The Kangchenjunga Conservation Area (KCA, Nepal) was the subject of a comparative study on land use/land cover change, using the maps and air photographs available for two different years (1978/79 and 1992). Digitised land use maps for 1978 (LUM78) and topographical maps for 1992 (TOPO92) were first interpreted using a Geographic Information System (GIS); this was followed by comparative interpretation of black and white air photographs from the same years. Lelep, Sekhathum–Amjilesa, Syajunma and Ramsyampati were the four areas selected for analysis.
The initial map interpretation of LUM78 and TOPO92 implied that considerable changes in land use/cover had occurred between 1978/79 and 1992. Forestland was shown to have decreased by 62.5% (23.15 km2), agricultural land to have increased by 35.7% (1.49 km2), and shrubland to have increased by 238.2% (30.16 km2). Grazing land, with an area of 22.57 km2 on the 1978/79 and 1992 imagery, appeared to have disappeared completely by 1992. An interpretation of air photographs for the same period, however, revealed that the actual changes were far smaller than those inferred from the map interpretation: decrease in forest and grazing lands by 14.9% (5.45 km2) and 77.9% (2.75 km2), respectively, and increase in agricultural and shrublands by 4.9% (0.21 km2) and 19.7% (4.41 km2), respectively. The results of a questionnaire survey of the local inhabitants confirmed that no significant changes had occurred. The discrepancies identified highlight the problems inherent in assigning land categories. In particular, distinctions made on the LUM78 material between shrub, grazing land, and barren land were inappropriate. Similarly, forest and shrublands were incorrectly assigned in TOPO92. Caution must be exercised when using such information; verification from other sources is needed.
