Top-down approach for generating spatial database at cadastral level- A Sikkim Himalayan experience


Location and Extent of Study Area

Name of Study Area Rate Chhu Watershed
Spatial Information Source 78/11, 78/15, Classified RS Image and Land Survey Map.
   
Geographical Location 27° 20’30’’ and 27° 30’30" North
  88° 33’57" and 88° 45’50" East
   
Total Area Covered 87.34 sq. km. (Spans calculated)
   
Spatial Information Watershed map, contour map, forest density map (1988), land use map (1963), roads, settlement, river and drains and soil maps, streams maps and cadastral map


Present situation of land record in Sikkim is that out of 4 districts, attribute information related to land is almost complete in three districts. Online mutation is under progress in one district. Besides this, Land Revenue Department has two sets of survey records pertaining to the old survey 1952 and the second pertaining to the more recent survey of 1976-82. However, for various reasons, 1952 cadastral survey maps are reference point for solving land related litigations in Sikkim. There are near 4000 cadastral maps. Each village has around 3-4 maps. The maps of rural areas are 1 mile = 16’’ scale and that of urban areas are 1 mile = 64’’ scale.

In this case study an attempt has been made to develop necessary spatial database at the cadastral level and investigate into the resource distribution and utilization at plot level. In this study, cadastral map of Tintek block was traced and digitized and GIS based study performed.



In this study, a top-down approach has been adopted. Here top-down approach means, that first GIS based analysis is performed at watershed level for micro-level planning model, then at one lower level a cadastral level study is done.

The usual method adopted in development of Land Information System (LIS) is bottom-up approach that is several cadastral maps are digitized, geocoded and then mosaic together to generate village or block boundary. However this approach is more tedious and prone to errors as there is a very limited possibility of cartographic adjustment. But, in top-down approach, one has the village or block map as a reference, which can help in minimizing the geographic errors, and proper overlays can be obtained and hence maps can be cartographically adjusted. Besides this database development and implementation of pure LIS system can become much easier and realistic.



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