Use of Principal Component Analysis (PCA) of Remote Sensing Images in Wetland Change Detection on the Kafue Flats, Zambia

Abstract The paper describes the use of Principal Component Analysis (PCA) of remote sensing images as a method of change detection for the Kafue Flats, an inland wetland system in southern Zambia. The wetland is under human and natural pressures but is also an important wildlife habitat. A combination of Landsat MSS and TM images were used. The images used were from 24 September 1984 (MSS), 3 September 1988 (MSS), 12 September 1991 (TM) and 20 September 1994 (TM). They were geometrically co‐registered and, in the process, the 80m resolution MSS images were resampled to 30m using nearest neighbour resampling. Preliminary PCA revealed that for the MSS images most of the data variance was in near infrared reflectance while for the TM images it was in mid and thermal infrared bands. Holding sensor type constant, separate inter‐band correlation analysis for each image could indicate whether the wetland was drier or wetter on one date versus another. The 1994 image was made the reference image and equivalent green, red and near infrared bands from the other images were radiometrically normalised with those on the reference image. All the bands, three from each date, were then merged into a twelve‐band image on which PCA for change detection was undertaken. A colour composite of eigen images from the resulting principal components was used in change detection. Hydrological data, indicating long‐term reduced inflow of water into the wetland due to human regulation, help explain some of the wetland change detected. Compared to a classification comparison approach to change detection for this area, PCA was found to be very useful in indicating where change had occurred, though interpretation of the changes was difficult without reference to the input images. The methodology appears to have potential use in habitat monitoring for this wetland area.

[1]  C. Munyati,et al.  Wetland change detection on the Kafue Flats, Zambia, by classification of a multitemporal remote sensing image dataset , 2000 .

[2]  L. Gonima,et al.  Simple algorithm for the atmospheric correction of reflectance images , 1993 .

[3]  D. Kreulen,et al.  Ecology and Productivity of an African Wetland System. The Kafue Flats, Zambia , 1990 .

[4]  C. Hershner,et al.  Wetland functions and values , 1993 .

[5]  G. Howard,et al.  Proceedings of the National Seminar on Environment and Change, the Consequences of Hydroelectric Power Development on the Utilization of the Kafue Flats, Lusaka, April 1978 , 1982 .

[6]  D. Rogers.  Section 5.4, Changes in disease vector distributions, in climate change and Southern Africa; an exploration of some potential impacts and implications in the SADC region. , 1996 .

[7]  L. Eklundh,et al.  A Comparative analysis of standardised and unstandardised Principal Component Analysis in remote sensing , 1993 .

[8]  J. R. Jensen,et al.  Measurement of seasonal and yearly cattail and waterlily changes using multidate SPOT panchromatic data , 1993 .

[9]  P. Chavez.  An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data , 1988 .

[10]  R. J. Scully,et al.  Changes in experimental gillnet catches from the Kafue Floodplain, Zambia, since construction of the Kafue Gorge Dam , 1980 .

[11]  C. Munyati.  Wetland change assessment on the Kafue Flats, Zambia : a remote sensing approach , 1997 .

[12]  W. A. Rees.  The Ecology of the Kafue Lechwe: Its Nutritional Status and Herbage Intake , 1978 .

[13]  T. M. Lillesand,et al.  Remote Sensing and Image Interpretation , 1980 .

[14]  R. Schuster.  Will the Kafue Lechwe Survive the Kafue Dams? , 1980, Oryx.

[15]  Barbara B. Jackson,et al.  Multivariate data analysis : an introduction , 1983 .

[16]  Robert E. Crippen.  The regression intersection method of adjusting image data for band ratioing , 1987 .

[17]  D. Stow,et al.  Land use change detection based on multi-date imagery from different satellite sensor systems , 1990 .

[18]  R. Douthwaite.  An endangered population of Wattled Cranes (Grus carunculatus) , 1974 .

[19]  John R. Jensen,et al.  Introductory Digital Image Processing: A Remote Sensing Perspective , 1986 .

[20]  Mike Hulme,et al.  Climate change and southern Africa : an exploration of some potential impacts and implications for the SADC region. A report commissioned by WWF International and co-ordinated by the Climatic Research Unit, UEA, Norwich, UK , 1996 .

[21]  William J. Volchok,et al.  Radiometric scene normalization using pseudoinvariant features , 1988 .

[22]  A. Milne,et al.  Change Direction Analysis Using Landsat Imagery: A Review Of Methodology , 1988, International Geoscience and Remote Sensing Symposium, 'Remote Sensing: Moving Toward the 21st Century'..

[23]  M. Shao,et al.  [Models and determining methods of unsaturated soil hydraulic parameters]. , 1978, Ying yong sheng tai xue bao = The journal of applied ecology.

[24]  K. Rutchey,et al.  Inland Wetland Change Detection in the Everglades Water Conservation Area 2A Using a Time Series of Normalized Remotely Sensed Data , 1995 .

[25]  J. Verdin,et al.  Automated update of an irrigated lands GIS using SPOT HRV imagery , 1990 .

[26]  Steven A. Sader,et al.  Migratory bird habitat monitoring through remote sensing , 1991 .

[27]  Wetlands: a threatened landscape. , 1992 .

[28]  D. Muchoney,et al.  Change detection for monitoring forest defoliation , 1994 .

[29]  S. Goetz,et al.  Radiometric rectification - Toward a common radiometric response among multidate, multisensor images , 1991 .

[30]  E. LeDrew,et al.  Application of principal components analysis to change detection , 1987 .

[31]  Stuart E. Marsh,et al.  The use of archival Landsat MSS and ancillary data in a GIS environment to map historical change in an urban riparian habitat , 1995 .

[32]  W. Sheppe,et al.  Effects of Human Activities on Zambia's Kafue Flats Ecosystems , 1985, Environmental Conservation.