113 results found
Pina RD, Ochoa Rodriguez S, Simões NE, et al., 2016, Semi- vs. Fully-Distributed Urban Stormwater Models: Model Set Up and Comparison with Two Real Case Studies, Water, Vol: 8, ISSN: 2073-4441
Urban stormwater models can be semi-distributed (SD) or fully distributed (FD). SD models are based on subcatchment units with various land use types, where rainfall is applied and runoff volumes are estimated and routed. FD models are based on the two dimensional (2D) discretization of the overland surface, which has a finer resolution with each grid-cell representing one land use type, where runoff volumes are estimated and directly routed by the 2D overland flow module. While SD models have been commonly applied in urban stormwater modeling, FD models are generally more detailed and theoretically more realistic. This paper presents a comparison between SD and FD models using two case studies in Coimbra (Portugal) and London (UK). To enable direct comparison between SD and FD setups, a model-building process is proposed and a novel sewer inlet representation is applied. SD and FD modeling results are compared against observed records in sewers and photographic records of flood events. The results suggest that FD models are more sensitive to surface storage parameters and require higher detail of the sewer network representation.
Leitao JP, Prodanovic D, Maksimovic C, 2016, Improving merge methods for grid-based digital elevation models, Computers and Geosciences, Vol: 88, Pages: 115-131, ISSN: 0098-3004
Digital Elevation Models (DEMs) are used to represent the terrain in applications such as, for example, overland flow modelling or viewshed analysis. DEMs generated from digitising contour lines or obtained by LiDAR or satellite data are now widely available. However, in some cases, the area of study is covered by more than one of the available elevation data sets. In these cases the relevant DEMs may need to be merged. The merged DEM must retain the most accurate elevation information available while generating consistent slopes and aspects. In this paper we present a thorough analysis of three conventional grid-based DEM merging methods that are available in commercial GIS software. These methods are evaluated for their applicability in merging DEMs and, based on evaluation results, a method for improving the merging of grid-based DEMs is proposed. DEMs generated by the proposed method, called MBlend, showed significant improvements when compared to DEMs produced by the three conventional methods in terms of elevation, slope and aspect accuracy, ensuring also smooth elevation transitions between the original DEMs. The results produced by the improved method are highly relevant different applications in terrain analysis, e.g., visibility, or spotting irregularities in landforms and for modelling terrain phenomena, such as overland flow.
Zhang T, Feng P, Maksimovic C, et al., 2015, Application of a Three-Dimensional Unstructured-Mesh Finite-Element Flooding Model and Comparison with Two-Dimensional Approaches, Water Resources Management, Vol: 30, Pages: 823-841, ISSN: 1573-1650
Urban flood modelling plays a key role in assessment of flood risk in urbanareas by providing detailed information of the flooding process (e.g. location, depth andvelocity of flooding). Accurate modelling results are the basis of reliable flood risk evaluation.In this paper, modelling of a flood event in a densely urbanized area within thecity of Glasgow is presented. Modelling is performed using a new three-dimensional (3D)flooding model, which is an unstructured mesh, finite element model that solves the NavierStokesequations, and developed based on Fluidity. The terrain data considered comesfrom a 2 m Light Detection and Ranging (LiDAR) Digital Terrain Model (DTM) andaerial imagery. The model is validated with flood inundation area and flow features, andsensitivity analyses are conducted to identify the mesh resolution required for accuracypurposes and the effect of the uncertainty in the inflow discharge. Good agreement hasbeen achieved when comparing the results with those published in other 2D shallow watermodels in ponded areas. However, larger vertical velocity (> 0.2 m/s) and larger differencesbetween the 3D and 2D models can be observed in areas with greater topographicgradients (> 3 %). Finally, performance of the proposed 3D flooding model has been analysed.Through the modelling of a real flooding event this paper helps illustrate the case that 3D modelling techniques are promising to improve accuracy and obtain more detailedinformation related to urban flooding dynamics, which is useful in urban flood controlplanning and risk management. To the best of our knowledge, this is the first paper toapply a 3D unstructured mesh finite-element model (FEM model) to a real urban floodingevent. It highlights some of the differences between the 3D and 2D urban flood modellingresults.
Barbir J, Dorado J, Fernandez-Quintanilla C, et al., 2014, Wild rocket - effect of water deficit on growth, flowering, and attractiveness to pollinators, ACTA AGRICULTURAE SCANDINAVICA SECTION B-SOIL AND PLANT SCIENCE, Vol: 64, Pages: 482-492, ISSN: 0906-4710
Lari KS, van Reeuwijk M, Maksimovic C, 2013, The role of geometry in rough wall turbulent mass transfer (vol 49, pg 1191, 2013), HEAT AND MASS TRANSFER, Vol: 49, Pages: 1523-1523, ISSN: 0947-7411
Sookhak Lari K, Reeuwijk M, Maksimović Č, 2013, The role of geometry in rough wall turbulent mass transfer, Heat and Mass Transfer, Vol: 49, Pages: 1191-1203, ISSN: 0947-7411
Pablo Rodriguez J, McIntyre N, Diaz-Granados M, et al., 2013, Generating time-series of dry weather loads to sewers, ENVIRONMENTAL MODELLING & SOFTWARE, Vol: 43, Pages: 133-143, ISSN: 1364-8152
Pablo Rodriguez J, McIntyre N, Diaz-Granados M, et al., 2013, Monitoring and modelling to support wastewater system management in developing mega-cities., SCIENCE OF THE TOTAL ENVIRONMENT, Vol: 445, Pages: 79-93, ISSN: 0048-9697
Manz BJ, Pablo Rodriguez J, Maksimovic C, et al., 2013, Impact of rainfall temporal resolution on urban water quality modelling performance and uncertainties, WATER SCIENCE AND TECHNOLOGY, Vol: 68, Pages: 68-75, ISSN: 0273-1223
Leitao JP, Prodanovic D, Boonya-aroonnet S, et al., 2013, Enhanced DEM-based flow path delineation methods for urban flood modelling, JOURNAL OF HYDROINFORMATICS, Vol: 15, Pages: 568-579, ISSN: 1464-7141
Nie L, Roald LA, Mellegard S, et al., 2013, Flood risk management in a cold climate - experience in Norway, 5th International Conference on Flood Management (ICFM5), Publisher: INT ASSOC HYDROLOGICAL SCIENCES, Pages: 198-+, ISSN: 0144-7815
Rozos E, Makropoulos C, Maksimovic C, 2013, Rethinking urban areas: an example of an integrated blue-green approach, WATER SCIENCE AND TECHNOLOGY-WATER SUPPLY, Vol: 13, Pages: 1534-1542, ISSN: 1606-9749
Rodríguez JP, McIntyre N, Díaz-Granados M, et al., 2012, A semi-distributed modelling approach to support wastewater system management in large Urban areas, Pages: 3143-3151
Models that represent the integrated urban drainage system are needed to holistically assess and manage its performance. Furthermore such models should ideally be spatially distributed to support evaluation of individual components and their role within the system. However, due to data constraints and computational costs, high resolution models of the sewer system are unlikely to be applicable when dealing with large scale and complex systems. This work assesses the value of a relatively simple semi-distributed grey-box modelling approach, which, in comparison with a fully distributed approach, decreases supporting data requirements but still aims to provide a reasonable spatial representation of the sewer system and its temporal variability, thus enabling integrated assessment. New methods for characterising uncertainty in flow and pollution load inputs during dry weather conditions are also used. A large urban catchment in Bogotá (Colombia) is used as a case study. Modelled and observed flow and pollutant concentration data demonstrated high apparently random variability of dry weather flow profiles within the sewer system. Against this variability, the effects of in-sewer processes were not identifiable except where backwaters caused particularly high retention times.
Rodríguez J-P, McIntyre N, Díaz-Granados2 M, et al., 2012, A database and model to support proactive management of sediment-related sewer blockages
Due to increasing customer and political pressures, and more stringent environmental regulations, sediment and other blockage issues are now a high priority when assessing sewer system operational performance. Blockages caused by sediment deposits reduce sewer system reliability and demand remedial action at considerable operational cost. Consequently, procedures are required for identifying which parts of the sewer system are in most need of proactive removal of sediments. This paper presents an exceptionally long (7.5 years) and spatially detailed (9,658 grid squares – 0.03 km2 each – covering a population of nearly 7.5 million) data set obtained from a customer complaints database in Bogotá (Colombia). The sediment-related blockage data are modelled using homogeneous and non-homogeneous Poisson process models. In most of the analysed areas the inter-arrival time between blockages can be represented by the homogeneous process, but there are a considerable number of areas (up to 34%) for which there is strong evidence of non-stationarity. In most of these cases, the mean blockage rate increases over time, signifying a continual deterioration of the system despite repairs, this being particularly marked for pipe and gully pot related blockages. The physical properties of the system (mean pipe slope, diameter and pipe length) have a clear but weak influence on observed blockage rates. The Bogotá case study illustrates the potential value of customer complaints databases and formal analysis frameworks for proactive sewerage maintenance scheduling in large cities.
Gires A, Onof C, Maksimovic C, et al., 2012, Quantifying the impact of small scale unmeasured rainfall variability on urban runoff through multifractal downscaling: A case study, JOURNAL OF HYDROLOGY, Vol: 442, Pages: 117-128, ISSN: 0022-1694
Gires A, Schertzer D, Tchiguirinskaia I, et al., 2012, Impact of small-scale rainfall uncertainty on urban discharge forecasts, WEATHER RADAR AND HYDROLOGY, Vol: 351, Pages: 400-+, ISSN: 0144-7815
Wang L, Ochoa-Rodriguez S, Simoes N, et al., 2012, Radar-raingauge data combination techniques: a revision and analysis of their suitability for urban hydrology
Evers M, Jonoski A, Maksimović Č, et al., 2012, Collaborative modelling for active involvement of stakeholders in urban flood risk management, Natural Hazards and Earth System Science, Vol: 12, Pages: 2821-2842, ISSN: 1684-9981
Gires A, Schertzer D, Tchiguirinskaia I, et al., 2011, Impact of unmeasured rainfall variability on urban discharge: a case study in a multifractal framework, HOUILLE BLANCHE-REVUE INTERNATIONALE DE L EAU, Pages: 37-42, ISSN: 0018-6368
Chen DC, Maksimovic C, Voulvoulis N, 2011, Institutional capacity and policy options for integrated urban water management: a Singapore case study, Water Policy, Vol: 13, Pages: 53-68, ISSN: 1366-7017
Singapore is an exemplary model of integrated water management, according to the World Health Organization, and its experiences can be shared with others. Water security is not just the government's responsibility but has become everyone's business. Singapore has been selected as a case study for integrated urban water management (IUWM), and the methodologies used in Singapore, a developed city state, may be applicable elsewhere. An integrated regulatory framework, sound policies to control and implement programmes, public-private partnership in water services delivery, and stakeholder participation at all levels are necessary to make integrated water resource management successful. This paper demonstrates how Singapore has successfully turned its vulnerability with regard to water into a strength. Singapore can achieve greater sustainability if it promotes rooftop rainwater harvesting as a decentralized, dual-mode water supply system for non-potable use.
Visessri S, McIntyre N, Maksimovic C, 2011, Water availability assessment in data scarce catchments: case study of the Ping River basin, Thailand, 25th General Assembly of the International Union of Geodesy and Geophysics, Publisher: INT ASSOC HYDROLOGICAL SCIENCES, Pages: 259-264, ISSN: 0144-7815
Visessri S, McIntyre N, Maksimovic C, 2011, The impact of temporal and spatial resolution on developing risk maps: case study of the Tubma basin, Thailand, 25th General Assembly of the International Union of Geodesy and Geophysics, Publisher: INT ASSOC HYDROLOGICAL SCIENCES, Pages: 175-180, ISSN: 0144-7815
Wang L, Simoes NE, Rico-Ramirez M, et al., 2011, Radar-based pluvial flood forecasting over urban areas: Redbridge case study, Exeter, UK, International Symposium on Weather Radar and Hydrology (WRaH)
Cortes-Arevalo J, Almoradie A, Jonoski A, et al., 2011, Flood risk management via collaborative modelling, Exeter, UK, 11th International Conference on Computing and Control for the Water Industry, Urban Water Management: Challenges and Opportunities
Sookhak Lari K, van Reeuwijk M, Maksimovic C, 2011, Combined bulk and wall reactions in turbulent pipe flow: decay coefficients and concentration profiles, J HYDROINF, Vol: 13, Pages: 324-333
Idornigie E, Templeton MR, Maksimovic C, et al., 2010, The impact of variable hydraulic operation of water distribution networks on disinfection by-product concentrations, Urban Water Journal, Vol: 7, Pages: 301-307, ISSN: 1573-062X
This study assessed the magnitude of variations in the concentrations of disinfection by-products, specifically trihalomethanes and haloacetic acids, which occur in two UK water distribution networks of different sizes due to changes in the hydraulic operation of the networks. These operational changes included varying the fill levels of water storage tanks and pumping conditions within the network. This was investigated through modelling which combined a conventional distribution network flow model (EPANET) with previously developed models for disinfection by-product formation, and using network information obtained from water company partners. The modelling demonstrated that there is the potential for significant variations in disinfection by-product concentrations, up to a 40% change in some simulations, due to what may be considered routine variability in the hydraulic operation of the network. Smaller networks may be especially susceptible to these variations. These findings may influence how water companies plan disinfection by-product monitoring programmes for regulatory reporting.
Sookhak Lari K, van Reeuwijk M, Maksimovic C, 2010, Simplified Numerical and Analytical Approach for Solutes in Turbulent Flow Reacting with Smooth Pipe Walls, J HYDR ENG (ASCE)
Sookhak Lari K, Van Reeuwijk M, Maksimovic C, 2010, A study of wall demand in turbulent pipe flows, Sheffield, Proc. Computing and Control in the Water Industry (CCWI)
Simoes NE, Leitao JP, Maksimovic C, et al., 2010, Sensitivity analysis of surface runoff generation in urban flood forecasting, WATER SCIENCE AND TECHNOLOGY, Vol: 61, Pages: 2595-2601, ISSN: 0273-1223
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