Modeling within a Digital Watershed Context

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

Avaliação da conectividade de rios na Bacia do Alto Paraguai (BAP)

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Florestal, 2020.O Brasil aposta fortemente na produção de energia a partir de empreendimentos hidrelétricos, e há uma rápida expansão dos interesses na exploração dos recursos hídricos na região de planalto da Bacia do Alto Paraguai (BAP), onde se concentram as nascentes que abastecem esse sistema. As barragens alteram a vazão e fluxo dos rios, o que causa diversos impactos socioeconômicos e ambientais. Rios de fluxo livre são aqueles que mantêm trocas desobstruídas de energia, matéria e organismos pelo seu fluxo. Devido aos pulsos de inundação típicos da região, essa bacia é especialmente sensível aos efeitos da fragmentação e regulação hídrica. Este estudo apresenta a aplicação da avaliação de conectividade de rios proposta por Grill et al. (2019) na BAP, a fim de analisar o status de conectividade atual e estimar qual será o impacto da implantação dos projetos hidrelétricos que estão em fase de planejamento na conectividade num cenário futuro, e identificar as principais pressões atuantes nesse sistema. O método de avaliação utiliza seis indicadores de pressão para avaliar a conectividade das redes de drenagem: 1) grau de fragmentação, 2) grau de regulação, 3) densidade de rodovias, 4) uso e abstração de água, 5) infraestrutura urbana e 6) retenção de sedimentos. Com a construção das hidrelétricas planejadas, mais de 2.600 km de extensão de rios de fluxo livre seriam afetados. O rio Paraguai, que comanda a rede de drenagens da bacia, já é considerado um com conectividade prejudicada em diferentes níveis. Essa metodologia serve de embasamento para projetos de conservação e preservação de recursos hídricos e articulação com políticas públicas do setor elétrico.Brazil is strongly investing in the production of energy from hydroelectric power plants, and there is an increasing interest in the exploitation of water resources in the region of the Upper Paraguay Basin (BAP), where the headwaters that supply this system are located. Dams alter the river fragmentation and natural river flow, which causes several socioeconomic and environmental impacts. We define “free-flowing river” as rivers with unobstructed movement and exchange of energy, material, and organisms though its flow. Because of the typical flood pulses of the region, this basin is especially sensitive to the effects of fragmentation and water regulation. This study presents an application of the river connectivity assessment proposed by Grill et al. (2019) in BAP, in order to analyze the current connectivity status and estimate what would be the impact of the planned hydroelectric projects in the connectivity in a future scenario, and identify what are the main pressures acting in this system. This methodology uses six pressure indicators to assess the connectivity of drainage networks: 1) degree of fragmentation, 2) degree of regulation 3) road density, 4) water use and abstraction, 5) urban infrastructure and 6) sediment trapping. Considering the construction of the planned hydroelectric dams, more than 2,600 km of free-flowing rivers would be affected. The main river, Paraguay, which controls the drainage network of the basin, is already considered a regulated river, with its connectivity in jeopardize. This methodology serves as a basis for conservation and preservation of water resources projects and advocacy with public policies in the electricity sector

Modelling water discharge and nitrogen loads from drained agricultural land at field and watershed scale

This thesis examines water discharge and NO₃-N loads from drained agricultural land in southern Sweden by modelling at field and watershed scale. In the first stage of the work, the ability of DRAINMOD to simulate outflow in subsurface drains and that of DRAINMOD-N II to simulate NO₃-N loads in these drains was evaluated in field experiments. In addition, the ROSETTA pedotransfer model was used to estimate soil hydraulic properties required by DRAINMOD. In the second stage, DRAINMOD was integrated with Arc Hydro in a GIS framework (Arc Hydro-DRAINMOD) to simulate the hydrological response of an artificially drained watershed. DRAINMOD-N II and a temperature-dependent NO₃-N removal equation were also included in Arc Hydro-DRAINMOD to predict NO₃-N loading. Arc Hydro-DRAINMOD used a distributed modelling approach to aggregate the results of field-scale simulations, where the Arc Hydro data model described the drainage patterns in the watershed and connected the model simulations from fields through the stream network to the watershed outlet. GLUE methodology was applied to estimate uncertainties in the framework inputs. At field scale, monthly values of drain outflows simulated by DRAINMOD and NO₃-N loads simulated by DRAINMOD-N II showed good agreement with observed values. Good agreement was also found between observed and DRAINMOD-simulated drainage rates when ROSETTA-estimated Ks values were used as inputs in DRAINMOD. At watershed scale, temporal trend and magnitude of monthly measured discharge and NO₃-N loads were well predicted by Arc Hydro-DRAINMOD, which included uncertainty estimation using GLUE methodology. Sensitivity analysis showed that NO₃-N loads from the stream baseflow and N removal in the stream network processes had the most sensitive parameters. These results demonstrate the potential of DRAINMOD/DRAINMOD-N II and Arc Hydro-DRAINMOD for simulating hydrological and N processes in drained agricultural land at field and watershed scale. These models can contribute to improve water use efficiency in watersheds and to evaluate best management practices for preventing surface water and groundwater pollution

Flow and transport modeling in large river networks

textThe work presented in this dissertation discusses large scale flow and transport in river networks and investigates advantages and disadvantages of grid-based and vector-based river networks. This research uses the Mississippi River basin as a continental-case study and the Guadalupe and San Antonio rivers and Seine basin in France as regional-case studies. The first component of this research presents an extension of regional river flow modeling to the continental scale by using high resolution river data from NHDPlus dataset. This research discovers obstacles of flow computations for river a network with hundreds of thousands river segments in continental scales. An upscaling process is developed based on the vector-based river network to decrease the computational effort, and to reduce input file size. This research identifies drainage area as a key factor in the flow simulation, especially in a wet climate. The second component of this research presents an enhanced GIS framework for a steady-state riverine nitrogen transport modeling in the San Antonio and Guadalupe river network. Results show that the GIS framework can be applied to represent a spatial distribution of flow and total nitrogen in a large river network with thousands of connected river segment. However, time features of the GIS environment limit its applicability to large scale time-varied modeling. The third component shows a modeling regional flow and transport with consideration of stream-aquifer interactions at a regional scale at high resolution. The STICS- Eau-Dyssée combined system is implemented for entire seine basin to compute daily nitrate flux in the Seine grid river network. Results show that river-aquifer exchange has a significant impact on river flow and transport modeling in larger river networks.Civil, Architectural, and Environmental Engineerin

Metodologia de balanço hídrico e critérios de outorga em bacias hidrográficas com uso intenso de reservatórios de pequeno porte estudo de caso na bacia do Rio Quaraí

Os reservatórios se constituem numa das principais formas estabelecidas pelo homem de modificar o ciclo hidrológico ao armazenar água para sua utilização no futuro. Em algumas regiões do país este mecanismo é de fundamental importância para o atendimento das demandas consultivas, seja pelas condições adversas do clima, como é o caso do semiárido nordestino, como também em função da alta demanda de água requerida para o atendimento da irrigação, como ocorre em algumas áreas do Rio Grande do Sul. Este trabalho apresenta uma metodologia de balanço hídrico em rios e reservatórios de pequeno porte, cujo foco é o atendimento aos instrumentos da Política Nacional de Recursos Hídricos, como a outorga de direito de recursos hídricos e as políticas de planejamento. A metodologia está baseada na integração entre o modelo hidrológico chuva-vazão MGB-IPH como recurso para obtenção das séries afluentes de cada reservatório e trecho de rio do sistema hídrico. Associado ao modelo hidrológico, está a integração com os Sistemas de Informações Geográficas, que possuem a vantagem de obtenção das características físicas da bacia de forma automática, facilitando também a associação com os objetos que representam o sistema hídrico (i.e. demandas e reservatórios). O modelo de simulação realiza a contabilização do movimento de água através de um sistema de reservatórios e trechos de rio, cuja progressão de cálculo é realizada de montante para jusante. Como técnica de otimização, foi utilizado o algoritmo SCE-UA, baseado na teoria dos algoritmos evolucionários. A metodologia desenvolvida foi aplicada na Bacia do Rio Quaraí, caracterizada pelo intenso uso da água para o atendimento das demandas da irrigação, e também pelo estabelecimento de centenas de pequenas estruturas de reservação de água, destinadas ao abastecimento destas demandas. Os resultados indicaram que não há água suficiente para o atendimento das demandas da irrigação em 100% do tempo. Em média, apenas 75% do volume total de água requerido para o atendimento das demandas atuais poderia ser atendido, considerando o período simulado de 20 anos. Nos anos mais críticos pode ocorrer o esgotamento do curso principal do Quaraí e outros locais, decorrência das retiradas de água, além do efeito da reservação de água pelos açudes, pois admitiu-se a hipótese de não existirem descarregadores de fundo nessas estruturas. Como alternativas para a gestão da água na bacia, apontam-se a definição de critérios de outorga para retiradas e liberação de água em reservatórios, além de implementação de novas estruturas de reservação e regularização.Reservoirs are the most important form established by the man to modify the hydrological cycle to store water for use in the future. In some regions of Brazil this mechanism is crucial to meet the advisory needs, either by adverse weather conditions, such as the semi-arid northeast, but also due to the high demand of water required to meet the irrigation, as occurs in some areas of Rio Grande do Sul. This work presents a methodology of water balance in rivers and small reservoirs, whose focus is to achieve the goals of the instruments of the National Water Resources Policy, as the water rights and the planning policies. The methodology is based on the integration between the hydrological rainfall-runoff model MGB-IPH as a resource for obtaining streamflow series from upstreams of each reservoir and for all sub-watershed defined on the water system. Associated with the hydrological model is the integration with Geographic Information Systems, which have the advantage of obtaining the physical characteristics of the basin automatically, it also facilitates association with objects that represent the water system (i.e. demands and reservoirs). The simulation model performs accounting for the movement of water through a system of reservoirs and river stretches whose progression calculation is performed from upstream to downstream. As optimization technique, the SCE-UA algorithm, based on the theory of evolutionary algorithms was used. The procedure was applied in the Quaraí River Basin, characterized by intense use of water to meet the irrigation demands, and also by the establishment of hundreds of small structures reservation of water, destined to supply these demands. The results indicated that there is not water enough to meet the demands of irrigation at 100% of the time. On average, only 75% of the total volume of water required to meet the current demands could be met, considering the simulated period of 20 years. In the most critical years can occur exhaustion of the main course of the Quaraí and other sites, due to withdrawals plus the effect of the reservation by dams, it admitted the hypothesis that there are no releases in this structures. As alternatives to water management in the basin, point the definition of licensing criteria for withdrawals and releases in dams, as well as implementing new reservoir with regularization structures