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Membrane filtration is a key technology for producing freshwater sustainably. However, fouling is a major setback in this technology. Several studies have revealed that hydrodynamics significantly affects the fouling pattern. This review highlights the recent trends in the use of methods to visualize hydrodynamics and fouling in membrane filtration systems. These methods can be classified into invasive and non-invasive types. Invasive methods are predominantly used for root cause analysis of fouling and are more oriented towards industrial applications. The non-invasive methods such as computational fluid dynamics, biofouling simulation, and real-time fouling-monitoring are used to understand hydrodynamics in the membrane channel, the kinetics and mechanism of fouling deposition, etc., and aid substantially in laboratory-scale studies. These methods have shown great potential to predict membrane performance in real-scale applications. Since the non-invasive and invasive methods are "preventive" and "cure" types, respectively, the recent focus has shifted more towards non-invasive methods. This review paper comprehensively discusses these techniques along with an outline of the future scope of work. [ABSTRACT FROM AUTHOR]

Most critical flood problems occur in urban areas where values at risk are higher and damages tend to be heavier. In the present study, a hydrodynamic simulation of the river Yamuna has been generated under different designated flood flows to delineate the land availability under existing and modified riverbed geometry including channel dredging and riverbed dressing. Flood flows for various return periods, namely once in 10, 25, 50, and 100 years are estimated based on the past 41 years of recorded data using flood frequency analysis. The model set up considered the river stretch of 23 km from the Wazirabad barrage upstream to the Okhla barrage downstream, which includes manmade structures like bridges and barrages. Model calibration is achieved by comparing the water surface elevations with observed data at various downstream gauge stations. The land availability based on submergence scenarios under existing riverbed condition is estimated to be 1147.6, 873.1, and 762.6 ha, respectively, for 10, 50, and 100 year return flood. Various simulations are generated including channel dredging and riverbed dressing to obtain safe height and safe width for dressing the riverbed. The modified river geometry considered channel dredging in 750 to 1350 m width, and riverbed dressing for safe height and width in three levels in various sections. The land availability under this scenario is estimated to be 2197, 1129, and 545 ha for 10, 50, and 100 year return flood, respectively. It is proposed to dress the riverbed by utilizing the material obtained from channel dredging in three levels to maintain the transverse and longitudinal slope, river morphology, and river system. Developmental planning in the riverbed may include utilization of land at three levels for various purposes such as playgrounds, nursery, etc. However, it is suggested that the feasibility study of the project requires detailed engineering including slope stability prior to implementation of the riverbed development. Key words: hydrodynamic, simulation, flood, submergence, channelisation, riverbed dressing. La majorite des problemes de crues critiques survient dans les zones urbaines ou plus de valeurs sont en danger et ou les dommages ont tendance a etre plus importants. Dans la presente etude, la riviere Yamuna a ete simulee hydrodynamiquement en utilisant differents debits de crue afin de determiner la disponibilite des terres selon la geometrie existante et modifiee du lit de la riviere, comme par exemple, par dragage d'un canal ou amenagement du lit de la riviere. Les de bits de crue pour diverses periodicites, soit une fois a tous les 10, 25, 50 et 100 ans, sont estimes en se basant sur les 41 dernieres annees de donnees et en analysant la frequence des crues. Le reglage du modele a ete realise en utilisant un segment de riviere de 23 km entre le barrage de Wazirabad en amont et le barrage d'Okhla, en aval; ce segment comprend des structures telles que des ponts et des barrages. Le modele a ete etalonne en comparant les elevations des eaux de surface a des donnees obtenues a diverses stations de mesure en aval. La disponibilite des terres basees sur des scenarios de submergence est estimee etre 1147,6, 873,1 et 762,6 ha respectivement pour des periodicites de 10, 25, 50 et 100 ans. Diverses simulations ont ete produites en incorporant le dragage du canal et l'amenagement du lit de la riviere afin d'obtenir une hauteur et une largeur securitaires d'amenagement du lit de la riviere. La geometrie modifiee de la riviere tenait compte du dragage d'un canal de 750 a 1350 m de largeur et de l'amenagement du lit de la riviere pour obtenir une hauteur et une largeur securitaires pour trois niveaux a diverses sections. La disponibilite des terres selon ce scenario etait estimee a 2197, 1129 et 545 ha pour des periodicites respectives de 10, 25, 50 et 100 ans. Il est propose d'amenager le lit de la riviere en utilisant les materiaux obtenus lors du dragage du canal selon trois niveaux afin de maintenir les pentes transversale et longitudinale, la morphologie de la riviere et le reseau hydrographique. La planification du developpement du lit de la riviere peut inclure l'utilisation des terres selon trois niveaux pour des terrains de jeu, des pepinieres, etc. Toutefois, l'etude de faisabilite du projet devrait inclure une ingenierie detaillee de la stabilite des pentes avant la mise en oeuvre du des travaux sur le lit de la riviere. Mots-cles : hydrodynamique, simulation, crue, submergence, canalisation, amenagement du lit de riviere. [Traduit par la Redaction], 1. Introduction Flooding is an important natural process. It plays a vital role in the maintenance of floodplain and riverbed ecosystems, but also puts human life and property at risk [...]

Day to day activities of urban population in normal routine conditions are largely affected by the operation of the urban water supply system. In addition, the working hours, pattern of shift duties and living standards in a society decide the quantum of water use at different times in a day. This demand pattern is an important parameter for water supply agencies in order to ensure safe and reliable water supply. In the present study, short-term (hourly and daily) water demand is estimated for drinking as well as various other household activities. BIS standard of 135 lpcd and socioeconomic survey data are considered as the basis to derive a time series distribution of water consumption for different activities. Monte Carlo simulation (MCS) is performed to generate the random distribution of consumption pattern. The hourly water consumption for various activities shows persistent behavior with Hurst coefficient in the range of 0.592 to 0.837 and the peak flow factor of the estimated demand pattern is 5. This pattern is useful as a basis for design of service reservoir as well as pump scheduling. It is also an important parameter in the model study in performance assessment of water distribution system (WDS).

Water distribution system (WDS) is the most important component of water supply chain--supplying water from source to consumer. When supply system is poorly maintained, contaminants enter into the supply pipes through cracks and this leads to significant public health risk. Being underground, pipe condition assessment is a difficult task. In this paper, a case study is presented for assessment of pipe condition in a water distribution network of Moinbagh area in Hyderabad (India). The mathematical model-Pipe Condition Assessment (PCA) Model was used, which utilizes GIS based maps of water distribution network, sewer network, drains and soil as input in addition to data on physical properties of the network as well as operational parameters. The application of PCA identified that only 3% pipes in the network were in bad condition.

Groundwater quality data on physico-chemical, bacteriological and heavy metal concentrations in three cities (Faridabad, Allahabad and Varanasi) in Ganga-Yamuna basin was subjected to multivariate analysis (MVA) using SPSS. The factors extracted showed high loading (> 0.3) of various parameters, such as Cl, conductivity, TDS, hardness, Na, Mg, and SO4, indicating contamination due to leaching of pollutants. Major manifest variable associated with these factors is the unorganized solid waste dumping practiced in all the cities. Bacterial contamination of hand pump samples in Allahabad is attributed to surface water-groundwater interaction. The factor with high loading of Ca and F is indicative of geological conditions of the region. Wells in Yamuna river sub-watershed exhibit less freshwater recharge, which is attributed to surface water pollution and sediment deposition in the river. Thus, the methodology for hydrogeological analysis is useful to identify critical water quality issues and possible sources of pollution in river basins.