Showing papers in "Urban Water Journal in 2014"
TL;DR: A survey of frontier efficiency and productivity measurement in urban water utilities in Australia, the UK, Spain, the US, Mexico, Brazil, Canada, Germany, Italy, Malaysia and Slovenia can be found in this paper.
Abstract: Despite the rapid global revitalisation of urban water policy, and the universal need to measure and improve organizational efficiency and productivity in all suppliers as a means of ensuring the sustainability of this key resource, only recently have the most advanced econometric and mathematical programming frontier techniques been applied to urban water utilities. This paper provides a synoptic survey of the comparatively few empirical analyses of frontier efficiency and productivity measurement in urban water utilities in Australia, the UK, Spain, the US, Mexico, Brazil, Canada, Germany, Italy, Malaysia and Slovenia, among others. The survey examines both estimation and measurement techniques and the non-discretionary structural and regulatory determinants of efficiency and productivity. There is particular focus on how the results of past studies inform regulatory policy and managerial behaviour and key directions for future research.
92 citations
TL;DR: The results obtained show that the procedure makes it possible to identify very good solutions in terms of resilience and minimum pressures when reference to the peak demand and fire-flow conditions is made.
Abstract: This paper presents a procedure for the automatic creation of district metered areas (DMAs) in a water distribution system. The procedure uses techniques derived from graph theory (Breadth First Search and algorithm for finding the shortest paths in a graph) and demand-driven hydraulic simulations of the network in order to (a) divide the nodes among an assigned number of DMAs, (b) identify the ‘open’ links between districts where flow meters will be placed and (c) identify the ‘closed’ links between districts where isolation valves will be placed. The application of the proposed procedure to the case of a real water distribution system revealed it to be robust and effective. In particular, the results obtained show that the procedure makes it possible to identify very good solutions in terms of resilience and minimum pressures when reference to the peak demand and fire-flow conditions is made. The resulting performance indicators were better than those obtainable by applying a similar procedure previousl...
82 citations
TL;DR: In this paper, the authors identify conditions to engage the practitioners to inform their actions in regard to sustainable stormwater management, which is a strong barrier in the change process, to the neglect of the social aspects.
Abstract: The traditional use of piped systems for stormwater management is increasingly criticized as being ‘unsustainable’. These systems are part of the water domain where much research has focused on sustainable development indicators to support decision-makers in selecting systems that are more sustainable. However, the interest in sustainable development indicators is low. This paper identifies conditions to engage the practitioners to inform their actions in regard to sustainable stormwater management. Empirical evidence has been obtained from interviews with water professionals from Swedish municipalities. The environmental-technical discourse of sustainable stormwater development is a strong barrier in the change process, to the neglect of the social aspects. In the interviews, reframing the discourse was possible in visions of future sustainable stormwater systems embracing green infrastructure. In action, primary conditions can support sustainable pathways in realizing this vision. The paper suggests fur...
67 citations
TL;DR: In this paper, two heuristic methods coupled with ASib are proposed in order to reduce the number of feasible solutions in the search space, and the optimization results showed that the proposed heuristic approaches have considerably improved the quality of solutions produced by the ASib and enhanced the na...
Abstract: Despite considerable pumping energy costs in pumping stations of water distribution networks (WDNs), there are not many studies offering pumping schedule in order to optimize pumping energy costs regarding the WDN design. This paper aims to focus on the optimization of the WDN pumping station schedule by means of variable-speed pump (VSP) and using a combination of the ant system iteration best algorithm (ASib) and EPANET2.0. In fact, the VSP is implemented to increase the flexibility of pumping station and obtain the pumping schedule with optimized energy cost as the water demand changes during a day. Given that vast search space in optimization process leads to a decrease in the quality of final results, in this study, two heuristic methods coupled with ASib are proposed in order to reduce the number of feasible solutions in the search space. The optimization results showed that the proposed heuristic approaches have considerably improved the quality of solutions produced by the ASib and enhanced the na...
62 citations
Abstract: This study presents the results from a life cycle assessment (LCA) performed on the water and wastewater system in the city of Trondheim. The objective of the study was to examine the system-wide life cycle environmental impact potentials of operating the city's water and wastewater system, in order to clarify the relative importance of different environmental impact categories and how different elements of the water and wastewater system contribute to these impacts. As the results of this study were used in the planning of a new carbon-neutral urban settlement, the climate change impact was of special interest. Freshwater eutrophication due to the consumption of energy and chemicals was found to be the impact category with the largest contribution to the total environmental impact. In practice, urban water utilities would have to perform a trade-off between the consumption of energy and chemicals and the discharge of pollutants to receiving waters.
59 citations
TL;DR: In this article, storm water pollution in the first flush storm water runoff between sites with different traffic intensities within a town was compared, and the results showed that the levels of heavy metals and total phosphorus in storm water were highest at the site with the highest traffic intensity.
Abstract: Storm water quality was monitored at four sites in a middle-sized Swedish town. The objective was to compare storm water pollution in the first flush storm water runoff between sites with different traffic intensities within a town. Flow proportional storm water runoff samples were collected. The samples were analyzed for suspended solids, conductivity, total nitrogen, total phosphorus, oil index, lead, cadmium, copper, chromium, nickel, and zinc.The results showed that the levels of heavy metals and total phosphorus in storm water were highest at the site with the highest traffic intensity (7000 vehicles/day). A strong linear dependence between suspended solids (SS) and total phosphorus and heavy metals was observed. SS was the dominant explanatory variable for these parameters and a suitable predictor. The observed correlation between SS, heavy metals, and total phosphorus means that reducing levels of suspended solids in storm water would contribute to a substantial decrease of particle-bound heavy met...
49 citations
TL;DR: In this paper, a linear extension of the Yule process (LEP) is used to model the recurrent failures of pressure pipes in water supply networks and the likelihood of the parameters with respect to a sequence of observed failures is derived using productintegration.
Abstract: This paper shows how to construct, within the mathematical framework of counting process theory, a Linear Extension of the Yule Process (LEYP) to model the recurrent failures of pressure pipes in water supply networks. The choice of the counting process framework is motivated by an analysis of the advantages and shortcomings of the modelling approaches proposed in the literature over the last thirty years. The parametric nature of the LEYP model enables the prediction of future failures, accounting for the effect of previous failures, pipe ageing, and explanatory factors, assuming proportional hazards. The counting process is Markovian by definition and shown to follow a negative binomial distribution. This property leads to a useful and simple formula for computing conditional predictions given past observed failures. The likelihood of the parameters with respect to a sequence of observed failures is derived using product-integration. Maximum likelihood estimates of the model parameters can be calculated...
45 citations
TL;DR: In this article, a Partial Least Squares (PLS) calibration model was developed for TSS and COD prediction, based on UV-Vis spectra, and three approaches for model development were studied.
Abstract: Ultraviolet-visible (UV-Vis) spectroscopy is a promising tool for fast and simple evaluation of wastewater quality, as it delivers spectra that may be correlated to various aggregate wastewater quality parameters, such as Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD). Its application in drainage systems has scarcely been reported and is a step forward in water quality monitoring.Partial Least Squares (PLS) calibration models were developed for TSS and COD prediction, based on UV-Vis spectra. Spectra were acquired in two sites, in-line and off-line. Three approaches for model development were studied. Model evaluation statistics and guidelines were assessed, which allowed grading of the models from unsatisfactory to very good. Most of the developed models were rated very good according to those guidelines. The overall results strongly indicate UV-Vis spectra to be reliable for TSS and COD estimation in sewer systems, despite the rapid variations in hydraulic conditions and water quality.
42 citations
TL;DR: In this article, the authors assess the use of information and intuition in decision-making for sewer pipe replacement decisions and evaluate the success of the intuitive decisions, and identify twenty-one information sources used in intuitive risk analyses considering the following five aspects: pipe collapse, insufficient hydraulic performance, nuisance to citizens and related reputation of the organization, traffic disruption, costs for excavation and costs for surface level reconstruction.
Abstract: Decision-making for sewer asset management is inherently complicated, because of limited data and interaction with multiple actors, making it neither transparent nor reproducible, mostly based on intuition. It is unclear which and how information sources and intuition are used for sewer pipe replacement decisions. Therefore, this study assesses the use of information and intuition in decision-making for replacement decisions. Next to that, the success of the intuitive decisions is addressed. Interviews were conducted at seven municipalities in the Netherlands, combined with analyses of their strategic municipal sewerage plans. Content analysis identified twenty-one information sources used in intuitive risk analyses considering the following five aspects: pipe collapse, insufficient hydraulic performance, nuisance to citizens and related reputation of the organization, traffic disruption, costs for excavation and costs for surface level reconstruction. Given the complex context of sewer asset management a...
35 citations
TL;DR: In this paper, an improved head-discharge relationship is developed and presented in this paper which takes into account two types of demands, volumetric demand and head dependent demand, separately.
Abstract: Most of the currently available models for Water Distribution Network (WDN) hydraulic analysis assume that the nodal demands are independent of nodal heads and fully supplied. However, in practice, discharge of any node is proportional to its head. Considering a head–discharge relationship for each node in the Head Driven Analysis (HDA) method, provides the ability to model WDNs more accurately and realistically. An improved head–discharge relationship is developed and presented in this paper which takes into account two types of demands, volumetric demand and head dependent demand, separately. Most of the HDA-based models use the Newton–Raphson method for simulation. But considering the advantages of the gradient method, e.g. no need for any initial values for nodal heads and robust performance, it is applied in this research through a modified model capable of calculating leakage. The proposed modified model is evaluated using a sample network. Performance of this model is studied in comparison with the...
33 citations
TL;DR: In this article, a case study in Kalmar, Sweden, compared system performance using two design rainfalls, Block rainfalls and Chicago Design Storm (CDS), and selected observed rainfalls.
Abstract: Guidance on what type of rainfall to use when assessing hydraulic capacity of urban drainage systems under climate change is unclear; focus is mainly on what climate factors to use. Based on a case study in Kalmar, Sweden, this paper compares system performance using two design rainfalls, Block rainfalls and Chicago Design Storm (CDS), and selected observed rainfalls, with two methods of addressing future climate: a constant factor and Delta Change (DC) factors that depend on rainfall intensity. The use of CDS rainfalls presents the maximum hydraulic response, whereas Block rainfalls give lower responses but identify critical durations in the system, which may be useful addressing adaptation actions. Observed rainfalls of target return periods gave similar responses to CDS rainfalls, and can be applied with DC factors to address future changes in both intensity and volume. Differences between the two methods indicate a high dependence related to the maximum factors applied on the rainfalls.
TL;DR: In this article, the authors estimated the total length and mass for the wastewater networks of 25 cities in five different countries using a fractal network model that only requires the cities' size and population as input data.
Abstract: Networks for water and wastewater transport represent large capital assets and material stocks within cities. A better understanding of how their material content changes with population and size of the city may help to design networks with lower resource demand and lower construction and maintenance costs. We estimated the total length and mass for the wastewater networks of 25 cities in five different countries using a fractal network model that only requires the cities' size and population as input data. We found that most of the network mass is concentrated in the main trunk lines. The model results showed efficiency of scale: For a catchment area of constant size, both network length and mass per capita would decline if population grew. However, if the population of a city grew while the population density remained constant or decreased (urban sprawl), the per-capita network mass would increase.
TL;DR: In this paper, the distribution of rainfall intensity was analyzed and a circular zone model with exponential shape in all directions has been proposed for describing rain storms, and the velocity of storm zone movement between 2 and 30 km/h was determined.
Abstract: The application of 21 pluviometers over the whole area of Łodź, Poland, enabled an examination of areal distribution of intense rainfalls during 2010–2011. On the basis of collected data the distribution of rainfall intensity was analysed and a circular zone model with exponential shape in all directions has been proposed for describing rain storms. Also, the velocity of storm zone movement between 2 and 30 km/h was determined. Using the SWMM 5.0 software, adapted for non-standard use, runoff from three real catchments and combined storm overflow discharge was examined for selected measured rainfalls. An effect of storm zone range and movement was also studied for the same catchments using model storms. It was confirmed that using data from the city pluviometric network enables significantly better simulation results for CSO overflows to be obtained compared to an option based on a single pluviometric station, especially for large catchments greater than 200 hectares.
TL;DR: In this article, a comprehensive review on relationship and modelling between pipe leaks, materials, and type of failures is presented, and a new relationship is proposed between pipe defects and discharge coefficients, depending on the flow through failures (induced by leaks or intrusions).
Abstract: Most leak management methods are focused on quantifying water losses, directly related to energy and resource waste. In this research work, a comprehensive review on relationship and modelling between pipe leaks, materials, and type of failures is presented. Information necessary to study the main defects of pipe materials has been compiled and the different causes of pipe failures were reviewed and analysed. As a result, types of failures were identified depending on the pipe surrounding, pipe material and mechanisms and stresses that support the pipes. A deep focus of the leak problem is presented, analysing intrusion flows and the related pressure variation using the volume through simple orifices with fixed and variable discharge area: Fixed And Variable Area Discharge (FAVAD theory). Finally, a new relationship is proposed between pipe defects and discharge coefficients, depending on the flow through failures (induced by leaks or intrusions).
TL;DR: In this article, the authors consider the implicit and technocratic hydrosocial contract underpinning the current "big pipes" approach and find that the judgement and advice of water experts is a significant determinant regarding opportunities for realising more resilient water supplies.
Abstract: Today's modern cities' ‘big-pipes in, big-pipes out’ potable water supply approach does not offer society the resilience for adaptation to future climate challenges. One approach towards building resilience would involve cities adopting diverse, alternative water supplies; such as recycled wastewater, greywater and stormwater, within a fit-for-purpose philosophy, incorporating a mix of centralised and decentralised technologies. Globally, modern cities have limited on-ground experience with such complex approaches, despite ad-hoc policy rhetoric to the contrary and multiple technological options. Through considering the implicit and technocratic hydrosocial contract underpinning the current ‘big pipes’ approach, it appears the judgement and advice of ‘water experts’ is a significant determinant regarding opportunities for realising more resilient water supplies. Contrasting primary and secondary survey data from water experts and communities across Australian cities in relation to their receptivity to alt...
TL;DR: In this paper, a methodology is developed to quantify the risk to municipal infrastructure from climate change-related flooding by using a combination of flow/frequency, stage/damage and damage/frequency curves.
Abstract: Extreme rainfall events that are occurring more frequently as an effect of climate change and variability are causing increasing damages to municipal infrastructure. A methodology is developed to quantify the risk to municipal infrastructure from climate change-related flooding. The risk is measured using a combination of flow/frequency, stage/damage and damage/frequency curves. The measure of risk is termed the Risk Index and calculated for each infrastructure element within a municipality. The risk is aggregated and summed by spatial unit and presented in the form of risk tables and maps. The risk index takes into account both quantitative and qualitative information obtained from research and interviews with technical experts. The results from the application of the methodology to a municipality will lead to better policy and informed decision making.
TL;DR: In this paper, a detailed comparison of available advanced grey water treatment for single households and a cost evaluation in view of on-site membrane bioreactor (MBR) systems is presented.
Abstract: Although in recent years new developments for smaller applications have been made, investment costs have decreased and fresh water and sewage fees have increased, it has not been published so far if there are feasible grey water systems for single households with high quality effluent on the market. This paper gives a general overview of grey water treatment systems, a detailed comparison of available advanced grey water treatment for single households and a cost evaluation in view of on-site membrane bioreactor (MBR) systems for single households. The data and information were collected from demo units, publications, manufacturers and suppliers of these systems and were compared with experiences found in research literature. Results show that on-site MBR systems with daily grey water reclamation of more than 500 litres (10 persons) could be cost-effective. For single households the investment is still too high for a payback time of less than 15 years.
TL;DR: In this article, the authors explored the awareness about rooftop rainwater harvesting systems, attitudes towards them and their acceptance among the people of Dehradun, India and found that rooftop rain water harvesting is acceptable to the people but the government needs to provide supportive implementation plans.
Abstract: Water resources, previously considered as free and abundant, are now becoming scarce, which will potentially affect human welfare. Urban areas experience increased water demands directly proportional to the rate of urbanisation, causing a stress on water sources. Rooftop rainwater harvesting in cities and towns is an effective tool for recharging depleting aquifers and for meeting the demand for water. Indian national and state governments have framed rules and policies supporting installation of rainwater harvesting structures, but implementation of these requires the acceptance and willingness of people. The present study explores the awareness about rooftop rainwater harvesting systems, attitudes towards them and their acceptance among the people of Dehradun, India. The results indicate that rooftop rainwater harvesting is acceptable to the people but the government needs to provide supportive implementation plans.
TL;DR: Numerical experiments on a semi-virtual asset stock have been conducted to answer two main questions: how to establish a list of the most informative factors and whether it is better to have data imprecision instead of data incompleteness in a utility database.
Abstract: One key aspect of sewer inspection programs is the prediction of sewer condition. Despite the development of deterioration models, the influence of available data on models' predictive power has not been studied in depth. In this article, numerical experiments on a semi-virtual asset stock have been conducted to answer two main questions: how to establish a list of the most informative factors and whether it is better to have data imprecision instead of data incompleteness in a utility database. Two approaches for establishing a list of the most informative factors are compared. The results show a statistical analysis (a priori analysis) can predict the impact of available data on inspection program efficiency (a posteriori analysis). This can be used to plan data acquisition programs. Finally, we show that using the notion of “district” (data imprecision) can provide efficient results when the most informative factor “age” is not available (data incompleteness).
TL;DR: In this article, the authors present a procedure for the generation and spatial-temporal aggregation of synthetic water demand time series which reproduce the main statistics -mean, variance and (spatial and temporal) covariance - of the corresponding observed series.
Abstract: This paper presents a procedure for the generation and spatial-temporal aggregation of synthetic water demand time series which reproduce the main statistics - mean, variance and (spatial and temporal) covariance - of the corresponding observed series. Starting from observed historical time series taken at low levels of temporal aggregation (e.g., one minute) and relating to individual users, the procedure enables a) the generation of synthetic water demand time series for every individual user with a time step of one minute, b) the temporal aggregation of these synthetic series in order to obtain synthetic water demand time series with a time step, for example, of one hour, and which are such as to reproduce the hourly mean, variance and temporal covariances of the corresponding temporally aggregated historical time series, and c) the spatial aggregation of the synthetic hourly water demand time series of every user in order to generate a synthetic water demand time series that is representative of the e...
TL;DR: In this paper, the problem of water distribution system (WDS) re-design is formulated as a multi-objective optimisation problem and three objectives are as follows: (1) minimisation of total (re)design cost, (2) maximisation of the WDS resilience and, (3) minimization of GHGs emissions.
Abstract: Water distribution systems (WDSs) construction, operation and disposal processes contribute to undesirable greenhouse gas (GHG) emissions. GHG concentration in the atmosphere is strongly associated with global warming and climate change. In order to meet the consequent challenge of limiting GHG emissions, the problem of WDS (re)design is formulated here as a multi-objective optimisation problem. The three objectives are as follows: (1) minimisation of total (re)design cost, (2) maximisation of the WDS resilience and, (3) minimisation of GHGs emissions. In addition to the frequently considered conventional (re)design intervention options (new pipes, pipe duplication or replacement, addition of pumps, tanks, etc.), various water demand management interventions (e.g. water efficient appliances and domestic Rainwater Harvesting Systems) are considered here too. A number of different rainwater tank sizes and water saving appliances provided to different parts of the households have been evaluated. This methodo...
TL;DR: In this article, the authors present a conceptual approach to the successive introduction of a continuous water distribution system based on existing systems originally designed for continuous distribution but currently run in the intermittent mode.
Abstract: Centralised water distribution systems in developing countries currently are operated intermittently to a very large extent. As a consequence of the numerous negative impacts associated with intermittent water distribution, functioning water supplies in the long run absolutely require the introduction of a continuous mode of water distribution. This article presents a conceptual approach to the successive introduction of a continuous water distribution. The approach is based on existing systems originally designed for continuous distribution but currently run in the intermittent mode. The focus is on the difficulties in planning and implementing the complex processes of database organisation, restructuring and changing the mode of operation, which are harmonised in a comprehensive process. The approach is explained for the case of the water distribution system in Beni Abbes, Algeria.
TL;DR: In this paper, the authors explored the potential for real-time urban flood forecasting based on literature and the results from an online worldwide survey with 176 participants and found that a significant number of the participants have used some kind of data and that a possible explanation for so few cases is that urban flood managers or modellers may not be aware they have the means to make a pluvial flood forecast.
Abstract: This paper explores the potential for real-time urban flood forecasting based on literature and the results from an online worldwide survey with 176 participants. The survey investigated the use of data in urban flood management as well as the perceived challenges in data acquisition and its principal constraints in urban flood modelling. It was originally assumed that the lack of real-time urban flood forecasting systems is related to the lack of relevant data. Contrary to this assumption, the study found that a significant number of the participants have used some kind of data and that a possible explanation for so few cases is that urban flood managers or modellers (practitioners) may not be aware they have the means to make a pluvial flood forecast. This paper highlights that urban flood practitioners can make a flood forecast with the resources currently available.
TL;DR: In this paper, a high density polyethylene (HDPE) pipeline for transient conditions is presented and discussed, where the viscoelastic transient solver developed by Covas et al. (2005) was used to carry out numerical simulations of experimental tests.
Abstract: New experimental results obtained from a high density polyethylene (HDPE) pipeline for transient conditions are presented and discussed. Transient pressure data at different pipe sections were collected. Peculiar features were observed, which are typical of viscoelastic pipes, in particular, a significant damping of extreme pressures was observed in comparison to what is typically obtained for metal pipes. Physical constraints of the pipe are important to describe some vibrations observed in the system. The viscoelastic transient solver developed by Covas et al. (2005) was used to carry out numerical simulations of experimental tests. The comparison of numerical results with experimental data has shown that the viscoelastic model accurately predicts observed transient pressures. Additional considerations are carried out about the calibrated creep function for this test case in comparison with the ones obtained in previous researches.
TL;DR: In this article, the authors analyzed the interconnected nature of these barriers using a combination of interpretive structural modelling and systems thinking methods, and found that barriers not only reinforce each other, but also create persistent self-reinforcing effects within a barrier interaction network.
Abstract: The prevalence of barriers to the implementation of alternative and more integrated approaches to urban water management has been observed by many researchers and managers. This study analyses the interconnected nature of these barriers using a combination of interpretive structural modelling and systems thinking methods. Based on empirical data from an urban case study catchment this study shows that barriers not only reinforce each other, but also create persistent self-reinforcing effects within a barrier interaction network. Evidence of feedback structures was primarily found in the institutional and logistical management areas. These systemic feedback structures create resistance to the implementation of alternative urban water management strategies resulting in the status quo. Knowledge of barrier interactions provides a rational basis for targeted and prioritized management interventions.
TL;DR: In this paper, risk perceptions of water practitioners and how they affect practitioner receptivity to future modes of urban water supply are poorly understood, and a study characterises risk perceptions and attitudes of Australian urban water practitioners towards alternative water systems and uses a receptivity framework to suggest how receptive practitioners are to these systems.
Abstract: Transition to a water-cycle city, a sustainable urban water management future, requires the implementation of centralised and decentralised systems to augment potable water supply, protect waterways and enhance urban liveability. Risk is simultaneously driving and impeding this transition. However, risk perceptions of water practitioners and how they affect practitioner receptivity to future modes of urban water supply are poorly understood. This study characterises risk perceptions and attitudes of Australian urban water practitioners towards alternative water systems and uses a receptivity framework to suggest how receptive practitioners are to these systems. Differences between cities are identified, suggesting how familiarity might influence receptivity. These results can inform strategies to enhance receptivity, including improved communication within the water industry and beyond with its various stakeholders, improved cost-projection frameworks to provide a quantitative metric of the benefits of su...
TL;DR: In this paper, two types of dual drainage models were set up to assess urban flooding for a study area in Germany: (1) a static model based on a conventional method in Germany; the overflow volumes of the manholes are gained by the sewer solver HYSTEM-EXTRAN.
Abstract: Two types of dual drainage models were set up to assess urban flooding for a study area in Germany: (1) a static model based on a conventional method in Germany; the overflow volumes of the manholes are gained by the sewer solver HYSTEM-EXTRAN. Using these water volumes and geographic information system (GIS) tools, an overland flow network, composed of flow paths and accumulated water in sinks, is produced, (2) a HYSTEM-EXTRAN 2D model; a two-dimensional (2D) overland flow module is coupled bi-directionally with HYSTEM-EXTRAN. The overland flow and the flow in the sewer system are simulated alternately.Both models were supplied with a synthetic design rainfall and 25 extreme storms. After comparing the models and the results, a practical approach to assess urban flooding is proposed. In this approach the 2D model will compute the depth, extent, and propagation of floods only in the prone areas specified by the static model.
TL;DR: In this paper, the results of sediment size characteristics and deposition analysis on 24 sediment samples from urban concrete drains in Kuching City were highlighted and compared with the results from surrounding urban towns outside KL and Penang.
Abstract: This paper highlights the results of sediment size characteristics and deposition analysis on 24 sediment samples from urban concrete drains in Kuching City. Further sampling from surrounding urban towns outside Kuching City and Penang were done for comparison. Samples were collected randomly from three land-use types (residential, commercial and industrial). Sieve analysis results had shown that most of the total samples collected (51 out of 57) were predominantly sand, followed by gravel; while silt and clay were the minor components. Unimodal characteristics were observed in 46 samples while 11 samples showed bimodal characteristics. Of the total 46 unimodal samples, 39 showed non-uniform distribution with tendency to skew to the right. Due to this, the mode grain size with characteristic diameter d45 is suggested as a much better representative size than the conventional median size d50. Factors affecting sediment deposition characteristics in urban drains are also discussed.
TL;DR: In this article, a semi-distributed hydrological model has been developed for determining runoff in an ungauged peri-urban catchment of north east India.
Abstract: A semi-distributed hydrological model has been developed in this study for determining runoff in an ungauged peri-urban catchment of north east India. In the absence of discharge data, the study has focused on how to improve the accuracy of runoff prediction based on imperviousness determination by spatial method. The imperviousness is defined in terms of total impervious area (TIA) and effective impervious area (EIA). The study highlights misclassification as one of the factors causing error in imperviousness determination. It is recommended that integrating GIS data with high resolution satellite imagery can be an effective solution to minimise misclassification. The predicted peak runoff was 33.4% larger when GIS based imperviousness is employed in the model. The peak runoff was 72.2% more in 2006 as compared to 1980 due to an increase in imperviousness, which is attributed to urbanisation.
TL;DR: In this paper, the main landscaping typologies used on suburban properties were identified and characterised: ornamental, vegetable, lawn and tree, and a multinomial logistic regression analysis revealed how each landscaping pattern is associated with particular sociodemographic characteristics of the households (e.g., age, size, unemployment, length of residency).
Abstract: The act of watering a garden greatly increases domestic water consumption in residential areas. This issue has caused local governments and managers to become concerned over how homeowners shape and maintain their gardens. This subject is critical along the Mediterranean coast, where residential urban sprawl has expanded over the last few decades and water resources are scarce. Suburban residents from the Girona region of Catalonia, Spain were surveyed to determine the main landscaping typologies used on suburban properties. Four garden typologies were identified and characterised: ornamental, vegetable, lawn and tree. Furthermore, a multinomial logistic regression analysis revealed how each landscaping pattern is associated with particular sociodemographic characteristics of the households (e.g., age, size, unemployment, length of residency). Management guidelines for water users, real estate companies and local governments are provided in the conclusions, focused on raising awareness and cooperation.