Imperial College London

DrChristianOnof

Faculty of EngineeringDepartment of Civil and Environmental Engineering

Reader in Stochastic Environmental Systems
 
 
 
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Contact

 

c.onof

 
 
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Location

 

410Skempton BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

170 results found

Onof C, Arnbjerg-Nielsen K, 2009, Quantification of anticipated future changes in high resolution design rainfall for urban areas, 7th International Workshop on Precipitation in Urban Areas, Publisher: ELSEVIER SCIENCE INC, Pages: 350-363, ISSN: 0169-8095

Conference paper

Chun KP, Wheater HS, Onof CJ, 2009, Streamflow estimation for six UK catchments under future climate scenarios, HYDROLOGY RESEARCH, Vol: 40, Pages: 96-112, ISSN: 0029-1277

Journal article

Segond M-L, Onof C, 2009, Modelling of space-time rainfall for three UK regions, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-WATER MANAGEMENT, Vol: 162, Pages: 147-158, ISSN: 1741-7589

Journal article

Chun KP, 2009, Streamflow estimation for six UK Catchments under future climate scenarios, Hydrology Research

Journal article

Marsh L, Onof C, 2008, Introduction to the special issue ''Perspectives on Social Cognition'', COGNITIVE SYSTEMS RESEARCH, Vol: 9, Pages: 1-4, ISSN: 1389-0417

Journal article

Marsh L, Onof C, 2008, Stigmergic epistemology, stigmergic cognition, COGNITIVE SYSTEMS RESEARCH, Vol: 9, Pages: 136-149, ISSN: 2214-4366

Journal article

Onof C, 2008, Property dualism, epistemic normativity and the limits of naturalism, PHILOSOPHY AND PHENOMENOLOGICAL RESEARCH, Vol: 76, Pages: 60-85, ISSN: 0031-8205

Journal article

Segond M-L, Wheater HS, Onof C, 2007, The significance of spatial rainfall representation for flood runoff estimation: A numerical evaluation based on the Lee catchment, UK, JOURNAL OF HYDROLOGY, Vol: 347, Pages: 116-131, ISSN: 0022-1694

Journal article

Cowpertwait P, Isham V, Onof C, 2007, Point process models of rainfall: developments for fine-scale structure, PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 463, Pages: 2569-2587, ISSN: 1364-5021

Journal article

Segond M-L, Neokleous N, Makropoulos C, Onof C, Maksimovic Cet al., 2007, Simulation and spatio-temporal disaggregation of multi-site rainfall data for urban drainage applications, HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES, Vol: 52, Pages: 917-935, ISSN: 0262-6667

Journal article

Butler D, McEntee B, Onof C, Hagger Aet al., 2007, Sewer storage tank performance under climate change, WATER SCIENCE AND TECHNOLOGY, Vol: 56, Pages: 29-35, ISSN: 0273-1223

Journal article

Segond ML, Onof C, Wheater HS, 2006, Spatial-temporal disaggregation of daily rainfall from a generalized linear model, J HYDROL, Vol: 331, Pages: 674-689, ISSN: 0022-1694

This paper describes a methodology for continuous simulation of spatially-distributed hourly rainfall, based on observed data from a daily raingauge network. Generalized linear models (GLMs), which can represent the spatial and temporal non-stationarities of multi-site daily rainfall (Chandler, R.E., Wheater, H.S., 2002. Analysis of rainfall variability using generalised linear models: a case study from the west of Ireland. Water Resources Research, 38 (10), 1192. doi:10.1029/2001WR000906), are combined with a single-site disaggregation model based on Poisson cluster processes (Koutsoyiannis, D., Onof, C., 2001. Rainfall disaggregation using adjusting procedures on a Poisson cluster model. Journal of Hydrology 246, 109-122). The resulting sub-daily temporal profile is then applied linearly to all sites over the catchment to reproduce the spatially-varying daily totals. The method is tested for the River Lee catchment, K, a tributary of the Thames covering an area of 1400 km(2). Twenty simulations of 12 years of hourly rainfall are generated at 20 sites and compared with the historical series. The proposed model preserves most standard statistics but has some limitations in the representation of extreme rainfall and the correlation structure. The method can be extended to sites within the modelled region not used in the model, calibration. (c) 2006 Elsevier B.V. All. rights reserved.

Journal article

Onof CJ, 2006, Understanding phenomenal consciousness, PHILOSOPHICAL PSYCHOLOGY, Vol: 19, Pages: 543-547, ISSN: 0951-5089

Journal article

Lekkas DF, Onof C, 2006, Introducing the variation of advective time delay (ATD) to Transfer Function models, ENVIRONMENTAL MODELLING & SOFTWARE, Vol: 21, Pages: 1180-1189, ISSN: 1364-8152

Journal article

Wheater HS, Chandler RE, Onof CJ, Isham VS, Bellone E, Yang C, Lekkas D, Lourmas G, Segond MLet al., 2005, Spatial-temporal rainfall modelling for flood risk estimation, STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT, Vol: 19, Pages: 403-416, ISSN: 1436-3240

Journal article

Onof C, Townend J, Kee R, 2005, Comparison of two hourly to 5-min rainfall disaggregators, Atmospheric Research, Vol: 77, Pages: 176-187, ISSN: 0169-8095

Journal article

Lekkas DF, Onof C, 2005, Improved flow forecasting using artificial neural networks, 9th International Conference on Environmental Science and Technology, Publisher: UNIV AEGEAN, Pages: A877-A884, ISSN: 1106-5516

Conference paper

Wong SM, Hobbs RE, Onof C, 2005, An adaptive response surface method for reliability analysis of structures with multiple loading sequences, STRUCTURAL SAFETY, Vol: 27, Pages: 287-308, ISSN: 0167-4730

Journal article

Wong S M, Hobbs R E, Onof C J, 2005, Element and System Risk Considerations in Highway Bridge Assessment, London, Current and future trends in bridge design, construction and maintenance 4, Publisher: Thomas Telford, Pages: 473-484

Conference paper

Wong S M, Onof C J, Hobbs R E, 2005, Models for the evaluation of the costs of bridge failure, Proc Institution of Civil Engineers, Bridge Engineering, Vol: 158, Pages: 117-128, ISSN: 1478-4637

Journal article

Lekkas DF, Onof C, Lee MJ, Baltas EAet al., 2004, Application of artificial neural networks for flood forecasting, Global Nest Journal, Vol: 6, Pages: 205-211, ISSN: 1790-7632

In hydrology, as in a number of diverse fields, there has been an increasing use of Artificial Neural Networks (ANN) as black-box simplified models. This is mainly justified by their ability to model complex non-linear patterns; in addition they can self-adjust and produce a consistent response when ‘trained’ using observed outputs. This paper utilises various types of ANNs in an attempt to assess the relative performance of existing models. Ali Efenti, a subcatchment of the river Pinios (Greece), is examined and the results support the hypothesis that ANNs can produce qualitative forecasts. A 7-hour ahead forecast in particular proves to be of fairly high precision, especially when an error prediction technique is introduced to the ANN models.

Journal article

Onof C, Townend J, 2004, Modelling 5-minute rainfall extremes, Hydrology: science and practice for the 21st century, Publisher: British Hydrological Society, Pages: 203-209

Conference paper

Onof C, 2004, Mathematical expressions of generalised moments used in single-site rainfall models, FD2105 project, Publisher: DEFRA, 8

Report

Koutsoyiannis D, Onof C, Wheater HS, 2003, Multivariate rainfall disaggregation at a fine timescale, WATER RESOUR RES, Vol: 39, Pages: 1173-1190, ISSN: 0043-1397

[1] A methodology for spatial-temporal disaggregation of rainfall is proposed. The methodology involves the combination of several univariate and multivariate rainfall models operating at different timescales, in a disaggregation framework that can appropriately modify outputs of finer timescale models so as to become consistent with given coarser timescale series. Potential hydrologic applications include enhancement of historical data series and generation of simulated data series. Specifically, the methodology can be applied to derive spatially consistent hourly rainfall series in rain gages where only daily data are available. In addition, in a simulation framework the methodology provides a way to take simulations of multivariate daily rainfall ( incorporating spatial and temporal nonstationarity) and generate multivariate fields at fine temporal resolution. The methodology is tested via a case study dealing with the disaggregation of daily historical data of five rain gages into hourly series. Comparisons show that the methodology results in good preservation of important properties of the hourly rainfall process such as marginal moments, temporal and spatial correlations, and proportions and lengths of dry intervals as well as a good reproduction of the actual hyetographs.

Journal article

McIntyre N, Lees M, Wheater H, Onof C, Connorton Bet al., 2003, Evaluation and visualisation of risk to water resources, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-WATER AND MARITIME ENGINEERING, Vol: 156, Pages: 1-11, ISSN: 1472-4561

Journal article

McIntyre N, Lees M, Wheater H, Onof C, Connorton Bet al., 2003, Evaulation and visualisation of risk to water resources, Proceedings of the Institution of Civil Engineers: Water and Maritime Engineering, Vol: 156, Pages: 1-11, ISSN: 1472-4561

A traditional difficulty encountered in water resource planning is the inherent uncertainty in demand and supply capability. Over recent years this uncertainty has increased for the UK water industry, owing for example to forecasts of climate change and impending directives from Europe, and in the face of such uncertainty it is no longer justifiable to design water resource systems in a deterministic fashion. Design objectives should be risk-based, and it is likely that both investors and regulators will soon request formal risk evaluation prior to major investment or strategic decisions. Consequently, there is a need for probabilistic, or risk-based, approaches to water resource assessment. A methodology for evaluation and visualisation of risk to security of water resources is presented, based on hydrological frequency of occurrence and uncertainty-based analysis of headroom (that is, the difference between supply capability and demand). The methodology makes it possible to calculate and visualise the probability of system failure for particular hydrological conditions or the probability of system failure in an arbitrary year, and to make preventive planning or operational decisions. The proposed approach is illustrated with a case study.

Journal article

Skaugen T, Astrup M, Langholt EG, Onof C, Udnaes HCet al., 2003, Using simulated time series of rainfall and temperature for design and long term flood warning, International commission for the hydrology of the Rhine basin, proceedings for the international conference on flood estimation, Berne, Switzerland, 6 - 8 March 2002, Pages: 247-253

Conference paper

Chandler R, Wheater HS, Isham VS, Onof C, Bate S, Northrop PJ, Cox DR, Koutsoyiannis Det al., 2002, Generation of spatially consistent rainfall data, Continuous river flow simulation: methods, applications and uncertainties, Publisher: British Hydrological Society; 2002, Pages: 59-66

Conference paper

Onof C, Townend J, Bogner K, 2002, Time-series rainfall tool and design event analysis for climate change, Publisher: HR Wallingford, SR607

Report

Wong SM, Hobbs RE, Onof C, 2002, Element and system risk-based evaluation of highway bridges (Available on CD-ROM), ASRANet proceedings, Glasgow, July 2002

Conference paper

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