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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.
211

Water Demand and Allocation in the Mara River Basin, Kenya/Tanzania in the Face of Land Use Dynamics and Climate Variability

Dessu, Shimelis B 21 March 2013 (has links)
The Mara River Basin (MRB) is endowed with pristine biodiversity, socio-cultural heritage and natural resources. The purpose of my study is to develop and apply an integrated water resource allocation framework for the MRB based on the hydrological processes, water demand and economic factors. The basin was partitioned into twelve sub-basins and the rainfall runoff processes was modeled using the Soil and Water Assessment Tool (SWAT) after satisfactory Nash-Sutcliff efficiency of 0.68 for calibration and 0.43 for validation at Mara Mines station. The impact and uncertainty of climate change on the hydrology of the MRB was assessed using SWAT and three scenarios of statistically downscaled outputs from twenty Global Circulation Models. Results predicted the wet season getting more wet and the dry season getting drier, with a general increasing trend of annual rainfall through 2050. Three blocks of water demand (environmental, normal and flood) were estimated from consumptive water use by human, wildlife, livestock, tourism, irrigation and industry. Water demand projections suggest human consumption is expected to surpass irrigation as the highest water demand sector by 2030. Monthly volume of water was estimated in three blocks of current minimum reliability, reserve (>95%), normal (80–95%) and flood (40%) for more than 5 months in a year. The assessment of water price and marginal productivity showed that current water use hardly responds to a change in price or productivity of water. Finally, a water allocation model was developed and applied to investigate the optimum monthly allocation among sectors and sub-basins by maximizing the use value and hydrological reliability of water. Model results demonstrated that the status on reserve and normal volumes can be improved to ‘low’ or ‘moderate’ by updating the existing reliability to meet prevailing demand. Flow volumes and rates for four scenarios of reliability were presented. Results showed that the water allocation framework can be used as comprehensive tool in the management of MRB, and possibly be extended similar watersheds.
212

All models are wrong, but some are useful: Assessing model limitations for use in decision making and future model development

Apostel, Anna Maria January 2021 (has links)
No description available.
213

Hydrological and sediment yield modelling in Lake Tana Basin, Blue Nile Ethiopia

Setegn, Shimelis Gebriye January 2008 (has links)
Land and water resources degradation are the major problems on the Ethiopian highlands. Poor land use practices and improper management systems have played a significant role in causing high soil erosion rates, sediment transport and loss of agricultural nutrients. So far limited meas-ures have been taken to combat the problems. In this study a physically based watershed model, SWAT2005 was applied to the Northern Highlands of Ethiopia for modelling of the hydrology and sediment yield. The main objective of this study was to test the performance and feasibility of SWAT2005 model to examine the influence of topography, land use, soil and climatic condi-tion on streamflows, soil erosion and sediment yield. The model was calibrated and validated on four tributaries of Lake Tana as well as Anjeni watershed using SUFI-2, GLUE and ParaSol algo-rithms. SWAT and GIS based decision support system (MCE analysis) were also used to identify the most erosion prone areas in the Lake Tana Basin. Streamflows are more sensitive to the hy-drological response unites definition thresholds than subbasin discretization. Prediction of sedi-ment yield is highly sensitive to subbasin size and slope discretization. Baseflow is an important component of the total discharge within the study area that contributes more than the surface runoff. There is a good agreement between the measured and simulated flows and sediment yields with higher values of coefficients of determination and Nash Sutcliffe efficiency. The an-nual average measured sediment yield in Anjeni watershed was 24.6 tonnes/ha. The annual aver-age simulated sediment yield was 27.8 and 29.5 tonnes/ha for calibration and validation periods, respectively. The SWAT model indicated that 18.5 % of the Lake Tana Basin is erosion potential areas. Whereas the MCE result indicated that 25.5 % of the basin are erosion potential areas. The calibrated model can be used for further analysis of the effect of climate and land use change as well as other different management scenarios on streamflows and soil erosion. The result of the study could help different stakeholders to plan and implement appropriate soil and water conser-vation strategies. / QC 20101123
214

WATER RESOURCES MANAGEMENT SOLUTIONS FOR EAST AFRICA: INCREASING AVAILABILITY AND UTILIZATION OF DATA FOR DECISION-MAKING

Victoria M Garibay (12890987) 27 June 2022 (has links)
<p>  </p> <p>The management of water resources in East Africa is inherently challenged by rainfall variability and the uneven spatial distribution of freshwater resources. In addition to these issues, meteorological and water data collection has been inconsistent over the past decades, and unclearly defined purposes or end goals for collected data have left many datasets ineffectively curated. In light of the data intensiveness of current modelling and planning methods, data scarcity and inaccessibility have become substantial impediments to informed decision-making. Among the outputs of this research are 1) a revised technique for evaluating bias correction performance on reanalysis data for use in regions where precipitation data is temporally discontinuous which can potentially be applied to other types of climate data as well, 2) a new methodology for quantifying qualitative information contained in legislation and official documents and websites for the assessment of relationships between documented meteorological and water data policies and resulting outcomes in terms of data availability and accessibility, and 3) a fresh look at data needs and the value data holds with respect to water resources decision-making and management in the region.</p>
215

ASSESSMENT OF VARIABILITY OF LAND USE IMPACTS ON WATER QUALITY CONTAMINANTS

Johann Alexander Vera (14103150), Bernard A. Engel (5644601) 10 December 2022 (has links)
<p> The hydrological cycle is affected by land use variability. Land use spatial and temporal variability has the power to alter watershed runoff, water resource quantity and quality, ecosystems, and environmental sustainability. In recent decades, agriculture lands, pastures, plantations, and urban areas have increased, resulting in significant increases in energy, water, and fertilizer usage, as well as significant biodiversity losses. </p>
216

Palynological studies and Holocene ecosystem dynamics in north western Khyber Pakhtunkhwa Province of Pakistan in the Hindu Kush Himalayan region / Trends of pollen grain size variation in C3 and C4 Poaceae species using pollen morphology for future assessment of grassland ecosystem dynamics / Vegetation and pollen along a 200 km transect in Khyber Pakhtunkhwa Province, north western Pakistan / Vegetation and climate dynamics in Khyber Pakhtunkhwa, north-western Pakistan, inferred from the Kabal Swat pollen record during the last 3300 years

Farooq, Jan 30 April 2015 (has links)
Khyber Pakhtunkhwa (31 ° 49'N, 70 ° 55'E bis 35 ° 50'N, 71 ° 47'E) liegt im Nordwesten Pakistans im Süden Asiens. Das Hindukusch-Gebirge in Afghanistan liegt im Westen, dem indischen Himalaya im Nordosten und die Karakorum Berge südlich vom tibetischen Hochland auf der Nordseite. Diese Arbeit besteht überwiegend aus drei separaten Studien entlang eines 200 km langen Transekts mit einem Höhengradienten ausgehend von den Sedimentbecken im Peshawar Tal (275 m ü.M.) bis hinauf zu den Malam Jabba Hills im Swat-Tal (2600 m ü.M.). Die erste Studie, die auf einer Datengrundlage von 160 Poaceae Arten beruht, zeigt Trends, dass polyploide C3- und C4-Poaceae-Arten größere Pollenkkörner als die jeweiligen diploiden Arten haben. In diesem Datensatz haben alle C4-Arten größere Pollenkörner als die C3-Arten. Ob Grassländer von C3 oder C4 Arten dominiert werden kann in verschiedenen Regionen und Lebensräumen durch die Untersuchung der Muster des Trends von zu- oder abnehmenden Pollenkorngrößen ermittelt werden. In unserem Datensatz ist Polyploidie bei C4-Gräsern häufiger als bei den C3 Arten. Die verwendete Methode kann auf Poaceae-Pollenkörner in Umweltarchiven angewendet werden, um das Klima der Vergangenheit zu rekonstruieren und die Dynamik der früheren Graslandökosysteme zu bewerten. Dieser Ansatz wird nicht nur bei laufenden paläoökologischen Studien helfen aufzuklären, wie die Änderungen der Vegetations-zusammensetzung und die Veränderungen in Biomen vergangener Graslandökosysteme zu entschlüsseln sind, sondern auch nützliche Erkenntnisse für die Vorhersage zukünftiger Entwicklungen ermöglichen. Die zweite Studie befasst sich mit modernen Pollenspektren aus Oberflächenproben und ihre Beziehung zu der umgebenden Vegetation, die nützliche Daten für die Interpretation von holozänen Pollenprofilen bietet. Dabei konnten entlang eines 200 km langen Höhengradienten vier verschiedene Höhenstufen unterschieden werden, wo die dominierenden Pflanzenfamilien, Poaceae, Asteraceae, Cyperaceae, Verbenaceae, Acanthaceae und Euphorbiaceae eine signifikante Korrelation mit dem gefunden Pollenniederschlag hatten, während sich bei anderen Familien, den Boraginaceae, Saxifragaceae, Apiaceae, Balsaminaceae und Rubiaceae große Unterschiede zu der zugehörigen Vegetationszusammensetzung ergaben. Für die Kalibrierung und Interpretation fossiler Pollendaten sollte also immer auch die aktuellen Beziehungen von Pollenniederschlag und Vegetationsdaten zumindest auf der Familienebene berücksichtigt werden. Die dritte Studie befasst sich mit einem Pollenprofil aus der Kabal Swat-Region, welches eine detaillierte Geschichte der Vegetation und des Klimas des Hindukuschs der letzten 3300 Jahre, also dem späten Holozäns enthält. Von 3300 bis 2400 cal BP, war eine subtropische semiaride krautige Vegetation hauptsächlich durch Cyperaceae- und Poaceae-Arten vertreten. Sie wurde ersetzt von gemischten Nadelwäldern mit Taxus, Pinus, sowie Juglans, Poaceae und Cyperaceae während der Zeit von 2400 bis 900 cal BP, was auf eine vergleichsweise moderate Klimaschwankung während des späten Holozäns weist. Der Rückgang der Poaceae von 2400 bis1500 cal BP und eine erneute Zunahme von 1500 bis 1200 cal BP Jahre zeigen, dass das Kabal Swat nass-kühlere und trocken-wärmere Phasen durchmachte. Nadelbäume in den gemischten Nadelwäldern treten heute bei größeren Höhe im alpinen Bereich auf. Weitere hochauflösende holozäne Pollenprofile des Hindukusch sind notwendig, um einen ausführlicheren Vergleich zu anderen süd- und zentralasiatischen Paläo-Archiven zu ermöglichen, die auch ein detaillierteres und anwendbares Wissen für Management und Naturschutzfragen ergeben.
217

Estabelecimento de metodologia para a conservação e recuperação de pequenas bacias hidrográficas do Semiárido. / Establishment of a methodology for the conservation and restoration of small hydrographic basins of the Brazilian Semi-arid.

ALCÂNTARA, Hugo Morais de. 05 September 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-05T19:13:02Z No. of bitstreams: 1 HUGO MORAIS DE ALCÂNTARA - TESE PPGRN 2013..pdf: 10749707 bytes, checksum: 042c63fe46b2820168cc4a2b33b2f966 (MD5) / Made available in DSpace on 2018-09-05T19:13:02Z (GMT). No. of bitstreams: 1 HUGO MORAIS DE ALCÂNTARA - TESE PPGRN 2013..pdf: 10749707 bytes, checksum: 042c63fe46b2820168cc4a2b33b2f966 (MD5) Previous issue date: 2013-08-29 / Em regiões tropicais, como o semiárido brasileiro, a redução de áreas de florestas por meio da extração de lenha, da agricultura e pecuária de subsistência, associada à variabilidade espacial e temporal dos regimes climático e hidrológico, têm contribuído significativamente para a degradação ambiental de extensas áreas. Estudos em bacias experimentais têm evidenciado o papel da cobertura vegetal sobre a redução da erosão como um dos principais fatores para a conservação de pequenas bacias rurais, mas em geral não consideram as relações do homem com o ambiente. Esta tese tem como o principal problema de pesquisa a conservação e/ou recuperação ambiental de pequenas bacias hidrográficas rurais na região do semiárido brasileiro. A hipótese que norteia o trabalho é que uma metodologia que considere cenários futuros de uso e ocupação do solo e as relações do homem com o meio ambiente resultará em uma maior possibilidade de implementação das estratégias conservacionistas. O objetivo deste trabalho é a proposição de metodologia para a seleção de estratégias de conservação e/ou recuperação de pequenas bacias hidrográficas do semiárido, na perspectiva dos recursos hídricos, através de modelagem ambiental, considerando a aceitabilidade social dessas estratégias pelas comunidades rurais que ocupam as bacias. A metodologia proposta enfatiza a necessidade de uma caracterização ambiental considerando fatores climáticos, hidrológicos, políticos, econômicos e sociais, para embasar um planejamento conservacionista realista, viável e que esteja em sintonia com as necessidades dos produtores rurais. Advoga-se o uso de entrevistas e reuniões com os produtores e de modelos de simulação ambiental como ferramental. Os modelos podem contribuir na localização de áreas críticas e fornecer subsídios para a identificação de potenciais estratégias para a redução dos processos erosivos em diferentes escalas espaciais. A metodologia foi aplicada em uma pequena bacia hidrográfica do semiárido do estado da Paraíba. Estratégias candidatas de conservação e recuperação da bacia foram identificadas por meio de reuniões com grupos focais de produtores rurais. O modelo hidrossedimentológico SWAT foi usado com o objetivo de estimar a produção de sedimentos e a lâmina escoada. Foram simulados, com dados climáticos do período de 1998 a 2012, quatro cenários de uso e ocupação do solo montados de acordo com o levantamento de opiniões dos produtores rurais, tendo sido contempladas as estratégias com maior aceitabilidade social. O envolvimento da sociedade nas discussões e negociações ajuda a incorporar, no planejamento de uso dos recursos naturais, aspectos ambientais, culturais e sociais. Os resultados das simulações indicam uma estimativa anual da produção de sedimentos para o cenário atual de uso e ocupação do solo superando de 1,7 a 2,7 vezes os limites de tolerância de perda de solo estabelecidos em nível mundial, porém as estratégias de alterações de uso e ocupação do solo podem reduzir quase totalmente a produção anual de sedimentos e aumentar a produção de água na bacia em até 55,0%. Uma vantagem da metodologia proposta é que, através de uma lista de indicadores socioeconômicos e ambientais, a comunidade pode participar ativamente da pesquisa de campo, tornando-se parte integrante do gerenciamento dos recursos naturais. / In tropical regions, such as the Brazilian semiarid region, the reduction of forest areas by extracting firewood, subsistence agriculture and livestock, associated with spatial and temporal variability of the climatic and hydrological regimes, have significantly contributed to environmental degradation of extensive areas. Research in experimental basins have shown the role of vegetation on erosion reduction as a major factor for the conservation of small rural basins, but generally do not consider the relationship between human society and the environment. This thesis has as its main research problem the conservation and/or environmental remediation of small rural watersheds in the semiarid region of Brazil. The hypothesis that guides the work is that a methodology that considers future scenarios of land use and occupation and the communities’ relationships with the environment will result in a greater possibility of implementation of conservation strategies. The objective of this work is to propose a methodology for the selection of strategies for conservation and/or restoration of small watersheds, from a water resources viewpoint through environmental modeling, considering the social acceptability of these strategies by rural communities that occupy the basins. The methodology emphasizes the need for environmental characterization considering climatic, hydrological, political, economic and social aspects, to support a realistic and feasible conservation planning, considering the farmers’ needs. It advocates the use of interviews and meetings with farmers and environmental simulation models as methodological tools. Models can help in locating critical areas and provide tools for identifying potential strategies to reduce erosion at different spatial scales. The methodology was applied in a small watershed in semiarid region of the State of Paraíba. Candidate strategies for the conservation and restoration of the basin were identified through meetings with focus groups of farmers. The SWAT hydrological model was used to estimate sediment production and runoff. Four scenarios of land use and occupation were simulated using climate data for the period 1998-2012. The scenarios were selected according to the opinions of farmers, having been contemplated strategies with greater social acceptability. Society involvement in the discussions and negotiations helps to incorporate environmental, cultural and social aspects in the planning process. Simulation results show an estimate of annual sediment yield at the current scenario of the use and occupation of land exceeding 1.7 to 2.7 times the tolerance limits established for soil loss worldwide, but the restoration strategies can reduce almost totally the annual sediment yield and increase water production in the basin up to 55.0%. An advantage of the proposed methodology is that through a list of socioeconomic and environmental indicators, the community can actively participate in the field research, becoming an integral part of natural resource management.
218

Nonpoint Source Pollutant Modeling in Small Agricultural Watersheds with the Water Erosion Prediction Project

Ryan McGehee (14054223) 04 November 2022 (has links)
<p>Current watershed-scale, nonpoint source (NPS) pollution models do not represent the processes and impacts of agricultural best management practices (BMP) on water quality with sufficient detail. To begin addressing this gap, a novel process-based, watershed-scale, water quality model (WEPP-WQ) was developed based on the Water Erosion Prediction Project (WEPP) and the Soil and Water Assessment Tool (SWAT) models. The proposed model was validated at both hillslope and watershed scales for runoff, sediment, and both soluble and particulate forms of nitrogen and phosphorus. WEPP-WQ is now one of only two models which simulates BMP impacts on water quality in ‘high’ detail, and it is the only one not based on USLE sediment predictions. Model validations indicated that particulate nutrient predictions were better than soluble nutrient predictions for both nitrogen and phosphorus. Predictions of uniform conditions outperformed nonuniform conditions, and calibrated model simulations performed better than uncalibrated model simulations. Applications of these kinds of models in real-world, historical simulations are often limited by a lack of field-scale agricultural management inputs. Therefore, a prototype tool was developed to derive management inputs for hydrologic models from remotely sensed imagery at field-scale resolution. At present, only predictions of crop, cover crop, and tillage practice inference are supported and were validated at annual and average annual time intervals based on data availability for the various management endpoints. Extraction model training and validation were substantially limited by relatively small field areas in the observed management dataset. Both of these efforts contribute to computational modeling research and applications pertaining to agricultural systems and their impacts on the environment.</p>
219

Interaktionskvalitet - hur mäts det?

Friberg, Annika January 2009 (has links)
Den tekniska utvecklingen har lett till att massiva mängder av information sänds, i högahastigheter. Detta flöde måste vi lära oss att hantera. För att maximera nyttan av de nyateknikerna och undkomma de problem som detta enorma informationsflöde bär med sig, börinteraktionskvalitet studeras. Vi måste anpassa gränssnitt efter användaren eftersom denneinte har möjlighet att anpassa sig till, och sortera i för stora informationsmängder. Vi måsteutveckla system som gör människan mer effektiv vid användande av gränssnitt.För att anpassa gränssnitten efter användarens behov och begränsningar krävs kunskaperom den mänskliga kognitionen. När kognitiv belastning studeras är det viktigt att en såflexibel, lättillgänglig och icke-påträngande teknik som möjligt används för att få objektivamätresultat, samtidigt som pålitligheten är av största vikt. För att kunna designa gränssnittmed hög interaktionskvalitet krävs en teknik att utvärdera dessa. Målet med uppsatsen är attfastställa en mätmetod väl lämpad för mätning av interaktionskvalitet.För mätning av interaktionskvalitet rekommenderas en kombinering av subjektiva ochfysiologiska mätmetoder, detta innefattar en kombination av Functional near-infraredspecroscopy; en fysiologisk mätmetod som mäter hjärnaktiviteten med hjälp av ljuskällor ochdetektorer som fästs på frontalloben, Electrodermal activity; en fysiologisk mätmetod sommäter hjärnaktiviteten med hjälp av elektroder som fästs över skalpen och NASA task loadindex; en subjektiv, multidimensionell mätmetod som bygger på kortsortering och mäteruppfattad kognitiv belastning i en sammanhängande skala. Mätning med hjälp av dessametoder kan resultera i en ökad interaktionskvalitet i interaktiva, fysiska och digitalagränssnitt. En uppskattning av interaktionskvalitet kan bidra till att fel vid interaktionminimeras, vilket innebär en förbättring av användares upplevelse vid interaktion. / Technical developments have led to the broadcasting of massive amounts of information, athigh velocities. We must learn to handle this flow. To maximize the benefits of newtechnologies and avoid the problems that this immense information flow brings, interactionquality should be studied. We must adjust interfaces to the user because the user does nothave the ability to adapt and sort overly large amounts of information. We must developsystems that make the human more efficient when using interfaces.To adjust the interfaces to the user needs and limitations, knowledge about humancognitive processes is required. When cognitive workload is studied it is important that aflexible, easily accessed and non assertive technique is used to get unbiased results. At thesame time reliability is of great importance. To design interfaces with high interaction quality,a technique to evaluate these is required. The aim of this paper is to establish a method that iswell suited for measurement of interaction quality.When measuring interaction quality, a combination of subjective and physiologicalmethods is recommended. This comprises a combination of Functional near-infraredspectroscopy; a physiological measurement which measures brain activity using light sourcesand detectors placed on the frontal lobe, Electrodermal activity; a physiological measurementwhich measures brain activity using electrodes placed over the scalp and NASA task loadindex; a subjective, multidimensional measurement based on card sorting and measures theindividual perceived cognitive workload on a continuum scale. Measuring with these methodscan result in an increase in interaction quality in interactive, physical and digital interfaces.An estimation of interaction quality can contribute to eliminate interaction errors, thusimproving the user’s interaction experience.

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