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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Impact of land use change and agricultural practices on aquatic microbial diversity and functioning in a tropical system / Impact du changement d'utilisation des terres et des pratiques agricoles sur la diversité et le fonctionnement microbiens aquatiques dans un écosystème tropical

Le, Thi Huong 17 October 2018 (has links)
L'utilisation des terres (UT) vers des pratiques agricoles non durables amplifie la dégradation et l'érosion des sols, et la perte de leur diversité microbienne. Cependant, les impacts du changement d'UT sur la structure de la communauté microbienne dans les cours d'eau adjacent restent mal compris, en particulier dans les écosystèmes tropicaux. Grâce à des expériences contrôlées et à des études in situ, j'ai évalué comment différentes pratiques agricoles et d'UT, via des processus hydrologiques, affectent la quantité et la qualité de la matière organique dissoute dans le cours d'eau et la structure de la communauté microbienne associée. Les résultats de ce travail montrent l'importance de considérer à la fois l’UT passée et présente avec les processus hydrologiques lors de l'évaluation de la diversité microbienne et des capacités métaboliques des cours d’eau. Alors que les expériences dans des conditions contrôlées (micro- et mésocosmes) ont permis de distinguer l'importance relative des ruissèlements d’eau de surface sur la structure bactérienne du milieu aquatique, l'approche in situ a permis de donner une vision intégrée de ces processus à l'échelle du bassin. Cela a mis en évidence la nécessité d'utiliser des pratiques de gestion durable d'UT si nous souhaitons atténuer les impacts sur les systèmes aquatiques en aval / Land use (LU) change towards non-sustainable agricultural practices enhances soil degradation, erosion, and the loss of soil microbial diversity. However, the impacts of LU change on in-stream microbial community structure remain poorly understood, particularly in tropical ecosystems. Through controlled experiments and in situ investigations, I assessed how different LU and agricultural practices, via hydrological processes, affect the quantity and quality of stream dissolved organic matter and associated microbial community structure. The results of this work show the importance of considering both past and present LU along with hydrological processes when assessing stream microbial diversity and metabolic capacities. While the experiments in controlled conditions (micro- and mesocosms) allowed disentangling the relative importance of direct overland flow and soil community on stream bacterial structure, the in situ approach gave an integrated view of these processes at the basin scale. This emphasizes the need to use sustainable LU management practices if we wish to mitigate off-site impacts on downstream aquatic systems
302

Modélisation des transferts de pesticides à l'échelle des bassins versants en période de crue / Modelling pesticide transfers at catchment scale during flood events

Boithias, Laurie 04 April 2012 (has links)
Les concentrations élevées en pesticides dans les eaux de surface drainant des bassins versants agricoles sont devenues une préoccupation majeure en Europe depuis une cinquantaine d'années. Les pesticides sont transférés dans l'environnement par différentes voies (le ruissellement de surface et de sub-surface, le flux de nappe), soit en solution soit adsorbés aux particules de sol en suspension dans l'eau. Les eaux de ruissellement et de percolation entraînent avec elles des charges de contaminants dont les concentrations en solution peuvent s'avérer toxiques pour la faune et la flore aquatique et rendre l'eau impropre à la consommation humaine si le réseau de drainage est une source de captage pour l'alimentation en eau potable. Les crues constituent donc des événements hydrologiques de première importance dans la contamination des eaux continentales par les pesticides. Les objectifs de cette thèse ont été de (1) caractériser, à l'aide d'un modèle agro-hydrologique, la dynamique des transferts de pesticides à l'échelle du bassin versant dans une région agricole, notamment en période de crue ; (2) identifier les facteurs de contrôle du transfert de pesticides et (3) améliorer, le cas échéant, les équations formalisées dans le modèle. Deux approches ont été menées de front afin de répondre aux questions posées : l'analyse de données mesurées et modélisées sur le bassin versant agricole de la Save (sud-ouest de la France). Une étude de faisabilité réalisée en préliminaire a montré que le modèle Soil and Water Assessment Tool (SWAT - Arnold et al., 1998) était adapté à la modélisation du transfert de pesticides, dans les phases dissoute et particulaire, à l'échelle du bassin versant. L'hydrologie et les concentrations à l'exutoire des phases dissoute et particulaire (respectivement les nitrates et les matières en suspension) ont été calibrées. Les voies privilégiées de transfert des pesticides en fonction des conditions hydrologiques ont été identifiées. La modélisation a ensuite été mise en œuvre avec des itinéraires techniques plus détaillés en entrée du modèle et des mesures sub-journalières de pesticides en crue. Les différentes voies de transfert des pesticides dans les deux phases, ainsi que leurs facteurs de contrôle environnementaux, ont été étudiés. Deux facteurs de contrôle, respectivement dépendant des pratiques agricoles (la date d'application des pesticides, qui est un facteur anthropique) et intrinsèque aux molécules de pesticides (le coefficient Kd de partition entre phases dissoute et particulaire, qui est un facteur physico-chimique) ont été abordés plus en détail. Le rôle de la typologie du bassin versant sur les transferts est discuté. Des cartes de risque de contamination des eaux de surface par les pesticides sont présentées pour le bassin de la Save. Dans la perspective d'améliorer le formalisme des modèles de transfert des pesticides, une équation qui relie le coefficient Kd au coefficient de distribution octanol/eau Kow et à la concentration en matières en suspension a été proposée. / Rising pesticide levels in streams draining intensively managed agricultural land has become a widespread problem throughout Europe in recent decades. Pesticides are transferred into the environment through various pathways (surface and sub-surface runoff, groundwater return flow), either in solution or sorbed onto particles. Runoff and percolating water carry contaminants loads which concentrations in solution may be harmful to terrestrial and aquatic ecosystems rendering water unfit to human consumption if the draining network is a source for drinking water. Floods are hydrological events of major importance in continental waters contamination by pesticides. The objectives of this PhD thesis were (1) to characterise pesticides transfer dynamics at catchment scale in an agricultural area during floods; (2) to identify the factors controlling pesticides transfer and (3) to improve modelling by changing formalism with more suitable equations. Two approaches were set up: analysing both measured and simulated data sets, stemming from the River Save catchment (south-western France). A preliminary feasibility study showed that the Soil and Water Assessment Tool (SWAT - Arnold et al., 1998) was adapted for pesticides transfer modelling in both dissolved and sorbed phases, at catchment scale. Water discharge, dissolved and sorbed phases (respectively nitrate and suspended sediments) were calibrated. Pesticides transfer preferred pathways depending on hydrological conditions were identified. Modelling was then carried on more detailed management practices as input and on sub-daily pesticides concentration measurements during flood events. The various transfer pathways in both phases together with the environmental controlling factors were assessed. At last, two controlling factors, respectively depending on management practices (application date, an anthropogenic factor) and on an intrinsic pesticide molecule property (the partition coefficient Kd which is a physico-chemical factor) were studied. The role of catchment typology was discussed. Surface water contamination risk maps were drawn on Save catchment. In order to improve the formalism of pesticide transfer models, an equation was proposed that relates Kd to the octanol/water partition coefficient Kow and to suspended matter concentration.
303

Optimalizace spádových obvodů základních škol ve správních obvodech ORP Třeboň, ORP Jindřichův Hradec a ORP Dačice / Optimizing catchment regions of elementary schools in administrative dictricts of Třeboň, Jindřichův Hradec and Dačice

TOMÍČEK, Filip January 2019 (has links)
This diploma thesis is addressing the issue of elementary schools in Jindřichův Hradec region. This administrative region consists of 3 smaller districts - Třeboň, Jindřichův Hradec and Dačice. Goals of this diploma thesis are to map, to describe and to find solution for actual issues in elementary schools in choosed region. Diploma thesis maps localization of elementary schools and catchment regions, territorial distribution of schoolchildren and existence of school buses and trains in area. All data was processed into tables and maps.
304

Developing Effective Partnerships in Natural Resource Management

Oliver, Peter Edward, n/a January 2004 (has links)
This thesis seeks to understand and improve the effectiveness of partnerships formed by industry, community and government members of natural resource management (NRM) groups. The increasing popularity of partnership-based approaches to NRM is reflected in the rise of landcare, catchment management and other social mobilisation approaches throughout Australia and overseas. This thesis uses critical ethnographic methods to identify the characteristics of effective NRM partnerships and the factors influencing their effectiveness. This research also investigates appropriate methods for evaluating the effectiveness of such relationships and for determining when working in partnership with others may be the most appropriate response to a given NRM problem and context. The critical intent of the study means that it sought not only to understand the nature of such issues but also sought to enlighten and empower participants to improve the practice of partnerships in natural resource management. These characteristics and factors are analysed from three perspectives: the coordinators employed to broker and facilitate community-based NRM groups, the groups themselves and individual group members. This was done in order to reflect the importance of the continuous (re)negotiation of power that characterises long-term group relationships. It also enabled theories of power, cultural transformation, citizen participation, social capital and social learning to be used in the analysis of the NRM partnerships investigated in this study. These concepts were used to develop three tools for analysing NRM partnerships: a pendulum of citizen participation, an NRM citizen participation decision tree, and an NRM partnership typology. The study is based upon the analysis of nineteen cases, predominantly in South East Queensland, which were selected as examples of successful and effective NRM partnerships on the basis of referrals from regional managers and coordinators from State and Local Government. The research design was 'T' shaped, with Phase 1 of the study providing breadth through the analysis of fifteen partnerships. Depth was achieved in Phases 2 and 3. Phase 2 was a long-term ethnographic case study of one catchment management group while Phase 3 comprised a detailed analysis of three issue-specific partnerships formed by this group. These three phases concentrated on the viewpoint of coordinators, NRM groups and participants, respectively. Data on each of the nineteen cases were collected through interviews, field observations, workshops, document analyses and a short questionnaire. Data were analysed qualitatively. All data records were systematically coded to reveal themes and concepts relating to the research objectives from the viewpoints of coordinators, NRM groups and participants. Coding also revealed implications for governments seeking to enter into or to facilitate partnerships with others. The coding and interpretation of this data revealed a suite of twelve characteristics typical of effective natural resource management partnerships. These fell into five groups: (i) definitional characteristics (relating to effectiveness and shared power and responsibility) (ii) relationship characteristics (focusing on social capital building processes; communication; processes for knowledge acquisition and social learning; shared values, intent, action and risk-taking) (iii) participant characteristics (high levels of motivation and realistic expectations); (iv) a context characteristic (that the context is appropriate for a partnership) and (v) an 'outsider' perception characteristic (that the partnership is perceive positively by outsiders). A comparative analysis of cases reveals that only one of the nineteen cases exhibited all twelve characteristics. Importantly, three of these characteristics are not mentioned in the literature reviewed for this thesis. Two of these, share values and shared intent are relationship characteristics. Study findings emphasise that effective NRM partnerships are built on good personal relationships, based on shared values and intent. The third new characteristic is that people outside the partnership should perceive the relationship favourably. Since funds and other resources may be under the control of people outside a partnership, it is important that participants are able to effectively communicate their shared values and intent to others. Five factors were found to be significant in the development of effective partnerships (i) the need for participants and those brokering partnerships to realize that effective partnerships are built on positive personal relationships in which (ii) participants have high levels of motivation for being involved, particularly early in the relationship. The study further revealed that such relationships: (iii) need to be supported by a continuity of adequate funding and resources and (iv) the services of skilled, enthusiastic coordinators who (v) enjoy and are skilled at working in 'grey areas', the constantly changing social and organizational environment that is typical of NRM groups. These findings of the study are synthesized through a critical ethnography which depicts three years in the life of a typical, yet hypothetical, NRM group, the Armstrong Narrows-Yarooba Catchment Management Group (ANY Group). Based on the literature review and the analysis of results from this study, this composite story protects the anonymity of those who have participated in this research. Each of the three vignettes that make up this story contains two sections -As it was and As it could be. This 'double take approach' highlights the critical nature of the ethnography, emphasising how the development of collaborations and partnerships among members of NRM groups may be improved and evaluated. Coordinators, NRM group members and agencies supporting their efforts may use this ethnography as a basis for reflection and deliberation on the development of effective partnerships in natural resource management. Recommendations for how different stakeholders in NRM partnerships may develop the effectiveness of the partnerships they form are provided.
305

The Impacts of Agriculture and Plantation Forestry in a Selection of Upper Catchments of the Strzelecki Ranges, Victoria

Mainville, Daniel Mark, daniel.mainville@dse.vic.gov.au January 2007 (has links)
The intensive nature of land uses in the Strzelecki Ranges poses significant threats to landscape values and water quality. A comprehensive catchment strategy was developed based on sustainability science concepts incorporating the careful management of landscape values, proper land management approaches, and government policy and legislative change to ensure that agriculture, forestry and other land uses become sustainable in this sensitive environment. The readily measurable water quality indicators of turbidity, flow, electrical conductivity, and water temperature were used to determine the impacts of the major land uses in the Strzeleckis. From a water quality perspective, there was a trend of decreasing water quality with increasing intensity in land management. However, from a total sediment load perspective, the forest area contributed the highest total sediment load due to higher volumes of steam flow suggesting that natural processes in the Strzeleckis may remain the principal mechanisms for sediment movement within the catchment. An incidental but significant finding was extensive bioturbation along the riparian zone of the plantation area, the extent of which was not observed in the other catchments. This finding suggested that bioturbation may have been the most significant contributor to poorer water quality flowing from in the plantation catchment. The project developed insights into the major environmental processes active in the upper catchment of the Morwell River. Understanding of the contributions to total sediment loads from natural erosional processes and bioturbation, findings related to the impacts on water quality from agricultural practices, and encountering negligible impacts from conservative timber harvesting practices demonstrate that catchment management approaches need to be tailored to achieve sustainability in land uses across the landscape. Key recommendations include the re-establishment and protection of riparian zones in agricultural catchments, the careful assessment and setting of stream buffer zone widths for timber harvesting operations, and the need for further work to map the extent of natural processes such as bioturbation and stream bank erosion. To mitigate these issues, government policy and legislation will need to focus on the preservation and enhancement of the Crown land riparian zones. Recommended changes to current administrative land management arrangements for these sensitive areas include a move from licensing riparian zones for agricultural practices such as grazing to conservation.
306

From water resources management to integrated water resources management : an analysis of the establishment of new water management organisations in Namibia

Simataa, Faith Auguste January 2010 (has links)
<p>The questions posed in this study address the different processes that were involved in the decision-making and establishment of the water management organisations, the extent of public participation, as well as features of evident governance in implementing the policies. A critical analysis of the role of stakeholders and the various influences they may have in water management will also be examined. The methodology follows a historical study approach. A thorough document review will be done of the policies and related materials around BMCs, where events will be constructed from the findings. Interviews will be conducted for verification purposes, to verify the desktop findings and to assimilate any conflicts of opinion that might have not been documented.</p>
307

Modellering av vattenflöden samt kväve- och fosforkoncentrationer från Krycklans avrinningsområde med HYPE-modellen

Sandqvist, Elin January 2012 (has links)
HYPE-modellen utvecklades som ett hjälpmedel för att uppfylla målet om att alla svenska vattendrag ska ha uppnått åtminstone god ekologisk status år 2015, enligt EU:s ramdirektiv för vatten. I HYPE-modellen delas avrinningsområdet in i markklasser, som definieras utifrån kombinationen av jordart och markanvändning/marktäckeklass. I modellen finns det många parametrar. Vissa av dem är generella för ett större område eller kan hämtas ifrån tidigare forskning, medan andra måste kalibreras för varje avrinningsområde. De parametrar som kalibreras beror i de flesta fall antingen av jordart eller av markanvändning eller marktäckeklass. Syftet i den här undersökningen var att kalibrera HYPE-modellen för ett mindre avrinningsområde samt undersöka avrinningsvägar och utvärdera den utförda kalibreringen. Det undersökta avrinningsområdet kallas Krycklan och ligger i Vindeln kommun i Västerbottens län. Det är ett avrinningsområde som huvudsakligen består av skog, men även innehåller inslag av jordbruksmark och myrmark. Kalibreringen gjordes i två steg, först för ett mindre delavrinningsområde och sedan för hela avrinningsområdet. Två avrinningskalibreringar gjordes för det mindre delavrinningsområdet. Kalibrering A utfördes med ansatsen att få en så hög anpassning som möjligt, med utgångspunkt i det statistiska måttet NSE, vilket är kvadratsumman av residualerna dividerat i den totala kvadratsumman. Kalibrering B gjordes i samråd med SMHI om rimlig storlek på parametervärdena, men gav ett sämre värde på NSE. För hela avrinningsområdet utfördes endast en kalibrering. Ett försök till modellering av kväve- och fosforhalter i avrinnande vatten gjordes även. Resultatet visade att det gick att få en kalibrering av modellen att följa uppmätt flöde väl, även på mikroskala. Skillnaden mellan kalibrering A och kalibrering B var att den första bättre fångade uppmätta flödestoppar, men gav ett för högt basflöde. För både blöta och torra år gick det att få en hög anpassning, men kalibreringen fungerade generellt sätt bättre för blöta år. Det var betydligt svårare för modellen att fånga variationen i kväve- och fosforkoncentrationer, men samband mellan modell och mätvärdena kunde ändå ses. / The HYPE-model was developed as an aid of achieving the goal of all Swedish watercourses should have reached at least well ecological status by the year of 2015, according to the EU Water Framework Directive. In the HYPE model, the catchment is divided into soil classes which are a combination of soil and land use. In the model, there are many parameters. Some of them are general for a larger area or can be obtained from previous research, while others must be calibrated for each catchment. The parameters to be calibrated depend in the most cases either on soil or land uses. The aim of this study was to calibrate and evaluate the HYPE model for a small catchment. The investigated catchment is called Krycklan and is located in the municipality of Vindeln in the province Västerbotten. The catchment consists mostly of forest, but there are also some agriculture and mire. The calibration was made in two steps, first on a small sub-basin and then to the entire basin. Two runoff calibrations were made for the smaller sub-basin. Calibration A was performed with the approach to obtain as high fit as possible, on the basis of the statistical measure NSE, which is the quadrate of the residuals divided in the quadrate of the total quadrate sum. Calibration B was made after consultation with SMHI (The Swedish Meteorological and Hydrological Institute) of the adequate size of the parameter values. For the entire basin only one calibration was performed. An attempt at modelling of nitrogen and phosphorus concentration in runoff was also made. The results showed that it was possible to get the model to follow the measured flow well, even at the micro scale. The difference between calibration A and calibration B was that the first one was better to catch the measured flow peaks, but resulted in too high base flow. For both wet and dry years it was possible to obtain a high fit, but the model generally got better for the wet years. There was much more difficult for the model to capture variation in nitrogen and phosphorus, but the connection between the model and the measurements could still be seen.
308

Bestämning av vattendelare i urban miljö : Metod för avgränsning av avrinningsområden i ArcGIS utgående från dagvattensystemet / Watershed delineation in urban catchment areas : Method for delineating catchment areas in ArcMap based on storm-water drains

Calestam, Karl-Martin January 2013 (has links)
Växande städer leder till att naturmark omvandlas till stadsmiljöer. Det skapar mer hårdgjorda ytor och därmed ökade volymer dagvatten som behöver hanteras. Modellering av dagvattennätet används ofta för att bedöma kapaciteten och risk för översvämningar. Avrinningsområdets storlek är en avgörande parameter för att bedöma hur mycket vatten som kommer till en viss ledning. Traditionellt har automatisk bestämning av avrinningsområden gjorts enbart utifrån topografin. I områden med dagvattennät styr däremot ledningarnas sträckning i första hand hur vattnet rinner, och de följer inte nödvändigtvis terrängen. ArcHydro Tools, som är ett tilläggsprogram till ArcMap, har utvecklats för att beräkna topografiska avrinningsområden. Genom att programmera en tilläggsfunktion i Python har processen i ArcHydro Tools anpassats för att kunna ta hänsyn till dagvattennätet. Dagvattennätet approximerades som vattendrag. Tryckledningar och tunnlar tillåter inte något inflöde av vatten. Därför beskrevs dessa som ändpunkter i ledningsnätet, varifrån vattnet inte rann vidare. Funktionen som skapades i det här examensarbetet tillät att vattnet stannade i dessa punkter, till skillnad från i den ursprungliga metoden. Den utgick istället från att vattnet rann till kanten av det undersökta området, vilket i de här fallen skulle ha resulterat i felaktigt avgränsade avrinningsområden. Tilläggsfunktionen anpassades för att användas som övriga funktioner i ArcMap och testades på data över Lidingö stad. Resultatet visade att det var möjligt att utnyttja topografiskt baserade metoder för bestämning av avrinningsområden så att avgränsningen istället skedde med utgångspunkt i dagvattennätet. Det är ett steg mot att effektivisera processen för bestämning av avrinningsområden för användning vid hydrologisk modellering av dagvattennätet. Behovet av manuell bearbetning minskas. Ett försök att i ArcMap implementera en funktion för efterbehandling av avrinningsområden gjordes också. Funktionen letar upp avrinningsområden som bedöms som för små och lägger ihop dem med ett närliggande område. Avrinningsområden som beräknats med den modifierade metoden har senare använts vid modellering av dagvattennätet i Molkom, Värmland. / Growing populations result in expanding cities. An increase in the amount of impervious surfaces in the area will follow and thereby generate more storm water. The capacity of the drainage system can be evaluated using hydraulic modelling. The model highly depends on the catchment areas, which will determine the water volume each pipe section receive. Watershed delineation is usually done based on the topography. However, if a storm water drainage system is present, it may route the water in a different direction than the slope indicates. ArcHydro Tools is an extension to ArcMap and is commonly used to delineate catchment areas. The method heavily relies on topography during this process. A function has been developed during the course of this project to allow for the drainage system to be the primary source of information for watershed delineation. This function made sure that outlets in the model were to be evaluated as such, even if they happen to be located in the middle of the area of interest. The water is therefore not necessarily routed to the edge of the elevation model, but can be allowed to stay at the appropriate position. In order to do this, the drainage system was represented as a stream network. The new method was applied to test data supplied by Lidingö city, Stockholm, Sweden, and included elevation data and information about the drainage system. The result implies that it is indeed possible to use the drainage system as a base for delineation of catchment areas. A more efficient method of calculating catchment areas will reduce the required amount of manual processing, thereby saving time and resources. Another function, for finishing up the resulting catchment areas, is proposed but not fully implemented. The whole process was used to delineate catchment areas for Molkom, County of Värmland, Sweden. The resulting watersheds were later successfully used for modelling the storm water drains in the area.
309

Untersuchungen zur Besiedlung des Hannoverschen Wendlands von der jüngeren vorrömischen Eisen- bis zur Völkerwanderungszeit / Examinations of Settlement in the Hannoversche Wendland between the late Preroman Iron Age and the Migration Period

Nüsse, Hans-Jörg 23 June 2003 (has links)
No description available.
310

From water resources management to integrated water resources management : an analysis of the establishment of new water management organisations in Namibia

Simataa, Faith Auguste January 2010 (has links)
<p>The questions posed in this study address the different processes that were involved in the decision-making and establishment of the water management organisations, the extent of public participation, as well as features of evident governance in implementing the policies. A critical analysis of the role of stakeholders and the various influences they may have in water management will also be examined. The methodology follows a historical study approach. A thorough document review will be done of the policies and related materials around BMCs, where events will be constructed from the findings. Interviews will be conducted for verification purposes, to verify the desktop findings and to assimilate any conflicts of opinion that might have not been documented.</p>

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