Search

The paper proposes a spreadsheet-based model to simulate the hydrological response of a pilot installation of modular tray-based blue roof (BR). The BR is installed on the roof terrace of a building in the Campus of the University of Catania (Italy). The paper firstly describes the results of preliminary field experiments on the pilot aimed at evaluating hydrological parameters used in the model, i.e. the runoff coefficient and the initial abstraction of the terrace, and the evaporation from the BR. Then, the model was applied to 26 precipitation events recorded in the period from 2018 to 2020. Results of the application show a good ability of the model to reproduce the hydrological behaviour of the BR during precipitation events. Finally, the paper discusses limitations of the results obtained and potential for model improvement. [ABSTRACT FROM AUTHOR]

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)maynot 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. [ABSTRACT FROM AUTHOR]

Investigation of various phenomena occurring in sewer systems is critical for increasing the sustainability of such systems. Such investigations also includes gross solids (GS) transport. GS transport may be affected by reduction of flows resulting from population decrease and/or reduced domestic water consumption. The present paper reports on the development of a model for describing GS velocity as a function of wastewater flow characteristics. The model was calibrated and validated with field experiments, in which two methods for GS tracking in sewers were developed, using small light sticks tracked by computerized light detector, and RFID based tracking. The model is integrated in a simulator which allows a description of the movement of individual GS through sewer systems. The developed model may assist in analysing existing sewer systems that are subject to changes in their input flows and prevent undesired failures (e.g. sedimentations, blockages, toxic gases) or in designing new systems. [ABSTRACT FROM AUTHOR]

The design of alternative urban water supply interventions for a community located in a low-income country requires detailed and precise knowledge of the nature, frequency and intensity of various characteristic water end-uses in the community. Without the availability of this characteristic water use information, high resolution metering experiments are the usually preferred methods to measure the water use volumes. However, in the developing world, these high resolution experiments are not an available option. Leaving the imprecise household interviewing process of data collection as the only option. This paper presents a novel methodology that improves and expands on the socially collected water uses data, through the use of a stochastic modelling process of the water use volumes to estimate the total monthly water use of the community. The methodology not only improves the estimates of water use volumes but also provides a mathematical modelling description of the household water uses in the community. [ABSTRACT FROM AUTHOR]

Using a case study on the Lambro River and the Stream Bevera, this paper compares the use of dynamic modelling with the “normative criteria” to evaluate the effects of Combined Sewer Overflows (CSOs). The normative criteria is the method currently used in Italy to design first flush water tanks to reduce the pollutant discharges. The dynamic modelling technique compares the natural river conditions and the conditions in the river when a CSO occurs. This study finds that the current law, which is based on an effluent standard approach, can significantly underestimate the size of the CSO storage tanks needed to prevent pollution. An alternative is to change the law to use a stream standard approach and to require the CSO tanks to be sized based on the volume and concentration of the pollutants at the CSO. By using a dynamic model of the river, it was found possible to provide a more accurate estimate of the size of the CSO storage tanks required to prevent pollution. Furthermore the paper finds that without a model, it is almost impossible to evaluate the effect of CSOs and changes to the size of the CSO storage tanks. [ABSTRACT FROM AUTHOR]

Global flood management is a major issue for most cities which have to deal with worsening factors such as climate change and fast urban growth. Computer models have been used to model and understand urban flooding on a local scale in cities (25–50 km2). It has been practically impossible to model bigger cities in one go in sufficiently high resolution due to the heavy computations involved. The present paper describes a new modelling approach for urban flooding which allows modelling on large city scale (1000 km2) while keeping sufficient resolution, e.g. 5 m or 10 m grid. The multicell approach is applied for the city of Beijing for July 21st, 2012 flood event. Model results are compared to testimonials from the 2012 event. Comparison to traditional 2D urban flood computations shows that the multicell approach is much faster than standard detailed models while keeping a suitable level of precision. [ABSTRACT FROM AUTHOR]

In spite of considerable uncertainty reported on the impact of Combined Sewer Overflows (CSO), it is generally acknowledged to not be negligible. Not surprisingly CSO impact is considered – although indirectly – in driving European legislations regarding the wastewater pollution and treatment. Still, when looking at impact reduction, policy makers tend to resort rather to static solutions such as disconnection or the building of storage tanks. On the other hand they often seem to be put off by dynamic measures such as Real Time Control (RTC) of sewage systems because of its perceived complexity. This paper describes a cost-benefit analysis of several static and dynamic solutions to mitigate CSO impact, based on the case-study of the Kessel-Lo catchment in Flanders/Belgium. RTC turned out to be not only the most cost efficient measure for CSO impact mitigation but also the solution offering the most flexibility for further system upgrade. [ABSTRACT FROM PUBLISHER]

Historically, computing power and software limitations necessitated that only the most significant features of the distribution system are represented. In recent years, advances in hardware and software technologies have provided the ability to include all the pipes in the distribution system. An all-pipes hydraulic model with 157,000 pipes was developed at the Las Vegas Valley Water District (District) utilising a one-to-one relationship between model features and GIS features. Calibration of such large models poses challenges in terms of collecting and handling large amounts of data from various sources, including SCADA, GIS and an enterprise database. This paper presents data integration, processes and tools developed at the District for calibration of a large all-pipes model. [ABSTRACT FROM AUTHOR]

Hydraulic water distribution system (WDS) simulation models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Similarly, water quality models that work in concert with hydraulic models are now commonly used to simulate the dispersion of and changes in water quality in a water distribution network. As with all mathematical models, WDS model parameters (hydraulic and water quality) require calibration before useful results may be obtained. Nowadays, automated calibration procedures are widely available for hydraulic models, but less so for water quality models. Even when they are available as commercial software, the use of these advanced calibration tools in engineering practice has been limited. This paper provides a review of model calibration approaches and considers future challenges and directions. [ABSTRACT FROM AUTHOR]

In many tropical island settings in the world and as a result of human activities and tropical weather conditions, urban areas have been vulnerable to special kinds of hazards. The most common and the most widely experienced hazard events for these localities are tropical cyclones and accompanying storm surges, flash floods and landslides. Such events can cause serious damages to the drainage systems, roads, properties, receiving environment and even the loss of human lives. Given the threats of climate change, such natural disasters are likely to strengthen this trend in the coming years. In many situations, it is the population living in low-lying urban areas that are most exposed to these disasters. From this, it follows that the scientific and professional communities have a responsibility to evolve better stormwater management approaches directed to minimizing hazard risks owing to urban flooding, even while addressing different climatic conditions. Although, the physics, chemistry and biology of processes related to water are universal, some of the processes and implementation of measures to manage water vary in terms of the climate conditions, geographical location, availability of resources and local culture. In tropical island conditions, where flash floods occur frequently, alongside the obvious structural measures, effective non-structural measures, such as better hazard mitigation and prevention, improved preparedness and introduction of warning systems, well organised pre-emptive action and emergency response activities, have to be coupled together in order to minimize damages. Furthermore, as the management of urban flooding is an emerging subject, it is necessary to understand that such a topic needs to be treated holistically, and so in a multi-disciplinary manner. This implies that the public, town planners, economists, lawyers, emergency services, and many other groups need to be involved, along with the engineers, surveyors and contractors, in developing strategic plans for hazard reduction, operational management and post-event recovery. Thus the stakeholders have to be involved in the decision-making processes (e.g., Abbot 2007, available at www.eiil.net). The present paper describes an integrated stormwater management approach oriented towards the small islands in tropical climates which continuously tend to suffer from flash floods. The approach outlined here draws on the work experiences gained in the Caribbean. [ABSTRACT FROM AUTHOR]