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Land use types have become more and more complicated along with growth in economic development and social changes. Various domestic competent target business authorities, such as Construction and Planning Agency of Ministry of the Interior (CPAMI); Soil and Water Conservation Bureau, Council of Agriculture, Executive Yuan (SWCB); and Water Resources Agency of MOEA (WRA), have individually conducted land use monitoring within their jurisdiction. However, in response to different business needs in the past, CPAMI, SWCB, and WRA each executed land use monitoring by employing different monitoring frequencies, reporting approaches, and satellite images with different resolutions according individual needs. Thus, it hindered governmental resource sharing.

To facilitate the integration of government resources, the Ministry of Interior (MOI) convened meetings beginning from 2012, and had reached the conclusion that the National Land Surveying and Mapping Center (NLSC), MOI should integrate the existing monitoring plans of CPAMI, SWCB, and WRA from 2014 until 2017. Acting on the instruction of integrating existing governmental monitoring plans by MOI, the NLSC began the integration plan in 2014. Based on the original monitoring resources, the monitoring frequency of each agency was adjusted to once every 2 months, and the satellite images with the ground resolution from 1.5 m to 2.5 m were chosen to be used. NLSC effectively integrated monitoring resources of various agencies in order to reduce repeated investment of government resources and enhanced the effectiveness.

In accordance with the Spatial Planning Act (Promulgated on January 6, 2016), the central competent authority shall survey land cover and monitor land use on a regular basis. Since 2018, the national land use monitoring has been planned and handled by CPAMI.

The implementation of land use monitoring and integration work of NLSC from 2014 to 2017 are as follows.

  • Monitoring refers to the detection of variation of land use nationwide by interpretation from satellite eimageries with technology of the geographic information system (GIS). The suspect information of variation points will be sent to all relevant agencies via the Internet for them to dispatch personnel for onsite audit, result feedback, and follow-up checking of subsequent processing in order to be fully aware of the changes of lands. In addition to improving the traditional reporting and crack-down methods for land use violations, the use of high-tech digital method for long-term land use monitoring can also result in effective deterrence of unlawful conducts, and utilization and management of land resources.
  • High resolution satellite images
    • The imagery of the Formosa-2 was primarily chosen for this plan, while that of the SPOT was secondly. Before use, images were processed with geometric correction. Image variations of ground truths of the same place captured at different times were analyzed automatically later by computer-based comparison software. The suspected variation spots will be screened out manually by analyzing variations of textures, shapes, and spectral characteristics and will be checked with color aerial photographs, base maps, land use maps, electronic maps, and slope shades.
      Image variation analysis result

      Image variation analysis result
      (Left) former satellite images    (Right) later satellite images

    • The suspected variation spots will be sent to the individual land supervisory agencies in local governments via internet reporting system for conducting onsite audits. The ground truths of the onsite checking will be sent back for tracking the subsequent processes in order to totally realize and crackdown any change situations.
      A case of reported suspected violations

      A case of reported suspected violations

      (Upper left) Former satellite image
      (Lower left) Later satellite image overlapped with variation points of violation
      (Right) Illegal construction determined by onsite inspection

  • National land use monitoring integration operation
    • The NLSC was commissioned to integrate the then existing satellite imagery monitoring plans responded by the Construction and Planning Agency of Ministry of the Interior, Water Resources Agency of Ministry of Economic Affairs, and Soil and Water Conservation Bureau of Council of Agriculture of Executive Yuan since 2014.It is to reduce the repeated investment of government resources and hopefully still can quickly grasp current status of land use and the information of changes.
    • In addition to the detection of regular changes of land use, the national land use monitoring can also be conducted for the relevant business requirements and in response to emergency disaster, where the capturing and processing of images of specific area can be conducted based on high resolution satellite images for analyses of detected changes. Operations contain the data update and analysis within the scope of approved non-urban land development permit, development and utilization analysis of existing lands in industrial zones and parks, detection of coastal line variations, detection of marine area variations, result of deep trench establishment, and interpretation result of exposed land of river bed. This integration system has provided the services to meet the requirements of national land management of all administrative agencies and serve as the reference for decision making
      • An analysis of development and utilization of existing lands in industrial zones and parks shows that the buildings distribution within the industrial zones and parks can be interpreted by the comparison using latest satellite images for better understanding of the current status of actual development or the idle status of undeveloped lands.
        Industrial park map based on overlapped images of Formosa-2 satellite  Result of interpretation of buildings in the industrial park

        Development Rate Analysis of Linkou 1st Industrial Park

        (Left) Industrial park map based on overlapped images of Formosa-2 satellite
        (Right) Result of interpretation of buildings in the industrial park

      • Coastal line variation detection
        The detection and digitization of coastal line variation should be implemented while keeping the statistics of variations of natural and artificial coastal lines.
        Comparison among multi-temporal satellite images and onsite photographs of artificial and natural coastal lines

        Comparison among multi-temporal satellite images
        and onsite photographs of artificial and natural coastal lines

      • Result of deep trench establishment and interpretation of exposed land of river bed should be provided to all River Bureaus of Water Resources Agency as the reference and application for farm planning and dike renovation.
        Deep trench results of Gaoping River over the years

        Deep trench results of Gaoping River over the years