Parameter estimation in water-distribution systems by least squares

The weighted-least-squares method using sensitivity-analysis technique is proposed for the estimation of parameters in water-distribution systems. The parameters considered are the Hazen-Williams coefficients for the pipes. The objective function used is the sum of the weighted squares of the differences between the computed and the observed values of the variables. The weighted-least-squares method can elegantly handle multiple loading conditions with mixed types of measurements such as heads and consumptions, different sets and number of measurements for each loading condition, and modifications in the network configuration due to inclusion or exclusion of some pipes affected by valve operations in each loading condition. Uncertainty in parameter estimates can also be obtained. The method is applied for the estimation of parameters in a metropolitan urban water-distribution system in India.

Potential-distance relationships of clay-water systems considering the Stern theory

This paper deals with the use of Stem theory as applied to a clay-water electrolyte system, which is more realistic to understand the force system at micro level man the Gouy-Chapman theory. The influence of the Stern layer on potential-distance relationship has been presented quantitatively for certain specified clay-water systems and the results are compared with the Gouy-Chapman model. A detailed parametric study concerning the number of adsorption spots on the clay platelet, the thickness of the Stern layer, specific adsorption potential and the value of dielectric constant of the pore fluid in the Stern layer, was carried out. This study investigates that the potential obtained at any distance using the Stern theory is higher than that obtained by the Gouy-Chapman theory. The hydrated size of the ion is found to have a significant influence on the potential-distance relationship for a given clay, pore fluid characteristics and valence of the exchangeable ion.

Short- and long-term temporal variations in salinity and the oxygen, carbon and hydrogen isotopic compositions of the Hooghly Estuary water, India

The Hooghly River estuary provides a unique experimental site to understand the effect of monsoonal river discharge on freshwater and seawater mixing. Water samples collected bi-weekly for a duration of 17 months were analyzed for salinity, delta O-18,delta C-13(DIC), as well as delta D to investigate the differential mixing of freshwater and seawater. The differences in salinity and delta O-18 of samples collected during low and high tides on the same day are strongly correlated suggesting a well mixed water column at our sampling site. Low salinity and depleted delta O-18 during monsoon is consistent with increased river discharge as well as high rainfall. We identified different slopes in a delta O-18 versus salinity plot for the estuary water samples collected during monsoon and non-monsoon seasons. This is driven by composition of the freshwater source which is dominated by rainwater during monsoon and rivers during non-monsoon months. Selected delta D analyses of samples indicate that groundwater contributes significantly to the Hooghly Estuary during low rainfall times of the year. delta C-13(DIC) measured in the water recorded low values towards the end of monsoon indicating low productivity (i.e. increased organic respiration) while progressively increasing delta C-13(DIC) values from October till January as well as during some of the pre-monsoon months can be explained by increasing productivity. Very low delta C-13(DIC) (similar to-20%0) suggests involvement of carbon derived from anaerobic oxidation of organics and/or methane with potential contribution from increased anthropogenic water supply. An estimate of seawater incursion into the Hooghly Estuary at different times of the year is obtained by using salinity data in a two-component mixing model. Presence of seawater was found maximum (31-37%) during February till July and lowest (less than or equal to 6%) from September till November. We notice a temporal offset between Ganges River discharge farther upstream at Farakka and salinity variation at the Hooghly Estuary. We believe that this time lag is a result of the physical distance between Farakka and Kakdweep (our sampling location) and put constraints on the travel time of river water during early monsoon. (c) 2012 Published by Elsevier B.V.

Impacts of climate change on regional water resources

Water is the most important medium through which climate change influences human life. Rising temperatures together with regional changes in precipitation patterns are some of the impacts of climate change that have implications on water availability, frequency and intensity of floods and droughts, soil moisture, water quality, water supply and water demands for irrigation and hydropower generation. In this article we provide an introduction to the emerging field of hydrologic impacts of climate change with a focus on water availability, water quality and irrigation demands. Climate change estimates on regional or local spatial scales are burdened with a considerable amount of uncertainty, stemming from various sources such as climate models, downscaling and hydrological models used in the impact assessments and uncertainty in the downscaling relationships. The present article summarizes the recent advances on uncertainty modeling and regional impacts of climate change for the Mahanadi and Tunga-Bhadra Rivers in India.

Reliability Assessment of a Storm Water Drain Network

Most of the cities in India are undergoing rapid development in recent decades, and many rural localities are undergoing transformation to urban hotspots. These developments have associated land use/land cover (LULC) change that effects runoff response from catchments, which is often evident in the form of increase in runoff peaks, volume and velocity in drain network. Often most of the existing storm water drains are in dilapidated stage owing to improper maintenance or inadequate design. The drains are conventionally designed using procedures that are based on some anticipated future conditions. Further, values of parameters/variables associated with design of the network are traditionally considered to be deterministic. However, in reality, the parameters/variables have uncertainty due to natural and/or inherent randomness. There is a need to consider the uncertainties for designing a storm water drain network that can effectively convey the discharge. The present study evaluates performance of an existing storm water drain network in Bangalore, India, through reliability analysis by Advance First Order Second Moment (AFOSM) method. In the reliability analysis, parameters that are considered to be random variables are roughness coefficient, slope and conduit dimensions. Performance of the existing network is evaluated considering three failure modes. The first failure mode occurs when runoff exceeds capacity of the storm water drain network, while the second failure mode occurs when the actual flow velocity in the storm water drain network exceeds the maximum allowable velocity for erosion control, whereas the third failure mode occurs when the minimum flow velocity is less than the minimum allowable velocity for deposition control. In the analysis, runoff generated from subcatchments of the study area and flow velocity in storm water drains are estimated using Storm Water Management Model (SWMM). Results from the study are presented and discussed. The reliability values are low under the three failure modes, indicating a need to redesign several of the conduits to improve their reliability. This study finds use in devising plans for expansion of the Bangalore storm water drain system. (C) 2015 The Authors. Published by Elsevier B.V.

Use of Data Driven Techniques for Short Lead Time Streamflow Forecasting in Mahanadi basin

Streamflow forecasts at daily time scale are necessary for effective management of water resources systems. Typical applications include flood control, water quality management, water supply to multiple stakeholders, hydropower and irrigation systems. Conventionally physically based conceptual models and data-driven models are used for forecasting streamflows. Conceptual models require detailed understanding of physical processes governing the system being modeled. Major constraints in developing effective conceptual models are sparse hydrometric gauge network and short historical records that limit our understanding of physical processes. On the other hand, data-driven models rely solely on previous hydrological and meteorological data without directly taking into account the underlying physical processes. Among various data driven models Auto Regressive Integrated Moving Average (ARIMA), Artificial Neural Networks (ANNs) are most widely used techniques. The present study assesses performance of ARIMA and ANNs methods in arriving at one-to seven-day ahead forecast of daily streamflows at Basantpur streamgauge site that is situated at upstream of Hirakud Dam in Mahanadi river basin, India. The ANNs considered include Feed-Forward back propagation Neural Network (FFNN) and Radial Basis Neural Network (RBNN). Daily streamflow forecasts at Basantpur site find use in management of water from Hirakud reservoir. (C) 2015 The Authors. Published by Elsevier B.V.

Environmental Mechanics Research in China

By recalling mankind's path during past 50 years in the present article, we mainly highlight the significance of environmental issues today. In particular, two major factors leading to environment deterioration in China such as water resources and coal burning are stressed on. Present-day environmental issues are obviously interdisciplinary, of multiple scales and multi-composition in nature. Therefore, a process-based approach for environment research is absolutely necessarily. A series of sub-processes, either physical, chemical or biological, are subsequently analyzed in order to established reasonable parameterization scheme and credible comprehensive model. And we are now in a position to answer questions still open to us, improve existing somewhat empirical engineering approaches and enhance quantitative accuracy in prediction. To illustrate this process-based research approach, three typical examples associated with the Yangtze River Estuary, Loess Plateau and Tenggeli Desert environments have been dealt with respectively. A theoretical model of vertical flow field accounting for runoff and tide interaction has been established to delineate salinity and sediment motion which are responsible for the formation of mouth bar at the outlet and the ecological evolution there. A kinematic wave theory combined with the revised Green-Ampt infiltration formula is applied to the prediction of runoff generation and erosion in three types of erosion region on the Loess Plateau. Three approaches describing water motion in SPAC system in arid areas at different levels have been improved by introducing vegetation sub-models. However, we have found that the formation of a dry sandy layer and biological crust skin are additional primary causes leading to deterioration of water supply and succession of ecological system.

Nationwide-US newspaper coverage of handling water contamination : a community structure approach

Resumen: Empleando la teoría de la “estructura comunitaria”, un muestreo de diarios principales en 28 ciudades grandes en Estados Unidos examina la cobertura del tema “El manejo de contaminación de agua y acceso a agua potable”. Mediante el análisis de todos los artículos de más de 250 palabras publicados a través de diez años entre 01/01/2001 y 01/01/2011 (339 artículos), se compararon sistemáticamente características comunitarias y el “Vector Mediático” de Pollock (combinando en un valor dos medidas de contenido: la “prominencia” de un artículo en un periódico con la orientación o tono). Cobertura “favorable”, que apoya la mayor ayuda gubernamental para mejorar el abastecimiento de agua potable, fue vinculada con medidas de “los interesados”, por ejemplo, con el porcentaje de hispanos (r de Pearson = .349, p = .04). El análisis de las medidas y su regresión reveló dos medidas significativas asociadas con apoyo para manejo gubernamental por agua potable: porcentaje de hispanos (12.2% de la varianza), y con porcentaje de ciudadanos de 18-24 años, 16.7%. Inesperadamente, la cobertura de manejo gubernamental para mejorar las existencias de agua potable no fue vinculado ni con medidas de “vulnerabilidad” (pobreza, desempleo) ni con medidas de “estabilidad” (educación, ingreso).

El abastecimiento de agua corriente en la ciudad de Córdoba (1900-1910) : continuidad y cambio en la gestión

Resumen: Desde un punto de vista general el agua es definida en la actualidad como un recurso natural no renovable en cantidad, recuperable en calidad y con posibilidad de nuevo uso (re-uso) en continua mutación dentro del ciclo hidrológico. A la vez posee las categorías de bien común como elemento esencial para la vida humana y que como tal no tiene precio, y de recurso hídrico con dimensión económica como insumo, que supone un valor mensurable. Los recursos hídricos y su gestión forman parte de la administración pública, como pueden serlo la energía o la salud. La organización adecuada de un servicio, y las formas institucionales a través de las que se presta, varían de acuerdo a las épocas, los costes tecnológicos, los de distribución, organización y regulación, resultando un aspecto importante del análisis la implementación y funcionamiento del servicio público. Atendiendo a estos aspectos teóricos, este trabajo continua con la problemática del abastecimiento de agua corriente en la ciudad de Córdoba, ahora en la primera década del siglo XX, manteniendo el supuesto de que las dificultades para el abastecimiento de agua obedecen a razones de orden natural, a dificultades económicas y a enfrentamientos políticos, en el marco de un Estado que aún posee limitaciones de índole institucional y administrativo, por lo cual intervendrán el gobierno provincial y Nacional para la concreción de las obras de salubridad, en una ciudad y un país enrolados en el proceso de modernización impulsado por el deseo de adecuación al modelo de vida europeo. Seguimos analizando las fuentes inéditas del Archivo Histórico Municipal de Córdoba, fuentes oficiales editas, publicaciones periódicas y bibliografía tanto general como específica.

Reconnaissance of the ground-water resources of the Fernandina area, Nassau County, Florida

Practically all water for municipal and industrial use in the Fernandina area is supplied by artesian wells. In recent years, the use of artesian water in the area has increased to meet the needs of expanding industry and increasing population. The total industrial and municipal pumpage has increased from approximately 35 million gallons per day in 1941 to approximately 50 million gallons per day in 1959. Correlated with the increase in water use is the constant decline in the artesian pressure in the area. In many other areas in Florida, such a decline in artesian pressure has resulted in salt-water intrusion into the fresh-water supply.An intrusion of salt water in the Fernandina area would contaminate the existing fresh-water supply and would result in a hardship for the population and seriously injure the economy. Recognizing the threat to the fresh-water supplies of this area, the U. S. Geological Survey in cooperation with the Florida Geological Surveymade a reconnaissance to determineif there has been any intrusion of salt water into the fresh-water supply or if there is any danger of future intrusion. (PDF contains 28 pages.)

The Costs of Drought: the Exceptional 2007-2008 Case of Barcelona

35 p.

Cidades secas, vidas secas: A trajetória das águas e sua regulamentação no Rio de Janeiro sob uma perspectiva urbano-ambiental

Esta tese analisará a distribuição das águas na cidade do Rio de Janeiro considerando os elementos sociais, jurídicos, políticos, e seus reflexos no direito urbano e ambiental. Nesse aspecto referenciará as medidas de regulação e de organização da estrutura urbana, desde a formação da cidade até os dias atuais, assim como as consequências da exclusão e da ausência das políticas urbanas equitativas. No início, as ocupações irregulares, se distantes do centro e dos bairros elitizados, não despertavam maiores demandas do poder público, porém com o aumento das periferias e as ocupações próximas aos bairros formais, inúmeras medidas adotadas optaram pela remoção, contenção e a destruição dos espaços sem apresentar uma solução, agravando os problemas urbanos. Tais problemas, reconhecidamente sociais, passam a ser denominados urbanos e ambientais, gerando uma complexa criminalização dos moradores das periferias. As intervenções nos espaços são legalizadas pelo instrumento jurídico, as residências suburbanas são classificadas como ilegais e, por consequência, os recursos que deveriam atender a todos na cidade são direcionados apenas para cidade legalizada, criando a celeuma da desigualdade. Assim, amontoados em barracos precários, sem abastecimento de água, energia, esgoto e coleta de lixo, as periferias multiplicam as diversas formas de violência, uma vez que o direito não socorre esses moradores que, abandonados pela lei, vivem a escassez das águas e a especulação dos serviços ilegais de abastecimento. A crise do abastecimento não é causada pelas populações mais empobrecidas, mas pelo mercado que se apropria da maior parte desses recursos, dentro do sistema de uma lógica capitalista, e exclui aqueles que não podem pagar pelo abastecimento regular. Nesse sentido, este trabalho entende que o direito, ainda que tenha se tornado regulatório pode assumir um caráter revolucionário e transformador em que o direito das águas seja um direito da comunidade, por isso, um bem público não estatal, por fim objetiva esse trabalho estudar as leis das águas dentro do paradigma da solidariedade hídrica.

Atlas digital: uma contribuição para o sistema de informação do município de São João de Meriti-RJ

Um Atlas Digital é um atlas que foi concebido através de técnicas computacionais e que, consequentemente, pode ser acessado através de um computador. Estruturado em um ambiente gráfico, além dos mapas, pode-se contar também com textos, fotografias, dados estatísticos, gráficos e tabelas. Por estar em meio digital existe a possibilidade de utilização de uma expressiva gama de temas, formatos e escalas. Nesta dissertação apresenta-se um protótipo de Atlas Digital como uma colaboração ao Sistema de Informação Municipal SIM, para o município de São João de Meriti, RJ. O referido SIM, que tem como meta os serviços municipais, visa atender ao próprio município, ao cidadão e a outros interessados na cidade, sendo as suas informações fundamentais para a melhoria da gestão das prefeituras. A pesquisa foi direcionada para o tema da habitabilidade, que consiste num conjunto de condições voltadas para a construção de habitat saudável, abrangendo temas físicos, psicológicos, sociais, culturais e ambientais. Dentro do tema habitabilidade, foram trabalhados os subtemas relativos a infraestrutura de abastecimento de água, esgoto, coleta de lixo, saúde e educação, esses subtemas foram confrontados entre si para uma comparação entre os bairros do município. O SIM e a habitabilidade são contemplados no plano diretor da cidade e representa uma grande parte da sustentação teórica da dissertação. A modelagem e implementação do protótipo do Atlas Digital foram feitas com auxílio de softwares gratuitos, sendo possível acessar mapas temáticos e outras informações sobre São João de Meriti

Temporal and spatial variations in the quality of water in El Gergal Reservior, Seville, Spain

It is often difficult to define ‘water quality’ with any degree of precision. One approach is that suggested by Battarbee (1997) and is based on the extent to which individual lakes have changed compared with their natural ‘baseline’ status. Defining the base-line status of artificial lakes and reservoirs however, is, very difficult. In ecological terms, the definition of quality must include some consideration of their functional characteristics and the extent to which these characteristics are self-sustaining. The challenge of managing lakes in a sustainable way is particularly acute in semi-arid, Mediterranean countries. Here the quality of the water is strongly influenced by the unpredictability of the rainfall as well as year-to-year variations in the seasonal averages. Wise management requires profound knowledge of how these systems function. Thus a holistic approach must be adopted and the factors influencing the seasonal dynamics of the lakes quantified over a range of spatial and temporal scales. In this article, the authors describe some of the ways in which both long-term and short-term changes in the weather have influenced the seasonal and spatial dynamics of phytoplankton in El Gergal, a water supply reservoir situated in the south of Spain. The quality of the water stored in this reservoir is typically very good but surface blooms of algae commonly appear during warm, calm periods when the water level is low. El Gergal reservoir is managed by the Empresa Municipal de Abastecimiento y Saneamiento (EMASESA) and supplies water for domestic, commercial and industrial use to an area which includes the city of Seville and twelve of its surrounding towns (ca. 1.3 million inhabitants). El Gergal is the last of two reservoirs in a chain of four situated in the Rivera de Huelva basin, a tributary of the Guadalquivir river. It was commissioned by EMASESA in 1979 and since then the company has monitored its main limnological parameters on, at least, a monthly basis and used this information to improve the management of the reservoir. As a consequence of these intensive studies the physical, chemical and biological information acquired during this period makes the El Gergal database one of the most complete in Spain. In this article the authors focus on three ‘weather-related’ effects that have had a significant impact on the composition and distribution of phytoplankton in El Gergal: (i) the changes associated with severe droughts; (ii) the spatial variations produced by short-term changes in the weather; (iii) the impact of water transfers on the seasonal dynamics of the dinoflagellate Ceratium.