK (whereby a breach will endanger lives in a community), designs are based on the Probable Maximum Flood (PMF) arising from the critical duration Probable Maximum Precipitation (PMP). This may occur in the winter, coupled with snowmelt, or in the summer when more heat for convection is available. This thesis details an analysis of 20 extreme rainfall events which occurred in the UK in the past 15 years and were observed by radar. Storm efficiencies have been determined in a Lagrangian frame of reference for these events and used as input into a storm model to determine the corresponding PMP. Results show that while the peak rainfall rates are somewhat less with the storm model than suggested by the NERC FSR (current UK guidelines), the overall volume of rainfall is slightly greater resulting in differences in the maximum storage requirement of the reservoir.

M.Ing. (Civil Engineering) / The dissolved air flotation process can be used for different functions in the drinking waterand sewage treatment fields. The focus for this study was on thickening of activated sludge. At first literature was studied to identify all possible parameters. Then five plants were visited periodically and the physical layout and operating parameters were documented. With the examination of the data the different existing models were evaluated, and new relationships were investigated.

No description available.