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140 σ., Αντικείμενο της παρούσας μεταπτυχιακής εργασίας είναι, αρχικά, η περιγραφή και ανάλυση της βάσης δεδομένων ιστορικών πλημμυρών που ορίζεται από την Οδηγία 2007/60/ΕΚ για τις πλημμύρες και η δημιουργία μιας "ταυτότητας" για τα πλημμυρικά επεισόδια που περιέχονται σε αυτή. Απώτερος στόχος της δημιουργίας της είναι η σύνδεση των τυχόν καταστροφών με το ύψος της βροχόπτωσης που έπεσε στην περιοχή την ημέρα της πλημμύρας. Στο πρώτο κεφάλαιο, γίνεται μια πρώτη εισαγωγή στην συχνότητα εμφάνισης πλημμυρών στην Ελλάδα, αλλά και μια αναφορά στις πλημμύρες που καταγράφονται στην ελληνική μυθολογία. Επίσης, ορίζεται ο σκοπός της εργασίας και τα πρωτότυπα σημεία της. Στο δεύτερο κεφάλαιο, αναλύεται η Οδηγία 2007/60/ΕΚ για τις πλημμύρες, τα στάδια εφαρμογής της, τα βασικά της σημεία και η αναφορά της δημιουργίας βάσης δεδομένων ιστορικών πλημμυρών στην προκαταρκτική αξιολόγηση των κινδύνων πλημμύρας. Στο τρίτο κεφάλαιο, περιγράφεται η χρησιμότητα και η αναγκαιότητα της βάσης δεδομένων ιστορικών πλημμυρών. Γίνεται περιγραφή των πεδίων που συμπληρώνονται για τα πλημμυρικά γεγονότα και της μεθοδολογίας αποθήκευσής τους. Στο τέταρτο κεφάλαιο, αναφέρονται οι πηγές που χρησιμοποιήθηκαν για τη συμπλήρωση των πεδίων της βάσης. Στη συνέχεια περιγράφεται η χωρική και χρονική στατιστική ανάλυση του συνόλου των επεισοδίων που περιλαμβάνονται στη βάση και τα αποτελέσματά της. Στο πέμπτο κεφάλαιο, περιγράφεται η προτεινόμενη "ταυτότητα" για τα πλημμυρικά επεισόδια και δίνονται παραδείγματά της για την κατανόησή τους, καθώς και για την περαιτέρω εισαγωγή πληροφοριών σε αυτές. Ακόμη, γίνεται αναφορά στις πηγές πληροφοριών που χρησιμοποιήθηκαν κατά τη διαδικασία συμπλήρωσης των "ταυτοτήτων" και στα προβλήματα που αντιμετωπίστηκαν. Στο έκτο κεφάλαιο, το οποίο είναι και το τελευταίο, συγκεντρώνονται όλα τα συμπεράσματα, οι παρατηρήσεις και οι διαδικασίες που προέκυψαν κατά τη διάρκεια εκπόνησης της παρούσας μεταπτυχιακής εργασίας. Τέλος, γίνονται προτάσεις για περαιτέρω εξέλιξη της ανάλυσης των πλημμυρικών γεγονότων., The subject of this thesis is, firstly, the description and the analysis of the historical flood database, as it is defined by the Directive 2007/60/EC concerning the floods, and creating an "identity" for the flood episodes contained therein. The ultimate goal of creating this identity is to link the disasters of each flood to the amount of rainfall that fell on the day of the flood. The first chapter is an introduction to the incidence of floods in Greece, but also a reference to the floods recorded in Greek mythology. The purpose of the thesis is defined, as well as the prototype points. The second chapter analyzes the Directive 2007/60/EC, describing its stages of implementation, the key points of the report and the creation of the historical database in the preliminary flood risk assessment. The third chapter describes the utility and necessity of historical flood database. The fields required for the flood events and the storage methodology is described. In the fourth chapter, there is a reference to the sources used to collect information for the database. The spatial and temporal statistical analysis of all episodes included in base and its effects is described. The fifth chapter analyzes the proposed "identity" for flood incidents and examples are given for better understanding. Also, it refers to the sources of the information used in the filling procedure of the "identities" and the problems encountered. In the sixth chapter, which is the last one, all findings, observations and procedures that emerged during preparation of this thesis are collected. Finally, suggestions are made for further development of the analysis of flood events.

140 σ., Αντικείμενο της παρούσας μεταπτυχιακής εργασίας είναι, αρχικά, η περιγραφή και ανάλυση της βάσης δεδομένων ιστορικών πλημμυρών που ορίζεται από την Οδηγία 2007/60/ΕΚ για τις πλημμύρες και η δημιουργία μιας "ταυτότητας" για τα πλημμυρικά επεισόδια που περιέχονται σε αυτή. Απώτερος στόχος της δημιουργίας της είναι η σύνδεση των τυχόν καταστροφών με το ύψος της βροχόπτωσης που έπεσε στην περιοχή την ημέρα της πλημμύρας. Στο πρώτο κεφάλαιο, γίνεται μια πρώτη εισαγωγή στην συχνότητα εμφάνισης πλημμυρών στην Ελλάδα, αλλά και μια αναφορά στις πλημμύρες που καταγράφονται στην ελληνική μυθολογία. Επίσης, ορίζεται ο σκοπός της εργασίας και τα πρωτότυπα σημεία της. Στο δεύτερο κεφάλαιο, αναλύεται η Οδηγία 2007/60/ΕΚ για τις πλημμύρες, τα στάδια εφαρμογής της, τα βασικά της σημεία και η αναφορά της δημιουργίας βάσης δεδομένων ιστορικών πλημμυρών στην προκαταρκτική αξιολόγηση των κινδύνων πλημμύρας. Στο τρίτο κεφάλαιο, περιγράφεται η χρησιμότητα και η αναγκαιότητα της βάσης δεδομένων ιστορικών πλημμυρών. Γίνεται περιγραφή των πεδίων που συμπληρώνονται για τα πλημμυρικά γεγονότα και της μεθοδολογίας αποθήκευσής τους. Στο τέταρτο κεφάλαιο, αναφέρονται οι πηγές που χρησιμοποιήθηκαν για τη συμπλήρωση των πεδίων της βάσης. Στη συνέχεια περιγράφεται η χωρική και χρονική στατιστική ανάλυση του συνόλου των επεισοδίων που περιλαμβάνονται στη βάση και τα αποτελέσματά της. Στο πέμπτο κεφάλαιο, περιγράφεται η προτεινόμενη "ταυτότητα" για τα πλημμυρικά επεισόδια και δίνονται παραδείγματά της για την κατανόησή τους, καθώς και για την περαιτέρω εισαγωγή πληροφοριών σε αυτές. Ακόμη, γίνεται αναφορά στις πηγές πληροφοριών που χρησιμοποιήθηκαν κατά τη διαδικασία συμπλήρωσης των "ταυτοτήτων" και στα προβλήματα που αντιμετωπίστηκαν. Στο έκτο κεφάλαιο, το οποίο είναι και το τελευταίο, συγκεντρώνονται όλα τα συμπεράσματα, οι παρατηρήσεις και οι διαδικασίες που προέκυψαν κατά τη διάρκεια εκπόνησης της παρούσας μεταπτυχιακής εργασίας. Τέλος, γίνονται προτάσεις για περαιτέρω εξέλιξη της ανάλυσης των πλημμυρικών γεγονότων., The subject of this thesis is, firstly, the description and the analysis of the historical flood database, as it is defined by the Directive 2007/60/EC concerning the floods, and creating an "identity" for the flood episodes contained therein. The ultimate goal of creating this identity is to link the disasters of each flood to the amount of rainfall that fell on the day of the flood. The first chapter is an introduction to the incidence of floods in Greece, but also a reference to the floods recorded in Greek mythology. The purpose of the thesis is defined, as well as the prototype points. The second chapter analyzes the Directive 2007/60/EC, describing its stages of implementation, the key points of the report and the creation of the historical database in the preliminary flood risk assessment. The third chapter describes the utility and necessity of historical flood database. The fields required for the flood events and the storage methodology is described. In the fourth chapter, there is a reference to the sources used to collect information for the database. The spatial and temporal statistical analysis of all episodes included in base and its effects is described. The fifth chapter analyzes the proposed "identity" for flood incidents and examples are given for better understanding. Also, it refers to the sources of the information used in the filling procedure of the "identities" and the problems encountered. In the sixth chapter, which is the last one, all findings, observations and procedures that emerged during preparation of this thesis are collected. Finally, suggestions are made for further development of the analysis of flood events., Αλκμήνη Δ. Αλεξίου

Cassino beach, located in southern Brazil, is a very fine sand beach with morphodynamic stages ranging from dissipative to intermediate. This beach can display up to three sand bars which are active during high energy events. Since the beach is located in a microtidal area, flood events are mainly caused by storm surges which can reach 1.8 m. During such events the highest rates of beach erosion are observed. A series of six years (from March 2005 to February 2011) of data from video images have been used to study the nearshore morphodynamic behavior. Daily data of sandbars and waterline position were obtained from these images. The generated data was analyzed in order to recognize flood events patterns as well as patterns of beach morphodynamic both during flood events and during normal conditions. Forty seven flood events were identified, 53% during winter, 24% during autumn, 17% during spring, and 6% in the summer. The average duration of events is 1.5 days. During this period, the whole system is migrating offshore in a rate of 9 m/year. Wavelet analysis showed a gradation of frequencies that govern the variability of the surf zone features. Closer to the beach high frequencies processes (associated with tides and meteorological forcing) have larger influence than further offshore, where longer processes gain importance.

International audience; This article draws on empirical material to reflect on what drives rapid change in flood risk management practice, reflecting wider interest in the way that scientific practices make risk landscapes and a specific focus on extreme events as drivers of rapid change. Such events are commonly referred to as a form of creative destruction, ones that reveal both the composition of socioenvironmental assemblages and provide a creative opportunity to remake those assemblages in alternate ways, therefore rapidly changing policy and practice. Drawing on wider thinking in complexity theory, we argue that what happens between events might be as, if not more, important than the events themselves. We use two empirical examples concerned with flood risk management practice: a rapid shift in the dominant technologies used to map flood risk in the United Kingdom and an experimental approach to public participation tested in two different locations, with dramatically different consequences. Both show that the state of the socioenvironmental assemblage in which the events take place matters as much as the magnitude of the events themselves. The periods between rapid changes are not simply periods of discursive consolidation but involve the ongoing mutation of such assemblages, which could either sensitize or desensitize them to rapid change. Understanding these intervening periods matters as much as the events themselves. If events matter, it is because of the ways in which they might bring into sharp focus the coding or framing of a socioenvironmental assemblage in policy or scientific practice irrespective of whether or not those events evolve the assemblage in subtle or more radical ways.; Este artículo se basa en material empírico para reflexionar sobre lo que impulsa cambios rápidos en la práctica de manejo del riesgo de inundaciones, reflejando un interés más amplio en el modo como las prácticas científicas construyen paisajes de riesgo y se enfocan de manera específica en eventos extremos como los que impulsan cambios rápidos. A tales eventos comúnmente se les refiere como una forma de destrucción creativa, aquello que revela la composición de ensambles socio-ambientales y provee una oportunidad creativa para rehacer tales ensambles de maneras alternadas, cambiando así rápidamente la política y la práctica. Basándonos en un pensamiento más amplio de la teoría de la complejidad, argüimos que lo que ocurra entre eventos puede ser tan importante, si no más, que los eventos mismos. Utilizamos dos ejemplos empíricos preocupados con la práctica del manejo de riesgo de inundación: un cambio rápido en las tecnologías dominantes usadas para cartografiar el riesgo de inundación en el Reino Unido, y un enfoque experimental para participación del público puestas a prueba en dos diferentes localizaciones, con consecuencias dramáticamente diferentes. Ambas muestran que el estado del ensamble socio-ambiental en el que los eventos tienen lugar importa tanto como la magnitud de los propios eventos. Los períodos entre los cambios rápidos no son simplemente períodos de consolidación discursiva sino que involucran la mutación en curso de tales ensambles, que podrían sensibilizarlos o desensibilizarlos hacia el cambio rápido. Entender estos períodos intermedios importa tanto como los propios eventos. Si los eventos importan, eso se debe a las maneras como ellos podrían poner en claro foco la codificación o la enmarcación del ensamble socio-ambiental en políticas o en práctica científica, así sea que tales eventos hagan evolucionar o no el ensamblaje de manera sutil o más radical.; 本文运用经验材料, 反映什麽驱动了洪水风险管理实践中的快速变动, 并更广泛地反映科学实践聚焦风险地景与特定极端事件做为快速改变的驱动力之方式。这些事件普遍被认为是一种创造性破坏的形式, 它们揭露了社会环境聚合的构成, 并提供了以另类方式重构这些聚合的创造性机会, 因而急速地改变了政策与实践。我们运用复杂理论中更为广泛的思考, 主张发生在事件之间的事情或许和事件本身同等重要——即便不是更重要的话。我们运用两项有关洪水风险管理实践的经验案例: 英国用以绘製洪水风险的主流科技的急速转向, 以及在两地运用公共参与并造成截然不同后果的实验性方法。两者皆显示, 事件发生地的社会环境聚合情形, 和事件本身的重大性同等重要。剧烈变革之间的时期, 并非仅是巩固论述的时期, 而是涉及该聚合持续不断的变化, 此一变化有可能使之对剧烈改变更加敏感, 抑或失去敏感性。理解上述的中介时期, 与理解事件本身同等重要。如果事件本身重要的话, 那是因为这些事件将政策或科学实践中社会环境聚合的识别或框架带入关注核心的方式, 而非与这些事件是否以较为隐匿或更激进的方式改变聚合有关。

International audience; Water draining from a large agricultural catchment of 1 110 km2 in southwest France was sampled over an 18-month period to determine the temporal variability in suspended sediment (SS) and dissolved (DOC) and particulate organic carbon (POC) transport during flood events, with quantification of fluxes and controlling factors, and to analyze the relationships between discharge and SS, DOC and POC. A total of 15 flood events were analyzed, providing extensive data on SS, POC and DOC during floods. There was high variability in SS, POC and DOC transport during different seasonal floods, with SS varying by event from 513 to 41 750 t; POC from 12 to 748 t and DOC from 9 to 218 t. Overall, 76 and 62% of total fluxes of POC and DOC occurred within 22% of the study period. POC and DOC export from the Save catchment amounted to 3090 t and 1240 t, equivalent to 1·8 t km−2 y−1 and 0·7 t km−2 y−1, respectively. Statistical analyses showed that total precipitation, flood discharge and total water yield were the major factors controlling SS, POC and DOC transport from the catchment. The relationships between SS, POC and DOC and discharge over temporal flood events resulted in different hysteresis patterns, which were used to deduce dissolved and particulate origins. In both clockwise and anticlockwise hysteresis, POC mainly followed the same patterns as discharge and SS. The DOC-discharge relationship was mainly characterized by alternating clockwise and anticlockwise hysteresis due to dilution effects of water originating from different sources in the whole catchment.

The aim of this paper is evaluation of hydrological regime of the upper part of Lužnice River basin. Upper stream of the Lužnice river represents low intensity of modification. Larger part of the river is a meandering stream with many ponds and pools in the floodplain where the safe retention of water during floods is possible. First part of this paper focus on detailed area hydrography description. The main part concentrates to hydrological regime. The methodology of this research is based on statistical evaluation of the longtime data series from the Pilař station. Flood events and dry periods are analyzed during the past 46 years. Detailed discharge measurements (realized in this area by Faculty of Science, Department of Physical Geography and Geoecology) are used for recent flood evaluations. Higher occurrence of floods and dry periods was identified in the past 10 years.

One of the aims of my dissertation is to evaluate extreme rainfall - runoff conditions in elected experimantal basins of Czech Hydrometeorological Institute in region of Jizerské hory in hydrometeorological period 2009. I would like to evaluate effect of different geografical conditions in particular basins in the course of one year in details analysis of individual events. I pay attention to define model territory and basic description of his physical - geographical condition in introduction of my dissertation. I describe conditions of model area detailed, because this conditions are involved in formation of extreme flowing situations. Summary of this dissertation build up base of my dissertation. Summarization of bibliography was exetuted assigned subject. I composed generate and rainfall - runoff conditions of rainfall - runoff situations in my dissertation. This teoretical knowledges were used in practical section where I showed detailed analysis of three chosen hydrological events. It regards floods, which include spring snow melting, flash flood rised to rainfall downfalls and generated rainfalls long-range character. I describe impact of different geografical conditions at base of obtained results in each of seven experimantal basins of Czech Hydrometeorological Institute in the course of...

Innovative coupling between the soil–vegetation–atmosphere transfer (SVAT) model Interactions between Soil, Biosphere, and Atmosphere (ISBA) and the hydrological model TOPMODEL has been specifically designed for flash-flood forecasting in the Mediterranean area. The coupled model described in this study combines the advantages of the two types of model: the accurate representation of water and energy transfer between the soil and the atmosphere within the SVAT column and an explicit representation of the lateral transfer of water over the hydrological catchment unit. Another advantage of this coupling is that the number of parameters to be calibrated is reduced by two, as only two parameters instead of four parameters concern the TOPMODEL formulation used here. The parameters to be calibrated concern only the water transfer. The model was calibrated for the simulation of flash-flood events on the three main watersheds covering the French Cévennes–Vivarais region using a subset of past flash-flood events having occurred since 2000. The complementary subset of flash-flood events was then used to carry out an objective verification of the coupled model after calibration. The evaluation on these six independent past flash-flood events shows satisfactory results. The comparison of the observed and simulated hydrographs demonstrates that no flash-flood peaks are missed. Relevant information for flash-flood forecasting can always be inferred from the simulations, even for those with quite poor results, making the system useful for real-time and operational flash-flood forecasting.

Present days are characterized by raising awareness of natural hazards, especially the risk of flood events. Extreme floods are connected with large - scale material damage and also endanger human lives. That's why the issue of flood formation and its possibility of forecasting has became disccused topic these days. Research of passed floods provides principles of effective flood protection in specific area. The main aim of this thesis is to analyse flood events that passed in the uper Opava river basin, concretely the source area containing the Černá, Střední and Bílá Opava river basins. This analysis refers about the flood frequency, different seasonal regime of floods occurence and looks for the relationship between atmospheric conditions and origin of flood events in the period of 1963 to 1997. Part of this thesis also summarizes main types of floods raised in the source area and compares different flood threat of the Černá, Střední and Bílá Opava rivers. There is also mentioned some basic differences of drainage formation, natural conditions and rainfall distribution in specific catchment area.

International audience; The temporal variability of nitrate transport was monitored continuously in a large agricultural catchment, the 1110 km2 Save catchment in south-west France, from January 2007 to June 2009. The overall aim was to analyse the temporal transport of nitrate through hydrological response during flood events in the catchment. Nitrate loads and hysteresis were also analysed and the relationships between nitrate and hydro-climatological variables within flood events were determined. During the study period, 19 flood events were analysed using extensive datasets obtained by manual and automatic sampling. ThemaximumNO3 − concentration during flood varied from 8.2 mg l−1 to 41.1 mg l−1 with flood discharge from 6.75 m3 s−1 to 112.60 m3 s−1. The annual NO3 − loads in 2007 and 2008 amounted to 2514 t and 3047 t, respectively, with average specific yield of 2.5 tkm−12 yr−1. The temporal transport of nitrate loads during different seasonal flood events varied from 12 t to 909 t. Nitrate transport during flood events amounted to 1600 t (64% of annual load; 16% of annual duration) in 2007 and 1872 t (62% of annual load; 20% of annual duration) in 2008. The level of peak discharge during flood events did not control peak nitrate concentrations, since similar nitrate peaks were produced by different peak discharges. Statistically strong correlations were found between nitrate transport and total precipitation, flood duration, peak discharge and total water yield. These four variables may be the main factors controlling nitrate export from the Save catchment. The relationship between nitrate and discharge (hysteresis patterns) investigated through flood events in this study was mainly dominated by anticlockwise behaviour.

The aim of this thesis is to evaluate flood flows in the basin Jenín stream. Part of this work is the description of the territory that I prepare from the perspective of the geomorphological, geological, pedological, hydrological, agro-natural, climatic and biotic. For flood flows, I used data for the hydrological year 2009 that I acquired from Thomson weir, where meters are installed. In the first part of this thesis, I conducted field research the functionality of the drainage group. The result is data that recorded performance shafts. In the next section I dealt with the evaluation of quantitative indicators of precipitation, precipitation operation in relation to catchment flows on the cap and providing a critical period in terms of the spring thaw.

Swiss Journal of Geosciences, 103 (1), ISSN:1661-8734, ISSN:1661-8726

A comparison among models were performed. In the present report, the results of the first attempt to modelling flood events by using the SWAT model was presented .

Pirítica Ibérica (FPI), una de las principales regiones metalogénicas del mundo, por lo que ambos ríos están profundamente degradados por los lixiviados generados por el Los ríos Tinto y Odiel discurren en su mayor parte por materiales de la llamada Faja proceso conocido como drenaje ácido de mina (AMD).El río Tinto recibe, en relación a su caudal, aproximadamente el doble de contaminantes que el Odiel, por ello las condiciones en el Tinto son más extremas. En ambos sistemas los bajos valores de pH, muy constantes a lo largo del año se deben a las reacciones de hidrólisis de Fe disuelto, y posibilita la presencia en disolución de elevadas concentraciones de metales tóxicos. La calidad del agua de los ríos Tinto y Odiel sigue un patrón estacional, la concentración de la mayoría de elementos es menor durante el invierno y aumenta progresivamente durante la primavera y el verano.---------------------------The Tinto and Odiel rivers drain one of the most important mining regions in the world, the Iberian Pyrite Belt (IPB), an as a consecuence both rivers are deeply affected by acid mine drainage (AMD). The Tinto river receives, in relation to its discharge, twice as much pollutants than the Odiel, being this the reason why more extrem conditions can be found in the Tinto. Low pH values in both systems througthout the year are due to Fe hydrolysis reactions that buffer pH and contribute to reach high dissolved toxic metal concentrations. Water quality in both rivers follows a seasonal pattern. Most elements show lowest values during winter, increasing progressively in spring and summer.

Dissolved major and trace element concentrations were determined from November 2000 to December 2003 in the lower Rhone River (France). Subsurface water samples were collected about twice a month and more regularly during flood events. An unusual trend was observed for As, Sb, Ni and Ba concentrations which increased with river discharge at the beginning of the floods, in contrast with other elements. Variations of Sb/Na and As/Na molar ratios show that it is related to higher contributions of waters from western tributaries of the Rhone River enriched in As, Sb, Ni and Ba due to ancient mining activities. These unusual variations of dissolved element concentrations are thus interpreted as mark of a water mass origin within the watershed.

This paper presents the assessment of the efficiency of the main biological nitrogen transformation processes in a shallow well-oxygenated river and conditions under which they are active and stabilise. The process dynamics was studied with the help of mathematical modelling of 2 years on-line data series measured in a reach of the Toess River, Switzerland. The algal nitrogen uptake was very stable and unaffected by most but frequent flood events. Daylight photosynthetic nitrogen uptake stabilised at 6 mg N m −2 streambed h −1 (15 °C), dark uptake on storage products at rates of 0.5–2.5 mg N m −2 streambed h −1 . Nitrogen uptake by heterotrophic bacteria in the hyporheic zone was relatively constant at a level of 1.5–3.5 mg N m −2 streambed h −1 . Streambed nitrification could establish only during periods with average an daily concentration of at least 0.3 g NH4-N m −3 in river water for several weeks. The maximum nitrification rate was 35 mg N m −2 streambed h −1 for 3 g NH4-N m −3 . The effects of reduced nitrification in the WWTP and of river banks shading on a sudden ammonium peak were simulated. A river reach endangered by ammonium spills should be kept open to sun to favour ammonium uptake by algae. In-stream nitrification reduces ammonium peaks efficiently but leads to toxic nitrite concentrations.

The island of Sardinia is a typical semiarid Mediterranean region, characterised by a dense network of temporary rivers and streams that play a crucial role in feeding water bodies such as reservoirs, lagoons or coastal areas. In such ecosystems, which are extremely sensitive to point and diffuse sources of pollutants, the annual period of streamflow affects the water quality and quantity of downstream water resources, especially during the first flood events that follow the dry season. Moreover the high nutrient transport may lead to eutrophication phenomena in receiving water bodies. The impact of flood events have been investigated in the Mulargia, a representative temporary river located in the south-eastern part of Sardinia. It is the largest natural tributary feeding the Mulargia reservoir which supplies most of the water supplied to the Campidano plain both for civil, agricultural and industrial purposes. A field sampling campaign has been carried out for one year (Sept 2003-Aug 2004) in selected stream reaches, collecting hydrometric, meteorological, chemical-physical and biological data on water and sediment quality. The installation of flow-switched automatic samplers, on line probes (pH, tempera- ture, dissolved oxygen and conductivity) and rain gauges for continuous precipitation records, allowed the collection of numerous and frequent data within a well defined representative flood. The impact of the flood event on water quality dynamics has been investigated analysing the pollutant trends in relation to the flows patterns. Changes of sediment composition and in microbial communities have been also observed and related to hydrology. Runoff events were strongly influenced by the geomorphology of the basin. Shale rocks, characterise the entire area, limiting permeability and giving very low infiltra- tion losses and consequently high runoffs from all the basin, and particularly from cultivated lands. With regard to sediment and particulate matter transport, the im- portance of the first autumn flood event, occurred after the summer dry period, has been highlighted in this work. Winter and spring floods did not affect water quality as strongly, even when discharges were higher. Although in terms of flow the first flood only represented 10% of the annual runoff, it was responsible for exporting more than 30% of the annual suspended solids load. Sediment characteristics, such as water content, AFDW, C, N and P content showed low variability in time. However, sediment composition in 2004 showed concentration values lower than in the previous drier year. Local inputs affected chemical composi- tion and mainly bacterial abundance and activity. It is hypothesised that chemical and biological processes in river bed-sediments, although not influencing water quality during high floods, may significantly affect the characteristics of transported sedi- ments after long dry periods. The SWAT model has been applied to the catchment in order to simulate at basin scale the impact of pollution derived from diffuse and point sources during flood. The outputs from the simulation, evaluated against the measured data regarding flow and water quality, confirmed the quality of the simulation. Thanks to the semi-distributed approach, the application of the model allowed analysis of the different scenarios orig- inating from different pollution levels and the simulation results have been interpreted to plan management strategies aimed at reducing pollution impacts. Furthermore the simulation highlighted some peculiarities inherent in temporary rivers (i.e. related to sediment delivery, point source contribution to baseflow, rain data rep- resentativeness, etc) and also some limitations in the use of the SWAT model in these catchments, suggesting some new/modified approaches and features that could be use- ful to develop and include in the model. The present work have been carried out within "TempQsim"(EVK1-CT2002-00112), a project financed by the EU with the final aim to provide advanced tools to improve the efficiency of integrated water management in semiarid river catchments

Περίληψη: Η παρούσα μεταπτυχιακή διατριβή επικεντρώνεται στην εκτίμηση της πλημμυρικής επικινδυνότητας στην Ελλάδα με χρήση πολυκριτηριακής ανάλυσης σε περιβάλλον Γεωγραφικών Συστημάτων Πληροφοριών (GIS). Ως περιοχή μελέτης έχει επιλεγεί ο Ελλαδικός χώρος, που ιστορικά έχει πληγεί από σειρά σημαντικών και καταστροφικών πλημμυρών. Στην παρούσα μεταπτυχιακή εργασία γίνεται μια προσπάθεια εκτίμησης της πλημμυρικής επικινδυνότητας στον Ελλαδικό χώρο, σε περιβάλλον Γεωγραφικών Συστημάτων Πληροφοριών (GIS), με χρήση διαφόρων θεματικών χαρτών-παραγόντων που εμπλέκονται στη δημιουργία ενός πλημμυρικού φαινομένου. Πιο συγκεκριμένα, για την εύρεση του πλημμυρικού κινδύνου στην περιοχή μελέτης, πραγματοποιήθηκε χαρτογράφηση και απεικόνιση επτά διαφορετικών θεματικών χαρτών σε περιβάλλον ΓΣΠ. Οι παράγοντες που συνδυάζονται σε περιβάλλον ΓΣΠ προκειμένου να προσδιοριστούν χωρικά οι περιοχές εκείνες, οι οποίες είναι πιο επιρρεπείς σε πλημμυρικά φαινόμενα είναι: α) η ένταση της βροχόπτωσης, β) το υψόμετρο, γ) η κλίση του εδαφικού ανάγλυφου, δ) οι χρήσεις γης, ε) η συσσώρευση επιφανειακής ροής, στ) η εδαφική διαβρωσιμότητα και ζ) η υδατοϊκανότητα του εδάφους. Η πλημμυρική επικινδυνότητα για κάθε ένα από αυτούς τους παράγοντες κατηγοριοποιείται σε πέντε τάξεις: Πολύ Χαμηλή (1), Χαμηλή (2), Μέτρια (3), Υψηλή (4), και Πολύ Υψηλή(5). Εν συνεχεία, οι παραπάνω παράγοντες συνδυάζονται και επεξεργάζονται με χρήση κατάλληλων αλγορίθμων Τεχνικών Νευρωνικών Δικτύων (ΑΝΝ) στη Γλώσσα Προγραμματισμού Matlab (εργαλειοθήκη nntool). Αναλυτικότερα, στα πλαίσια της εκπαίδευσης των Τεχνιτών Νευρωνικών Δικτύων συνδυάζεται η χωρική κατανομή των ιστορικών πλημμυρικών σημείων στον Ελλαδικό χώρο με τους προαναφερόμενους εφτά εμπλεκόμενους στην δημιουργία πλημμυρικών φαινομένων θεματικούς χάρτες. Προσδιορίζεται έτσι χωρικά η πλημμυρική επικινδυνότητα στην Ελληνική επικράτεια. Τα τελικά αποτελέσματα επαληθεύτηκαν από ιστορικά πλημμυρικά γεγονότα που έχουν συμβεί στον Ελλαδικό χώρο τα τελευταία 100 χρόνια.