Hydraulic and water quality model for a river network

A river network system consisting of branches and loops is sometimes complicated by downstream effects from tides, lakes, and because of this, management of water quality, sediment control, and floods, in such rivers is a difficult task. Development of tools to aid in the management decision-making process is an important area of research; ultimately resulting in more reliable results. River behavior can be modeled in detail (one-, two-, or three-dimensional models) with a digital computer using numerical methods. Usually the level of detail is determined by the size of the system. Large system models are restricted in size and detail due to the high cost and storage requirements of the computer. A model was developed to simulate the hydraulic behavior and water quality of a river network on a one-dimensional representation. The two complete St. Venant equations and the transport equation were solved by the finite difference method. The transport equation utilizes the advection, dispersion, and source and sink terms. The system of equations resulting from use of an implicit scheme was solved by a modified Gauss elimination procedure. The model can simulate biochemical oxygen demand, dissolved oxygen, or any other conservative substance. The basic equations are solved; thus, the simulation of other substances can be added to the model by including the mathematical description of the reaction processes in the source and sink terms of the transport equation. The hydraulic module of the model was adjusted and verified with data from the Jacui Delta, Brazil. Good agreement between the calculated results and the observed data resulted. The water quality model was tested under hypothetical conditions for the same Delta in order to demonstrate the utility of the mathematical model in making decisions at the management level. This model is a mathematical method that can be used in large systems of variable complexity to help in understanding their processes, controlling data measurements, and reaching sound management decisions

Otimização dos parâmetros de modelos hidrológicos

Este trabalho apresenta as técnicas de otimizaçao iterativas aplicada a modelos de simulação hidrológica. Para tanto utilizamos os modelos de propagação do tipo "descarga-descarga", descrevendo três desses modelos e utilizando num problema prático dois deles, otimizando seus parâmetros pelas técnicas apresentadas em detalhe. No trabalho é utilizado um programa de computador onde é descrita a sua estrutura e como deve ser usado

Drenagem urbana

O ciclo hidrológico sofre fortes alterações nas áreas urbanas devido, principalmente, à alteração da superfície e a canalização do escoamento, aumento de poluição devido à contaminação do ar, das superfícies urbanas e do material sólido disposto pela população. Esse processo apresenta grave impacto nos países em desenvolvimento, onde a urbanização e as obras de drenagem são realizadas de forma totalmente insustentável, abandonada pelos países desenvolvidos já há trinta anos. Neste artigo são apresentados os principais impactos de quantidade e de qualidade produzidos na drenagem, as medidas de controle atuais, as medidas sustentáveis a serem perseguidas no país e por um Plano Diretor de Drenagem Urbana, mecanismo de implementação das medidas sustentáveis na drenagem

Urban waters

Urban Waters systems generally include both water supply & sanitation facilities (WSS). Sanitation refers to domestic and industrial sewage collecting and treatment; it does not include urban stormwater or solid waste management systems. Urban water form components of a sustainable urban environment and the use of the integrated water resource management (IWRM) concepts are needed for planning, implementation and maintenance of urban infrastructure. In urban environment, IWRM is referred to specifically as Integrated Urban Water Management (IUWM). In this paper urban development and its relations with urban waters in Brazil are assessed. Management of Water Resources in Brazil is developed by basins and the administration is Federal or from the state. This article assess the alternatives of water management in the city and the basin in the Brazilian institutional environment.As águas urbanas geralmente incluem abastecimento de água e saneamento. Nessa perspectiva, saneamento envolve a coleta de tratamento de efluentes domésticos e industriais, não inclui drenagem urbana, gestão dos resíduos sólidos, porque ainda perdura uma visão desatualizada da gestão das águas urbanas da cidade. Águas urbanas envolvem componentes que permitem o desenvolvimento ambiental sustentável e utilizam os conceitos da gestão integrada dos recursos hídricos (GIRH), necessários para planejamento, implementação e manutenção da infra-estrutura da cidade. Nesse contexto, ficam denominados Gestão Integrada das Águas Urbanas. Neste artigo, analisam-se o desenvolvimento urbano e suas relações com as águas urbanas no Brasil. A gestão dos recursos hídricos no Brasil é realizada por bacias hidrográficas, e o domínio é federal ou estadual. Examinam-se as possibilidades de gestão da água na cidade e na bacia hidrográfica no contexto institucional brasileiro

CONSUMO EFICIENTE, CONSERVAÇÃO E CARACTERÍSTICAS SOCIODEMOGRÁFICAS QUE INFLUENCIAM NO CONSUMO DE ÁGUA

A água é considerada um dos poucos recursos que possui influênciaincontestável para a sobrevivência humana, motivo pelo qual as estratégias degestão para sua conservação são tão importantes. Nesse cenário, o objetivodeste estudo é identificar as características dos usos finais de água residencialurbana, assim como os fatores que influenciam na conservação, no consumoeficiente,assim como a influência sociodemográficano consumo de água. Ametodologia empregada consiste na abordagem quali-quantitativa.Oprocedimento técnico, caracteriza-se em uma pesquisa bibliográfica, noperíodo de 1999 a 2013. Os resultados refletem que o maior consumidor, emmédia de água, é o chuveiro, e a média de redução via equipamentos foi30,5%. Os fatores que influenciam na conservação da água e a influênciasociodemográficaforam identificados e detalhados. Conclui-se que na gestãoestratégica da demanda de água sejam considerados os resultados destapesquisa, de modo apromover a conservação e o consumo eficiente da águaresidencial urbana

Uncertainty in climate change impacts on water resources in the Rio Grande Basin, Brazil

We quantify uncertainty in the impacts of climate change on the discharge of Rio Grande, a major tributary of the Paraná River in South America and one of the most important basins in Brazil for water supply and hydro-electric power generation. We consider uncertainty in climate projections associated with the greenhouse-gas emission scenarios (A1b, A2, B1, B2) and increases in global mean air temperature of 1 to 6° C for the HadCM3 GCM (Global Circulation Model) as well as uncertainties related to GCM structure. For the latter, multimodel runs using 6 GCMs (CCCMA CGCM31, CSIRO Mk30, IPSL CM4, MPI ECHAM5, NCAR CCSM30, UKMO HadGEM1) and HadCM3 as baseline, for a +2° C increase in global mean temperature. Pattern-scaled GCM-outputs are applied to a large-scale hydrological model (MGB-IPH) of Rio Grande Basin. Based on simulations using HadCM3, mean annual river discharge increases, relative to the baseline or control run period (1961–1990), by +5% to +10% under the SRES emissions scenarios and from +8% to +51% with prescribed increases in global mean air temperature of between 1 and 6° C. Substantial uncertainty in projected changes to mean river discharge (−28% to +13%) under the 2° C warming scenario is, however, associated with the choice of GCM. We conclude that, in the case of Rio Grande Basin, the most important source of uncertainty derives from the GCM rather than the emission scenario or the magnitude of rise in mean global temperature

Modeling the role of reservoirs versus floodplains on large-scale river hydrodynamics

Large-scale hydrologic–hydrodynamic models are powerful tools for integrated water resources evaluation at the basin scale, especially in the context of flood hazard assessment. However, recent model developments have paid little attention to simulate reservoirs’ hydrodynamics within river networks. This study presents an adaptation of the MGB model to simulate reservoirs as an internal boundary condition, enabling the explicit simulation of hydrodynamic processes along reservoirs and their interaction with upstream and downstream floodplains in large basins. A case study is carried out in the Itajaí-Açu River Basin in Brazil, which has periodic flood-related disasters and three flood control dams. The model was calibrated for the 1950–2016 period forced with daily observed precipitation. The adjustment was satisfactory, with Nash–Sutcliffe metrics between 0.54 and 0.84 for the 11 gauges analyzed and with flood frequency curves also well represented. Simulation scenarios with and without floodplains and reservoirs were performed to evaluate the relative role of these factors on flood control basin-wide through evaluation of simulated discharges, water levels and flood extent. Itajaí do Oeste tributary and Itajaí-Açu mainstem present major floodplain attenuation, while in Itajaí do Sul and Itajaí do Norte tributaries the main flood control occurs due to reservoir attenuation. Downstream from the dams, results indicated that the reservoirs reach their maximum discharge reduction capacity for 5- to 10-year floods, decreasing it for larger floods. The developed model may be very useful for operational uses as flood forecasting and coordinated reservoir operation studies, as well as to enhance the comprehension of flood dynamics at basin scale