Monitoring deforestation in Kenya

Multi‐temporal data is used to determine the rate of deforestation between the years 1976, 1987 and 2000. Three Landsat images, for each period, are pre‐processed, mosaicked and normalized difference vegetation index (NDVI) values computed. Based on the values, totally non‐forested areas are masked out. The forested areas, both partially and wholly, show a very high degree of correlation between all the bands (reflective), thus necessitating an application of principal components transformation. The first two principal components and NDVI values are used in K‐means unsupervised classification to distinguish forest from non‐forest areas (that appeared as forest at first). Comparison of the resulting thematic maps gives an annual deforestation rate of roughly 15,000 ha. or 2% between any two epochs.