Thesis (M.Eng.)--Chulalongkorn University, 2009

Geographic Information System (GIS) is a system widely used in many organizations such as government organizations, private organizations, and state enterprises. Metropolitan Waterworks Authority (MWA) is an important state enterprise providing public supply in order to support customer growth and rise. In order to support efficiently, MWA uses the Geometric Information System to develop the services focusing on positions and locations in particular. Accordingly, Google Earth is a choice for improving and keeping the map data of Metropolitan Waterworks Authority up to date. The aim of the research is to study the map data of Metropolitan Waterworks Authority and Google Earth, examine the comparative study of datum coordinate of both systems and improve the GIS of MWA in Google Earth to apply the updated data to the GIS of MWA. In this research, the researcher selected Samutprakarn Branch Office of MWA as a test area to find an improving algorithm of MWA land base; the test area covers serviced areas approximately 463.743 sq.km and there are customer connections around 149,473. The result of the study reveals that Google Earth has the similarity of data to the GIS of MWA. The algorithm of editing the overlay of both data shows minimal residuals after performing the datum transformation which can be used to improve the GIS of MWA and help planning an infrastructure and water loss management system quickly, correctly and efficiently.