950 resultados para municipal water supply
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We report results from experimental water markets in which owners of two different sources of water supply water to households and farmers. The final water quality consumed by each type of consumer is determined through mixing of qualities from two different resources. We compare the standard duopolistic market structure with an alternative market clearing mechanism inspired by games with confirmed strategies (which have been shown to yield collusive outcomes). As in the static case, complex dynamic markets operating under a confirmed proposals protocol yield less efficient outcomes because coordination among independent suppliers has the usual effects of restricting output and increasing prices to the users. Our results suggest that, when market mechanisms are used to allocate water to its users, the rule of thumb used by competition authorities can also serve as a guide towards water market regulation.
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The catchment of the River Thames, the principal river system in southern England, provides the main water supply for London but is highly vulnerable to changes in climate, land use and population. The river is eutrophic with significant algal blooms with phosphorus assumed to be the primary chemical indicator of ecosystem health. In the Thames Basin, phosphorus is available from point sources such as wastewater treatment plants and from diffuse sources such as agriculture. In order to predict vulnerability to future change, the integrated catchments model for phosphorus (INCA-P) has been applied to the river basin and used to assess the cost-effectiveness of a range of mitigation and adaptation strategies. It is shown that scenarios of future climate and land-use change will exacerbate the water quality problems, but a range of mitigation measures can improve the situation. A cost-effectiveness study has been undertaken to compare the economic benefits of each mitigation measure and to assess the phosphorus reductions achieved. The most effective strategy is to reduce fertilizer use by 20% together with the treatment of effluent to a high standard. Such measures will reduce the instream phosphorus concentrations to close to the EU Water Framework Directive target for the Thames.
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This paper describes the hydrochemistry of a lowland, urbanised river-system, The Cut in England, using in situ sub-daily sampling. The Cut receives effluent discharges from four major sewage treatment works serving around 190,000 people. These discharges consist largely of treated water, originally abstracted from the River Thames and returned via the water supply network, substantially increasing the natural flow. The hourly water quality data were supplemented by weekly manual sampling with laboratory analysis to check the hourly data and measure further determinands. Mean phosphorus and nitrate concentrations were very high, breaching standards set by EU legislation. Though 56% of the catchment area is agricultural, the hydrochemical dynamics were significantly impacted by effluent discharges which accounted for approximately 50% of the annual P catchment input loads and, on average, 59% of river flow at the monitoring point. Diurnal dissolved oxygen data demonstrated high in-stream productivity. From a comparison of high frequency and conventional monitoring data, it is inferred that much of the primary production was dominated by benthic algae, largely diatoms. Despite the high productivity and nutrient concentrations, the river water did not become anoxic and major phytoplankton blooms were not observed. The strong diurnal and annual variation observed showed that assessments of water quality made under the Water Framework Directive (WFD) are sensitive to the time and season of sampling. It is recommended that specific sampling time windows be specified for each determinand, and that WFD targets should be applied in combination to help identify periods of greatest ecological risk. This article is protected by copyright. All rights reserved.
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Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response.
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Irrigation is a major husbandry tool, vital for world food production and security. The purpose of this review is twofold:- firstly drawing attention to the beneficial and deleterious aspects of irrigation resulting from interactions with the microbial world; secondly, forming a basis for encouraging further research and development. Irrigation is for example, a valuable component in the control of some soil borne pathogens such as Streptomyces scabies, the cause of potato common scab and Fusarium cubense, a cause of banana wilt. By contrast, applying irrigation encourages some foliar pathogens and factors such as splash dispersal of propagules and the retention of leaf wetness are important elements in the successful establishment of disease foci. Irrigation applied at low levels in the canopy directly towards the stem bases and root zones of plants also provides means encouraging disease development. Irrigation also offers means for the direct spread of microbes such as water borne moulds, Oomycetes, and plasmodial pathogens coming from populations present in the water supply. The presence of plant disease causing microbes in sources of irrigation has been associated with outbreaks of diseases such as clubroot (Plasmodiophora brassicae). Irrigation can be utilised as a means for applying agrochemicals, fungigation. The developing technologies of water restriction and root zone drying also have an impact on the success of disease causing organisms. This is an emerging technology and its interactions with benign and pathogenic microbes require consideration.
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In 2004 the National Household Survey (Pesquisa Nacional par Amostras de Domicilios - PNAD) estimated the prevalence of food and nutrition insecurity in Brazil. However, PNAD data cannot be disaggregated at the municipal level. The objective of this study was to build a statistical model to predict severe food insecurity for Brazilian municipalities based on the PNAD dataset. Exclusion criteria were: incomplete food security data (19.30%); informants younger than 18 years old (0.07%); collective households (0.05%); households headed by indigenous persons (0.19%). The modeling was carried out in three stages, beginning with the selection of variables related to food insecurity using univariate logistic regression. The variables chosen to construct the municipal estimates were selected from those included in PNAD as well as the 2000 Census. Multivariate logistic regression was then initiated, removing the non-significant variables with odds ratios adjusted by multiple logistic regression. The Wald Test was applied to check the significance of the coefficients in the logistic equation. The final model included the variables: per capita income; years of schooling; race and gender of the household head; urban or rural residence; access to public water supply; presence of children; total number of household inhabitants and state of residence. The adequacy of the model was tested using the Hosmer-Lemeshow test (p=0.561) and ROC curve (area=0.823). Tests indicated that the model has strong predictive power and can be used to determine household food insecurity in Brazilian municipalities, suggesting that similar predictive models may be useful tools in other Latin American countries.
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Leaves comprise most of the vegetative body of tank bromeliads and are usually subjected to strong longitudinal gradients. For instance, while the leaf base is in contact with the water accumulated in the tank, the more light-exposed middle and upper leaf sections have no direct access to this water reservoir. Therefore, the present study attempted to investigate whether different leaf portions of Guzmania monostachia, a tank-forming C(3)-CAM bromeliad, play distinct physiological roles in response to water shortage, which is a major abiotic constraint in the epiphytic habitat. Internal and external morphological features, relative water content, pigment composition and the degree of CAM expression were evaluated in basal, middle and apical leaf portions in order to allow the establishment of correlations between the structure and the functional importance of each leaf region. Results indicated that besides marked structural differences, a high level of functional specialization is also present along the leaves of this bromeliad. When the tank water was depleted, the abundant hydrenchyma of basal leaf portions was the main reservoir for maintaining a stable water status in the photosynthetic tissues of the apical region. In contrast, the CAM pathway was intensified specifically in the upper leaf section, which is in agreement with the presence of features more suitable for the occurrence of photosynthesis at this portion. Gas exchange data indicated that internal recycling of respiratory CO(2) accounted for virtually all nighttime acid accumulation, characterizing a typical CAM-idling pathway in the drought-exposed plants. Altogether, these data reveal a remarkable physiological complexity along the leaves of G. monostachia, which might be a key adaptation to the intermittent water supply of the epiphytic niche. (C) 2009 Elsevier GmbH. All rights reserved.
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A high incidence of waterborne diseases is observed worldwide and in order to address contamination problems prior to an outbreak, quantitative microbial risk assessment is a useful tool for estimating the risk of infection. The objective of this paper was to assess the probability of Giardia infection from consuming water from shallow wells in a peri-urban area. Giardia has been described as an important waterborne pathogen and reported in several water sources, including ground waters. Sixteen water samples were collected and examined according to the US EPA (1623, 2005). A Monte Carlo method was used to address the potential risk as described by the exponential dose response model. Giardia cysts occurred in 62.5% of the samples (0.1-36.1 cysts/l). A median risk of 10-1 for the population was estimated and the adult ingestion was the highest risk driver. This study illustrates the vulnerability of shallow well water supply systems in peri-urban areas.
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Drinking water utilities in urban areas are focused on finding smart solutions facing new challenges in their real-time operation because of limited water resources, intensive energy requirements, a growing population, a costly and ageing infrastructure, increasingly stringent regulations, and increased attention towards the environmental impact of water use. Such challenges force water managers to monitor and control not only water supply and distribution, but also consumer demand. This paper presents and discusses novel methodologies and procedures towards an integrated water resource management system based on advanced ICT technologies of automation and telecommunications for largely improving the efficiency of drinking water networks (DWN) in terms of water use, energy consumption, water loss minimization, and water quality guarantees. In particular, the paper addresses the first results of the European project EFFINET (FP7-ICT2011-8-318556) devoted to the monitoring and control of the DWN in Barcelona (Spain). Results are split in two levels according to different management objectives: (i) the monitoring level is concerned with all the aspects involved in the observation of the current state of a system and the detection/diagnosis of abnormal situations. It is achieved through sensors and communications technology, together with mathematical models; (ii) the control level is concerned with computing the best suitable and admissible control strategies for network actuators as to optimize a given set of operational goals related to the performance of the overall system. This level covers the network control (optimal management of water and energy) and the demand management (smart metering, efficient supply). The consideration of the Barcelona DWN as the case study will allow to prove the general applicability of the proposed integrated ICT solutions and their effectiveness in the management of DWN, with considerable savings of electricity costs and reduced water loss while ensuring the high European standards of water quality to citizens.
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Drinking water distribution networks risk exposure to malicious or accidental contamination. Several levels of responses are conceivable. One of them consists to install a sensor network to monitor the system on real time. Once a contamination has been detected, this is also important to take appropriate counter-measures. In the SMaRT-OnlineWDN project, this relies on modeling to predict both hydraulics and water quality. An online model use makes identification of the contaminant source and simulation of the contaminated area possible. The objective of this paper is to present SMaRT-OnlineWDN experience and research results for hydraulic state estimation with sampling frequency of few minutes. A least squares problem with bound constraints is formulated to adjust demand class coefficient to best fit the observed values at a given time. The criterion is a Huber function to limit the influence of outliers. A Tikhonov regularization is introduced for consideration of prior information on the parameter vector. Then the Levenberg-Marquardt algorithm is applied that use derivative information for limiting the number of iterations. Confidence intervals for the state prediction are also given. The results are presented and discussed on real networks in France and Germany.
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This study contributes a rigorous diagnostic assessment of state-of-the-art multiobjective evolutionary algorithms (MOEAs) and highlights key advances that the water resources field can exploit to better discover the critical tradeoffs constraining our systems. This study provides the most comprehensive diagnostic assessment of MOEAs for water resources to date, exploiting more than 100,000 MOEA runs and trillions of design evaluations. The diagnostic assessment measures the effectiveness, efficiency, reliability, and controllability of ten benchmark MOEAs for a representative suite of water resources applications addressing rainfall-runoff calibration, long-term groundwater monitoring (LTM), and risk-based water supply portfolio planning. The suite of problems encompasses a range of challenging problem properties including (1) many-objective formulations with 4 or more objectives, (2) multi-modality (or false optima), (3) nonlinearity, (4) discreteness, (5) severe constraints, (6) stochastic objectives, and (7) non-separability (also called epistasis). The applications are representative of the dominant problem classes that have shaped the history of MOEAs in water resources and that will be dominant foci in the future. Recommendations are provided for which modern MOEAs should serve as tools and benchmarks in the future water resources literature.
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The city of Natal comprises an area of about 170 km² (65,63 squares miles). The Dunas-Barreiras Aquifer is the most important reservoir of the coastal basin of RN. It is being responsible for the water supplying of about 70% of the population, however, due to the sewage disposal system by cesspools and drains, it is presently affected in a great extent by nitrates contamination. Thus, the present work proposes to research the utilization of contaminated water by nitrates of this fountainhead and find cost of the potable water through the ionic exchange technology. This technology consists in the removal of mineral salts by the exchange of cations for one ion of hydrogen (H+), through the passage of water by cationic resin bed and, secondly, by the exchange of the anions for hydroxyl ions (OH-) through a anionic resin bed. The obtained results have showed the waters derived from fountains, big water holes and shallow wells were microbiologically contaminated, while the waters derived from deep wells (above 70 m 76,58 yards) were free of contamination. Thus, only these ones are suitable to the use of ionic technology. The experiments were conducted with the resin IMAC-HP-555 such as kinetic, thermodynamic, and adsorption by fixed bed studies, being obtained several project variables for the experimental column, as follow: work temperature of 25oC; resin maximum capacity maximum e mean of adsorption ==0,01692 g NO3-1/g R e 0,0110 g NO3-1/g R, respectively. On the experimental column were performed breakthrough tests which pointed for an average ideal average speed of work of 13.2 m / h, with an average efficiency of 45% of adsorption, an optimal concentration of NaCl desorption of 8%, and an ideal desorption time of 80 minutes for the equilibrium conditions of water from the Dunas-Barreiras aquifer. Scale projection for ion-exchange column for denitrification, for these variables, using a computer modeling programme, to project the column of ion exchange ROREX-420/2000, obtained a cost for the drinking water denitrified by this system of R$ 0,16 / m3
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This study determined the prevalence of cavitated caries lesions (CCL) and early childhood caries (ECC), and the contribution of some variables in children up to 36 months of age attending daycare centers in municipalities with different fluoride levels in the water supply: AFC (adequate fluoride content) and LFC (low fluoride content). After approval of the Ethics Committee, the parents were interviewed. The children were clinically examined using the same codes and criteria established by the WHO (World Health Organization) and the ADA (American Dental Association). Fisher's exact test (p<0.05) was applied for statistical analysis of data. The dmft indices calculated in the LFC and AFC municipalities were 0.57 and 0.68, respectively. Considering all children examined, 17.6% presented CCL and 33.8% ECC. The economic classification, mother's education level and duration of breastfeeding were considered statistically significant with regards to CCL prevalence. The age group, duration of the habit of drinking milk before bedtime and age at which oral hygiene started were considered statistically significant with regards to ECC prevalence.
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The effects and interaction of drought and UV-B radiation were studied in sunflower plants (Helianthus annuus L. var. Catissol-01), growing in a greenhouse under natural photoperiod conditions. The plants received approximately 1.7 W m(-2) (controls) or 8.6 W m(-2) (+UV-B) of UV-B radiation for 7 h per day. The UV-B and water stress treatments started 18 days after sowing. After a period of 12 days of stress, half of the water-stressed plants (including both UV-B irradiated or non-irradiated) were rehydrated. Both drought and UV-B radiation treatments resulted in lower shoot dry matter per plant, but there was no significant interaction between the two treatments. Water stress and UV-B radiation reduced photosynthesis, stomatal conductance and transpiration. However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercelluar CO(2) concentration was initially reduced in all treatments compared to control plants but it increased with time. Photosynthetic pigments were not affected by UV-B radiation. Water stress reduced photosynthetic pigments only under high UV-B radiation. The decrease was more accentuated for chlorophyll a than for chlorophyll b. As a measure for the maximum efficiency of photosystem II in darkness F (v)/F (m) was used, which was not affected by drought stress but initially reduced by UV-B radiation. Independent of water supply, UV-B radiation increased the activity of pirogalol peroxidase and did not increase the level of malondialdehyde. on the other hand, water stress did not alter the activity of pirogalol peroxidase and caused membrane damage as assessed by lipid peroxidation. The application of UV-B radiation together with drought seemed to have a protective effect by lowering the intensity of lipid peroxidation caused by water stress. The content of proline was not affected by UV-B radiation but was increased by water stress under both low and high UV-B radiation. After 24 h of rehydration, most of the parameters analyzed recovered to the same level as the unstressed plants.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)