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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.
131

Improvements to Flood Detection and Monitoring Through Satellite Autonomy, Sensor Webs and Hydrological Modeling

Ip, Filipe January 2006 (has links)
This dissertation is put together from a set of three journal papers. The first paper describes how satellite imagery and spacecraft autonomy are used to advance the field of near real-time detection, monitoring, and rapid response to flooding. The second paper describes the ground instrumentation of an artificial water recharge basin field site close to Tucson with a network of inter-connected sensors to study the transient process of repeated flooding in real-time, and the third paper describes an effort to link together multiple ground-based and space-based remote sensing assets to an integrated and coordinated monitoring system for floods. Collectively, the three papers describe new breakthroughs in the field of flood detection and monitoring through the use of satellite onboard automation and Sensorweb networks.
132

Study of the Spatiotemporal Characteristics of Meltwater Contribution to the Total Runoff in the Upper Changjiang River Basin

Fang, Yuan-Hao, Zhang, Xingnan, Niu, Guo-Yue, Zeng, Wenzhi, Zhu, Jinfeng, Zhang, Tao 25 February 2017 (has links)
Melt runoff (MR) contributes significantly to the total runoff in many river basins. Knowledge of the meltwater contribution (MCR, defined as the ratio of MR to the total runoff) to the total runoff benefits water resource management and flood control. A process-based land surface model, Noah-MP, was used to investigate the spatiotemporal characteristics of MR and MCR in the Upper Changjiang River (as known as Yangtze River) Basin (UCRB) located in southwestern China. The model was first calibrated and validated using snow cover fraction (SCF), runoff, and evapotranspiration (ET) data. The calibrated model was then used to perform two numerical experiments from 1981 to 2010: control experiment that considers MR and an alternative experiment that MR is removed. The difference between two experiments was used to quantify MR and MCR. The results show that in the entire UCRB, MCR was approximately 2.0% during the study period; however, MCR exhibited notable spatiotemporal variability. Four sub-regions over the Qinghai-Tibet Plateau (QTP) showed significant annual MCR ranging from 3.9% to 6.0%, while two sub-regions in the low plain regions showed negligible annual MCR. The spatial distribution of MCR was generally consistent with the distribution of glaciers and elevation distribution. Mann-Kendall (M-K) tests of the long-term annual MCR indicated that the four sub-regions in QTP exhibited increasing trends ranging from 0.01%/year to 0.21%/year during the study period but only one displayed statistically significant trend. No trends were found for the peak time (PT) of MR and MCR, in contrast, advancing trend were observed for the center time (CT) of MR, ranging from 0.01 months/year to 0.02 months/year. These trends are related to the changes of air temperature and precipitation in the study area.
133

Assessing the value of stable water isotopes in hydrologic modeling: a dual-isotope approach

Holmes, Tegan 13 September 2016 (has links)
This thesis presents the development of a dual-isotope simulation in a hydrological model, and its application to the lower Nelson River basin. The purpose of this study is to find if the simulation of stable water isotopes aids in hydrological simulation, and if a dual-isotope simulation is an improvement over a single-isotope simulation. The isoWATFLOOD model was enhanced to include δ2H and improve physical representativeness. The model was calibrated using various isotope and flow simulation error functions. Internal hydrologic storages and fluxes were verified by comparing simulated isotope values to observed isotope data. Adding isotope error to the calibration resulted in small but consistent improvements to the physical basis of calibrated parameter values. Isotope simulation error was found to be the best predictor of streamflow simulation performance beyond the calibration period. The dual-isotope simulation identified a number of model limitations and potential improvements from the verification of internal hydrologic storages. / October 2016
134

Optimalizace digitální podoby říční sítě a její dopad na vodohospodářský management povodí / Optimization of digital river network and its impact on catchment water management

Hošek, Zdeněk January 2016 (has links)
Digital river network dataset is an important source of information in any aspect of water management decision making. It is also a base for modelling or scientific research in many different fields. Development of the dataset in the Czech Republic had been fragmented in a past and as a result three different datasets have been developed that cover the whole of the state's territory. The datasets contain different geometries, different and often conflicting attributes and serve different purposes. Today the time has come that water management decision makers have realised that the situation is no longer sustainable and make effort to merge the datasets into one. The task brings in several technical issues and a potential for severe legal consequences. The aim of this study is to develop a methodological approach to merging the existing datasets into one. This methodological approach to decision which of the conflicting or different attributes should be adopted is based on assumption that the existing datasets will be merged into one consisting the best of all. Comparison of features in the existing dataset will inevitably lead to many conflicts when it will be necessary to decide which of the considered features should be adopted to the resulting dataset. The study considers the main purposes which...
135

Projevy a dopady hydrologického sucha v povodí Rakovnického potoka / Signs and impacts of hydrological drought in the Rakovnicky stream basin

Maroušková, Kateřina January 2016 (has links)
This thesis deals with the signs and impacts of the hydrological drought in the Rakovnicky stream basin. Its aim is to evaluate trends of the selected hydroclimatic variables, to analyze drought periods and land cover changes as one of the factors influencing a runoff regime in the catchment. The main methods used for the long-term and seasonal trends are Man-Kendall test, IHA analysis, flow duration curves and mass curves. Dry periods are evaluated based on Streamflow drought index (SDI), Low Flow index and runoff Q95 exeedance. Land use changes are analyzed using historical maps and index of change. Basic indices of ecological stability are calculated. According to the results the frequency and intensity of the hydrological drought in the Rakovnicky stream basin is increasing. Although the amount of a rainfall is consistent, its distribution throughout the year is changing. In addition the constantly increasing temperature and land use changes cause a significant runoff decreasing. To improve a water retention capacity in the cathment, it would be convenient to apply adaptation measures in the river channels and floodplains. Key words: rainfall, runoff, drought, ecological status, Rakovnicky stream
136

Artificial neural network for water resource prediction in scientific workflows

14 January 2014 (has links)
M.Ing. (Electrical and Electronic Engineering Science) / Scientific workflows (SWFs) and artificial neural networks (ANNs) have attracted the attention of researchers in many fields and have been used to solve a variety of problems. Examples of these are (a) the use of scientific workflows for the sensor web in the hydrology domain and (b), the use of ANNs for the prediction of a number of water resource variables such as rainfall, flow, water level and various other water quality variables. ANNs have proved to be a powerful tool for prediction when compared with statistical methods. The aims of this research are to develop ANNs that act as predictive models for water resources and to deploy these models as predictive tools in a scientific workflow environment. While there are guidelines in the literature relating to the factors affecting network performance, there is no standard approach that is universally accepted for determining the optimum architecture of a neural network for a given problem. The parameters of a neural network and for the learning algorithm have a major effect on the performance of the neural network. We consider various recurrent and feed-forward neural network architectures for predicting changes in the water levels of dams. We explore various' hidden layer dimensions in learning the characteristics of the training data using the back propagation learning algorithm. Trained networks are deployed as predictive model in a scientific workflows environment called VisTrails. ': We review and discuss the use of SWFs and ANNs in the hydrology domain with emphasis on the development of neural network architecture that will give the best predictions for water resources. A number of architectures are employed to examine the best accurate predictive network for historical rainfall data. The findings of training experiments are promising in terms of the use of ANNs as a water resources predictive tool. Experimental results showed how the architecture of a neural network impacts on its predictive performance. This study shows that the number of hidden nodes is important factor for the improvement of the quality of the predictions.
137

Sezónní pravděpodobnostní hydrologické předpovědi / Seasonal probabilistic hydrological forecasting

Šípek, Václav January 2014 (has links)
Seasonal hydrological forecasts represent a very current topic, especially in the context of extreme hydrological events that have taken place at the end of the 20th and beginning of the 21st century. These events are represented by large scale floods and long lasting periods of drought. This has led to a need for the effective water management strategies. These management strategies have to be able to efficiently distribute water resources both in the space and time. Seasonal hydrological forecasting systems constitute an essential part of water management strategies, as they enable the runoff estimation in a sufficient advance. This thesis deals with the seasonal hydrological forecasting system with a one month lead. The aim of this study is to apply three forecasting methods using an experimental watershed in the Czech Republic. The first method is represented by the reference climatology approach, the latter by the well-tested Ensemble Streamflow Prediction system (ESP), and the last by its newly proposed modification. This modification (modified ESP - mESP) is based on the restriction of input data established on their relations to the large scale climatological variables and patters. The first part of the thesis is focused on the investigation of possible relations among hydrometeorological...
138

Hydrological risk transfer planning under the drought \"severity-duration-frequency\" approach as a climate change impact mitigation strategy / Planejamento da transferência de riscos hidrológicos sob a abordagem \"severidade-duração-frequência\" da seca como uma estratégia de mitigação dos impactos das mudanças climáticas

Guzman Arias, Diego Alejandro 26 March 2018 (has links)
Climate change and increasing water demands prioritize the need to implement planning strategies for urban water security in the long and medium term. However, risk planning requires robust and timely financial support during and after the disaster. Therefore, risk transfer tools, such as insurance, have emerged as an effective strategy to ensure financial resilience and as an element that could encourage the implementation of hydrological risk reduction mechanisms. Among the main insurance design problems are the lack of information on the real drought impacts and climate uncertainty, which may incur adverse selection and/or moral hazards among the most common drawbacks in insurance practice. Currently, most of the income from water utility companies is based on water resources management, therefore during prolonged drought periods these economies can be strongly affected, despite having robust storage schemes as support. Thus, this thesis proposes an insurance plan for the water utility company of the State of Sao Paulo (SABESP) to deal with revenue reductions during long drought periods. The methodology is implemented on the MTRH-SHS model, developed under ex-ante damage cost calculation through the risk-based approach. The synthetic (\'what-if\') approach uses a \"set of change drivers\" to estimate the optimal premium through a multiyear insurance contract (MYI). The methodology integrates the hydrological simulation procedures under radiative climate forcing scenarios RCP 4.5 and 8.5, from the regional climate model outputs Eta-HadGEM and Eta-MIROC5, with time horizons of 2007-2040, 2041-2070, and 2071-2099, linked to the Water Evaluation and Planning system (WEAP) hydrologic model and under stationary and non-stationary water supply demand assumptions. The model framework is applied to the Cantareira Water Supply System for the Sao Paulo Metropolitan Region, Brazil, with severe vulnerability to droughts. As a result, the evaluated indexes showed that multi-year contracts with drought coverage higher than 240 days offer better financial performance than contracts with wider coverages. Moreover, this MYI adopted in the installed storage residual risk generates both a higher level of solvency for the insurance fund in the long term and annual average premiums closer to the expected revenue reductions by scenario. Finally, the approach can help the systematic evaluation of moral hazards and adverse selection. In the first case, the progressive evaluation must generate useful information to change or maintain the behavior of both the insured and insurers considering future risks related to climate change. In the second case, the multi-scenario valuation can help the insurer to set price thresholds, offering risk differential cover options in the premium value. / As mudanças climáticas e o incremento na demanda de água priorizam a necessidade de implementar estratégias de planejamento para a segurança hídrica urbana no longo e mediano prazo. No entanto, o planejamento dos riscos exige um suporte financeiro robusto e oportuno durante e após do desastre. Portanto, as ferramentas de transferência de risco, como os seguros, emergem como uma estratégia efetiva para garantir a resiliência financeira e como um elemento que poderia incentivar a implementação de mecanismos de redução do risco hidrológico. Entre os principais problemas no planejamento de seguros, estão a falta de informações sobre os impactos reais das secas e a incerteza climática, que podem levar a seleção adversa e/ou perigo moral como as problemáticas mais comuns na prática dos seguros. Atualmente, a maior parte da renda das empresas de serviços de água é baseada na gestão do recurso hídrico; portanto, durante períodos prolongados de seca, essas economias podem ser fortemente afetadas, apesar de ter sistemas de armazenamento robustos como suporte. Assim, esta tese propõe um plano de seguro para a empresa de serviços de água do Estado de São Paulo (SABESP), para enfrentar as reduções de receita durante longos períodos de seca. A metodologia é implementada no modelo MTRH-SHS, desenvolvido no cálculo \"ex-ante\" de custos de dano, através da abordagem baseada em risco. A abordagem sintética (\"what-if\"), usa um \"conjunto de drivers de mudança\" para estimar o prêmio ótimo através de um contrato de seguro plurianual (SPA). A metodologia integra os procedimentos de simulação hidrológica, sob cenários de forçamento climático radiativo RCP 4.5 e 8.5, do modelo de clima regional Eta-HadGEM e Eta-MIROC5, com horizontes temporais de 2007-2040, 2041-2070 e 2071-2099, vinculados ao modelo hidrológico do sistema de avaliação e planejamento da água (WEAP) e sob pressupostos de demanda como abastecimento de água estacionária e não estacionária. A estrutura do modelo é aplicada ao Sistema de Abastecimento de Água de Cantareira na Região Metropolitana de São Paulo, Brasil, região com alta vulnerabilidade às secas. Como resultado, os índices de rendimento do seguro avaliados mostraram que os contratos plurianuais com cobertura para secas superiores a 240 dias, oferecem melhor desempenho financeiro do que os contratos com coberturas mais amplas. Além, o SPA adotado para o risco residual do armazenamento instalado, gera um nível mais alto de solvência para o fundo de seguros no longo prazo com prêmios médios anuais mais próximos das reduções de receita esperadas por cenário. Finalmente, a abordagem pode ajudar na avaliação sistemática do risco moral e na seleção adversa. No primeiro caso, a avaliação progressiva deve gerar informações úteis para mudar ou manter o comportamento de segurados e seguradoras considerando riscos futuros relacionados à mudança climática. No segundo caso, a valoração de múltiplos cenários pode ajudar a estabelecer limiares de preços, oferecendo opções de cobertura diferencial de risco no valor prêmio de seguro.
139

Simulação hidrológica de bacias amazônicas utilizando o modelo de Capacidade de Infiltração Variável (VIC) / Hydrologic simulation of Amazon basins using the Variable Infiltration Capacity model (VIC)

Victoria, Daniel de Castro 22 February 2010 (has links)
Com 6 milhões de km2, a bacia Amazônica é o maior sistema hidrográfico do mundo, com descarga estimada de 209.000 m3 s-1, e a maior extensão contínua de floresta tropical. Porém, esta região é alvo de constantes ameaças, seja das pressões por desmatamento, ou por alterações climáticas. Neste contexto, compreender o funcionamento do sistema é essencial, seja para auxiliar na tomada de decisões ou estudos de cenários futuros. Este trabalho teve como objetivo avaliar e adaptar o modelo hidrológico de grandes bacias Variable Infiltration Capacity Model (VIC v.4.0.5), para as condições tropicais. Foram utilizados dados de descarga, precipitação, temperatura e velocidade do vento, e informações sobre tipo de solo e cobertura vegetal, para simular o ciclo hidrológico em 6 grandes bacias situadas na Amazônia: Santo Antônio do Içá, Japurá, Juruá, Negro, Madeira e Purus. O modelo foi calibrado a partir das descargas mensais, de 1980 a 1990, e seu funcionamento foi verificado para o período de 1990 a 2006. Não foi possível simular o ciclo hidrológico para as bacias com grande contribuição dos Andes, Santo A. Içá e Japurá, uma vez que a estimativa de precipitação nestas regiões é subestimada. Nas outras bacias, o modelo foi capaz de simular corretamente as vazões dos rios, apesar de apresentar problemas na estimativa da evapotranspiração (ET). Foram constatados problemas na partição da ET em seus componentes, transpiração da vegetação e evaporação da água interceptada. Uma possível correção foi avaliada, resultando em uma distribuição mais correta da ET em seus componentes porém, tal modificação resultou em redução da ET média simulada. Uma nova versão do modelo (v.4.1) acaba de ser lançada. Dentre as melhorias, destacam-se modificações na maneira como a ET é calculada, que visa corrigir os problemas aqui relatados. No entanto, tal versão ainda não foi avaliada nas condições tropicais / The Amazon river basin is the largest fluvial system in the world, discharging 209,000 m3 s-1 to the ocean. It also sustains the largest continuous tropical forest system. However, the region is under constant pressure from deforestation and climate change. For such reasons, its crucial to understand how the hydrological cycle functions. Such tools can be used for evaluation of future scenarios and guide decision making. The Variable infiltration Capacity Model (VIC) was evaluated and adapted to tropical conditions. Temperature, precipitation, wind speed, soil type and land cover maps were used to simulate the hydrological cycle in 2 sub-basins inside the Amazon: Santo Antônio do Içá, Japurá, Juruá, Negro, Madeira e Purus, covering the period from 1980 to 2006. The simulation was not possible for basins with large drainage area located in the Andes (Santo A. Içá and Japurá), due to underestimation of the precipitation. For the other basins, simulated discharge agreed with observed records, even though evapotranspiration (ET) estimates showed some problems. The ET partitioning in its components, transpiration and canopy evaporation, showed severe discrepancies. A correction was applied to the model, fixing the partitioning problem but it resulted in reduction of estimate ET. A new version of the model (v.4.1) has just been released, with changes in the way ET is estimated. However, this new version has not yet been tested in the Amazon
140

Avaliação dos impactos hídricos da monocultura de eucalipto cultivado no trecho paulista da Bacia Hidrografica do rio Paraíba do Sul (BRASIL) / Assessment of water impacts of eucalyptus monoculture in the portion of the Basin of the Paraíba do Sul River in São Paulo (BRAZIL)

Tadeu, Natalia Dias 13 March 2014 (has links)
Modificações da cobertura natural dos solos podem ocasionar alterações no ciclo hidrológico, que por sua vez podem impactar a disponibilidade de água. Na Bacia Hidrográfica do Rio Paraíba do Sul (BHPS) vem ocorrendo uma substituição de coberturas vegetais em função da expansão de monoculturas de eucalipto. O objetivo desta pesquisa foi verificar os impactos de ordem hidrológica sobre a disponibilidade hídrica (quali e quantitativa) no trecho paulista da BHPS, em decorrência da implantação da atividade de silvicultura de eucalipto para produção de celulose. Para isso, foi utilizado o método de Pegada Hídrica (PH) para avaliar a alocação de água da produção de madeira de floresta nativa e de eucalipto, método que vem sendo aplicado pelo setor silvícola. Foram empregados também métodos de Balanço Hídrico Climatológico, Balanço Hídrico Geral e a abordagem de Serviços Ecossistêmicos para avaliar a relação entre a água e as principais coberturas vegetais da bacia (pastagem, floresta nativa e eucalipto), de forma a permitir uma análise ampliada e integrada do comportamento hidrológico da bacia. Ao analisar os métodos empregados, observou-se que a PH de produtos avalia apenas a eficiência do uso da água, o que pode mascarar altos consumos de água em função de maior produtividade por hectare. Isto porque se obteve menor valor de PH da madeira, em m³ por tonelada para o caso do eucalipto, e maior alocação total de água, em m³ por hectare por ano, em comparação à floresta nativa. Os resultados obtidos pela análise de Balanço Hídrico Climatológico para as principais coberturas vegetais mostraram que o eucalipto apresentou maior evapotranspiração e menor excedente hídrico. Já o Balanço Hídrico Geral, analisado mensalmente, permitiu visualizar que as coberturas vegetais influenciam o serviço de provisão de água e concorrem pelo uso de água com os demais usuários da bacia (naturais e antrópicos) em períodos de menor precipitação. Por fim, concluiu-se que são necessárias medições locais para determinação de volumes de escoamento (superficial e subterrâneo), infiltração, bem como do processo de lixiviação e perdas de solo para apontar de forma mais precisa os impactos hídricos da monocultura de eucalipto. / Modifications in the natural land cover can change the hydrological cycle, which might have an impact on water availability. In the river basin of the Paraíba do Sul river (RBPS), the natural vegetation has been being replaced due to the expansion of eucalyptus monocultures. This research assessed the impacts on water availability (both qualitative and quantitative), caused by eucalyptus forestry for pulp production in the RBPS part in Sao Paulo. The water footprint (WF) method was applied to assess the water used on the cellulose production of native forest and eucalyptus, given the use of this method by the industry. Also, the Climatic Water Balance, General Water Balance methods and the Ecosystem Services approach were used in order to perform an extended and integrated analysis of the hydrological behavior of the basin. By analyzing these methods, it was found that the products WF only assesses the efficiency in water use, which can mask high water consumption with higher productivity per hectare. This because a smaller value for wood WF was observed, in m³/ton for eucalyptus, and higher total water use, in m³ per hectare per year, compared to the native forest. The results observed by the Climatic Water Balance analysis for the main vegetation cover showed that the eucalyptus presented higher evapotranspiration and smaller water surplus. The General Water Balance, analyzed on a monthly basis, showed that the vegetation has an impact on the water provision service and competes for water with other users in the basin (natural and anthropic) in periods with less precipitation. Finally, it was concluded that local measurements are required to determine the runnof volumes (superficial and subsurface), infiltration, as well as the process of leaching and soil loss in order to have a more accurate assessment of the hydrological impacts of the eucalyptus monoculture.

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