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Using genetic algorithms to calibrate a water quality model.

Liu, Shuming and Butler, David and Brazier, Richard E. and Heathwaite, A. Louise and Khu, Soon-Thiam (2007) Using genetic algorithms to calibrate a water quality model. Science of the Total Environment, 374 (2-3). pp. 260-272. ISSN 0048-9697

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Abstract

With the increasing concern over the impact of diffuse pollution on water bodies, many diffuse pollution models have been developed in the last two decades. A common obstacle in using such models is how to determine the values of the model parameters. This is especially true when a model has a large number of parameters, which makes a full range of calibration expensive in terms of computing time. Compared with conventional optimisation approaches, soft computing techniques often have a faster convergence speed and are more efficient for global optimum searches. This paper presents an attempt to calibrate a diffuse pollution model using a genetic algorithm (GA). Designed to simulate the export of phosphorus from diffuse sources (agricultural land) and point sources (human), the Phosphorus Indicators Tool (PIT) version 1.1, on which this paper is based, consisted of 78 parameters. Previous studies have indicated the difficulty of full range model calibration due to the number of parameters involved. In this paper, a GA was employed to carry out the model calibration in which all parameters were involved. A sensitivity analysis was also performed to investigate the impact of operators in the GA on its effectiveness in optimum searching. The calibration yielded satisfactory results and required reasonable computing time. The application of the PIT model to the Windrush catchment with optimum parameter values was demonstrated. The annual P loss was predicted as 4.4 kg P/ha/yr, which showed a good fitness to the observed value.

Item Type: Article
Journal or Publication Title: Science of the Total Environment
Uncontrolled Keywords: Diffuse pollution ; Genetic algorithm ; Model calibration ; Phosphorus Indicators Tool
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 31441
Deposited By: Mr Richard Ingham
Deposited On: 18 Jan 2010 11:48
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:58
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/31441

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