Census Mapping Project, Nepal

HMG Survey Department of Nepal
Ministry for Foreign Affairs, Finland / DANIDA, Denmark / European Commission
1998 – 2003

The last Population and Housing Census in Nepal was carried out in mid of 2001 by Central Bureau of Statistics. During pre-enumeration phase among others the necessary geographic information was collected and prepared to be used in actual enumeration phase as well as for population GIS during the post-enumeration.

At the end of 1998 FINNMAP was selected as contractor to produce the required geographic information jointly with HMG Survey Department of Nepal. The standards and specifications developed during the topographic mapping program are utilized in this project.

The existing topographic maps (1992 – 2002) were digitized during the Census Mapping Project in order to create a digital database, which were used to produce enumeration maps for Census. These maps were plotted for each enumerator on his/her enumeration area in order to ensure a comprehensive enumeration. In the post-enumeration phase this database was used for several GIS’s of population and housing. Digitizing is based on automatic scanning of drawing originals and semi-automatic vectorizing and classifying of scanned data according to the national specifications. In addition to the use of Census, this database will base a core for the National Topographic Database, which is administrated by the Survey Department.

Orthophotos in scale 1:5 000 or 1:10 000 were produced by digital methods on densely populated areas to help planning and execution of enumeration work. Production of orthophotos in scale 1:5 000 was based on new aerial photography in scale 1:15 000, which was completed in December 1998 – January 1999. Totally 37 municipalities and urban areas were photographed utilizing GPS-supported flight management and airborne GPS-observations. Necessary ground control has been also measured for each area for aerial triangulation. Orthophotos in scale 1:10 000 were prepared on semi-urban areas using existing aerial photographs.

The orthophotos were produced by digital methods. All necessary aerial images are digitized using a high-resolution photogrammetric scanner. Digital images are then used for automatic processing: aerial triangulation, generation of digital terrain model as well as rectification of images and orthophoto map production. Final products for the census are orthophoto maps for the enumeration areas. The digital images and orthophotos are available for several users of geographic information.