Study on Spatial-Temporal Urban Growth and Land Consumption Patterns of Thimphu, Bhutan Using Multi-Temporal Satellite Images

Abstract

Like many other countries, Bhutan is also experiencing rapid trend of urban expansion mainly due to out-migration from rural to urban areas particularly in capital city, Thimphu. This study focuses on the dynamics of urban expansion, evaluating urban growth and land consumption pattern of Thimphu, using multi-temporal Landsat images during the year 1990-2018. The main aim of the study is to perform supervised classification to classify built-up area, green area, bare-land and others (water bodies, agricultural lands, etc…) and to perform a change analysis from the viewpoint of increasing the built-up areas (man-made structures) and decreasing in green and open spaces. Moreover, the study also highlights how has the land consumption pattern of the region changed over the years. The findings of the study confirmed that the Thimphu city has its built-up areas increased during 1990-2018 with net growth of 4.63 km2 (106.19%). The urban area was 4.36 km2 in 1990, 5.80 km2 in 2000 (33.03% growth), which increased to 7.24 km2 in 2013 (24.83% growth) and 8.99 km2 (24.17% growth) in 2018. The study also showed that there is decrease in land consumption between 1990-2018. In 1990, land consumption was 155.65 m2 per person which decreased to 78.48 m2 per person in 2018. This decrease in land consumption indicate that the city is experiencing increased densification between the years 1990-2018. The classifier performance evaluation was done using overall accuracy and kappa coefficient. The classification produced an overall accuracies ranging between 78.74% to 90.46 % and overall kappa statistics between 0.72 to 0.87 for all years indicating classification accuracy of moderate to substantial accuracy.