A comparison of different methods of impervious area estimation

Chowdhury, R. and Hartcher, M. and Gardner, T. and Gardiner, R. (2010) A comparison of different methods of impervious area estimation. In: Science Forum and Stakeholder Engagement: Building Linkages, Collaboration and Science Quality, 28-29 Sept 2010, Brisbane, Australia.


Estimation of impervious area is a pre-requisite for hydro-ecological research. Previous studies identified a linear relationship between catchment impervious fraction and stream ecosystem health indicators. Therefore, an accurate estimation of catchment imperviousness is of current interest to urban hydrology researchers. In this study, three methods were compared to estimate the imperviousness of eight catchments located in South East Queensland (SEQ), as part of the Stormwater Harvesting and Reuse Project. The techniques are: (a) manual digitisation of geo-referenced aerial photos; (b) automated image analysis using Erdas IMAGINE and ESRI ArcGIS software; and (c) rainfall runoff depth relationship. For five of the catchments, standard deviations of total impervious area (TIA) percentages are less than 3.6%. For the other three catchments, standard deviation fell between 5% to 8%. The automated image analysis method underestimated results for two catchments. Major constraints of the image processing technique were shading effects and different colours of surfaces, which can be reduced by appropriate selection of signature colours and multiple iterations of a supervised classification. The rainfall–runoff method, which is considered an accurate method from an hydrology perspective, depends on availability of event-based rainfall and runoff data, however a linear relationship was not observed for all catchments. The manual digitisation technique estimated TIA reasonably well, but requires careful selection of sample area for digitisation. Whilst the method requires less GIS skill than image analysis technique, it was time consuming.

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Item Type: Conference or Workshop Item (Commonwealth Reporting Category E) (Paper)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2010 CSIRO To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO.
Faculty/School / Institute/Centre: Historic - Faculty of Engineering and Surveying - Department of Surveying and Land Information (Up to 30 Jun 2013)
Faculty/School / Institute/Centre: Historic - Faculty of Engineering and Surveying - Department of Surveying and Land Information (Up to 30 Jun 2013)
Date Deposited: 26 Jun 2018 05:38
Last Modified: 26 Jun 2018 05:38
Uncontrolled Keywords: catchment, hydrology, ecosystem, Geographical Information System, aerial photo
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090509 Water Resources Engineering
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400513 Water resources engineering
Socio-Economic Objectives (2008): D Environment > 96 Environment > 9609 Land and Water Management > 960912 Urban and Industrial Water Management
URI: http://eprints.usq.edu.au/id/eprint/34353

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