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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.
21

Hydrological and chloride transport processes in a small catchment of the Norrström Basin : a MIKE SHE modelling approach

Liu, Zhuhuan, Zhou, Chen January 2019 (has links)
Water is ubiquitous on our planet and constitutes a vital part of ecosystems. It supports the life of all beings on the earth while simultaneously evokes water-related issues such as water shortage, water contamination. As UN advocates, a globally shared blueprint for available clean water is depicted in Sustainable Development Goals (SDGs). However, there still exists a gap between current water management situations and our sustainable goals Modelling based on Hydro-Meteorological Data provides a way to understand regional hydrological processes and monitor environmental chemistry changes, especially for anthropogenic pollution. Furthermore, hydrological models make it possible to predict changes in water quantity and quality, under the context of climate change. The study area of this project is located in the Kringlan catchment, Norrström basins, occupying an area of 54.5 km2. The local discharges merge into Rastälven river and flow to the east, eventually discharging into the Baltic Sea. This project builds up a water balance model based on the meteorological data in the time frame from 2011 to 2012. The water balance model is calibrated to accurately simulate realistic hydrological components interactions, during each process, various parameters have been tested and adjusted to improve model robustness. Meanwhile, the project tries to strike a balance between the complexity of the model and amount of time it takes to run the model. The calibrated model is also validated to ensure model performance using statistical analysis. Additionally, a particle tracking model for the saturated zone is developed on the basis of the water balance model. Chloride is chosen as the trace element due to its feature of unreactive in ecological systems. The model results could also provide a value to groundwater age estimation. Suggested by previous researches targeting the area, leakage from vegetation and forest soil in this catchment have contributed to imbalances in local Cl- budgets. An internal source of chloride from soil leaching is specified in the model at the same time with an external source from stream discharge. The coupled modelling through the application of MIKE SHE software and calibration process help us to understand dynamic processes of hydrological modelling and chloride particle transport in the Kringlan catchment. A future improvement to consider is extending the current model boundary to a larger area and introducing more reference data. It is also possible to establish a fully integrated solute transport model to investigate Chloride transport in the catchment. / Vatten ersätter en viktig del av ekosystemet men det framkallar vattenrelaterade problem som vattenbrist och vattenförorening samtidigt. Emellertid finns det fortfarande ett gap mellan nuvarande vattenhanteringssituationer och våra hållbara mål. Modellering baserad på meteorologiska data erbjuder en möjlighet att förstå regionala hydrologiska processer och övervaka förändringar av miljömässiga kemikalier, särskilt för antropogena föroreningar. Dessutom finns det en hög potential för att förutse förändringar i vattenmängd och kvalitet med hydrologiska modeller, i samband med klimatförändringar. Studieområdet ligger i Kringlans upptagningsområde som ett av Norrström basins, med en yta på 54,5 km2. De lokala utsläppen sammanfogas i Rastälven och strömmar österut, så småningom mynnar i Östersjön. Detta projekt bygger upp en vattenbalansmodell baserad på meteorologiska data inom tidsramen från 2011 till 2012. Vattenbalansmodellen är kalibrerad för att exakt simulera realistiska hydrologiska komponentinteraktioner. För att förbättra modellens robusthet har olika parametrar testats och anpassats under varje process. Samtidigt försöker projektet att hitta en balans mellan modellens komplexitet och hur lång tid det tar att driva modellen. En partikelspårningsmodell för den mättade zonen har utvecklats med utgångspunkt i vattenbalansmodellen. Klorid används som spårämne eftersom det är inert i ekologiska system. Modellsresultaten kan också ge ett värde för grundvattenberäkningen. Tidigare undersökningar inriktade på området föreslår att läckage från vegetation och skogsmark i detta avrinningsområde har bidragit till obalanser i lokala Cl- budgetar. Med hjälp av MIKE SHE modellen har vi undersökt dynamisk process för hydrologisk modellering och kloridpartikelspårning i Kringlan avrinningsområde. Vad som kan gör i framtiden är att förlänga den nuvarande modellgränsen till ett större område med mer referensdata. Det är också möjligt att upprätta en fullständigt integrerad lösningsmodell för att undersöka kloridtransporter i ett avrinningsområde.
22

Etude de la vulnérabilité des eaux aux produits phytosanitaires : indicateur environnemental et modèle mécaniste, en vue d'une meilleure gestion du bassin versant de la Leysse (Savoie)

de Bruyn, Bertrand 30 January 2004 (has links) (PDF)
Le bassin de la Leysse a fait l'objet d'une modélisation mécaniste distribuée fondée sur le logiciel MIKE SHE, qui a permis de reproduire l'hydrologie par simulation des karsts, des nappes et des terrains à fort ruissellement. Un modèle de transport de substance chimique a permis de simuler des pollutions potentielles : par déversements accidentels ou diffuses par les produits phytosanitaires. Il montre le rôle prépondérant des eaux de surface pour le transfert des pollutions. Un indicateur environnemental de vulnérabilité des eaux de surface aux produits phytosanitaires, VESPP, de formulation simple et aux paramètres aisés à recueillir, a été évalué spatialement sur le bassin. Ses résultats sont en bon accord avec ceux du modèle. Ainsi validé, l'indicateur et sa méthode floue d?analyse des imprécisions peuvent être utilisés par des gestionnaires. Sa mise en place dans un logiciel d'aide à la décision a été réalisée sur la base du S.I.G. MapInfo.
23

Testing and Refining a Unique Approach for Setting Environmental Flow and Water Level Targets for a Southern Ontario Subwatershed

Beaton, Andrew 15 August 2012 (has links)
In this study Bradford’s (2008) approach for setting ecological flow and water level targets is tested and refined through application within the Lake Simcoe Region Conservation Authority’s (LSRCA) subwatershed of Lover’s Creek. A method for defining subwatershed objectives and identifying habitat specialists through expert input is proposed and tested. The natural regime of each streamflow and wetland site is characterized along with the hydrological alteration at each site. Potential ecological responses to the hydrologic alterations are then hypothesized for the different types of changes calculated at each site. Methods for setting overall ecosystem health and specific ecological objective flow targets are proposed and tested. These targets are integrated into a flow regime for each site and a process for using this information for decision making is suggested. Flow magnitude quantification is attempted using hydraulic modelling and sediment transport equations, however the data used were found to be inadequate for this application. The accuracy of the targets developed using the method presented in this paper is mainly limited by the accuracy of the hydrological model and quantified flow magnitudes. Recommendations for improving these components of the assessment are made. The unique approach and recommendations presented in this paper provide explicit steps for developing flow targets for subwatersheds within the LSRCA. This research contributes toward the advancement of EFA within the LSRCA, which provides opportunity for enhanced protection and restoration of ecosystem health across the watershed. / Lake Simcoe Region Conservation Authority

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