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Monitoring of changes in land use/ land cover using multi- sensor satellite data
VECTOR module of ERDAS IMAGINE software has been used for on-screen digitization and to obtain the boundary of study area from the modified master plan 2001 of Allahabad. By using this as raster mask, LISS-III and LISS-II imageries of the study area have been extracted.
 Figure 1: Methodology Adopted 2 Preparation of Multi-date Land Use/ Land Cover Maps For monitoring the changes in the pattern of land utilization, preparation of multi-date land use/ land cover maps are necessary. These maps are also required for ensuring planned development of any region. After the registration of digital images of the Allahabad city, the training samples for each land use and land cover class are collected for both LISS-II and LISS-III imageries. Limited field visits have been undertaken for collecting the training samples. The various land use/ land cover classes selected include built-up, agriculture, sand, water, scrub and open/ barren land. The multispectral classification was carried out using supervised classification techniques with maximum likelihood classifier. The overall accuracy of the classification is finally obtained through the computation of confusion matrix to assess the reliability of the prepared maps. Analysis of Results .The land use/ land cover maps prepared using the methodology described above have been shown in Figure 2 (LISS-II data of 1994) and Figure 3 (LISS-III data of 2000). The various land use and land cover classes delineated include built-up, agriculture, sand, water, scrub and open/ barren land. The spatial coverage of each class may be visualized on both maps. The area of each class for LISS-II (year 1994) and LISS-III (year 2000) data has been compiled in Table 1. An unbiased set of testing samples has been selected from the reference data for assessing the classification accuracy, which comes out to be 79.5% for LISS-II and 78.2 for LISS-III data respectively. Table 1 also shows the change pattern in the land utilization from year 1994 to 2000 for the Allahabad city. From LISS-III land use/ land cover map of year 2000, it may be seen that built up area constitutes 7.5% of total area, while the agriculture and scrub covers 47.0% and 13.9% area respectively. In year 1994, the built up area obtained from digital image processing techniques has been 6.3% of the total area. The agriculture and scrub covers 50.0% and 14.3% area respectively. The open/ barren land constitutes 22.3% in year 2000 while it was 19.7% in 1994.  Figure 2: Land Use/Land Cover Map |