Land Surveys & Mapping to Underpin Cadastral Mapping in LAMP Project Sites

LAMP evLAMP_ARC1_1aluated and subsequently adopted for use a standard surveying system, map projection system, map layout and base mapping standards suitable for both the project and the longer term use by SLRD. The standards were applied in cadastral operations in two townships in 2015. These decisions are vital to underpin the long term strengthening of the cadastral system for both SLRD purposes and needs of the wider spatial users.

Existing cadastral maps are not located on a geodetic network and do not show any map grid. The extent of each Kwin map in farmlands is described administratively and Kwin maps do not form continuous map coverage of the land. Existing base maps are in the form of line maps from many years ago. These limitations were addressed with new cost effective solutions.

The existing national first and second order networks are managed by the Survey Department. The network was evaluated and adopted for use by LAMP. A suitable map projection system was adopted for all LAMP mapping and LAMP maps show this map grid. To complement the Kwin maps a format for cadastral index maps was designed as well as a map numbering system which are unique across the whole country. Up to date satellite image maps with suitable specifications and ortho-rectified to the LAMP survey and mapping system were designed to be used as base maps.

Third order survey control was placed in the survey area of LAMP from GNSS survLAMP_ARC4ey from the second order network. These were used for (i) control of the ortho-rectification of the satellite imagery; (ii) control for establishing temporary base stations to support GNSS RTK cadastral surveys on the basis of one base station per Kwin map in farmlands; (iii) control for geo-referencing cadastral block maps in urban areas.

Using GNSS surveys with redundant observations from a pair of second order stations, the required accuracy of third order control was accomplished. Station summaries were produced to document the location and kind of the marks. The satellite imagery was taken just one month before its initial use (January / February 2015) in the dry season when the bunds are highly visible. The spatial resolution of the imagery was very good (50 cm).

Unlike in small and medium sLAMP_ARC3cale mapping, in large scale mapping, such as cadastral surveys in farmland and urban locations, there is a need for a survey control network in order to avoid error accumulation. The LAMP Project has addressed this problem and demonstrated its effectiveness and methodology in supporting GIS and field survey applications.

LAMP is working on its target of 20 Kwin maps to be updated during 2015. It is using the adopted survey and mapping system which is suitable for nation-wide roll-out.