CREATING A STANDARDIZED SPATIAL DATABASE FOR THE ISLAND OF TRINIDAD, WEST INDIES

Commencement of an aggressive groundwater exploration and development program in Trinidad, West Indies, required a thorough hydrogeologic assessment of the island. A digital spatial database was created as a foundation for data integration and analysis. The resulting database links output of a proprietary recharge model with hydrolithologic and structural interpretations using GIS as the unifying element.

Completing the investigation and building the spatial database required the creation of new data, including the delineation of watersheds. Prior to this study, available basin maps for Trinidad consisted of 23 hand-delineated watersheds corresponding to existing gaging stations. These maps were published and available in paper format only. Over 200 watersheds were delineated based upon digital elevation data and the previously defined basins. Sample watersheds based upon digital elevation showed good agreement with the 1:25,000 hand-delineated basins. These watersheds, along with other data such as lineaments, DEMs, soils, landcover, satellite and radar imagery, geology, well logs, and digital raster graphs comprise the GIS database. This database may now be considered the most comprehensive spatial database available in digital format for Trinidad.

Data repositories (mostly paper maps and records) were found to be relatively abundant in Trinidad, while acquiring the data was costly and difficult partly due to the active and competitive nature of onshore and offshore petroleum exploration. Existing geologic and cultural maps are based on a variety of projections and units, from Cassini to Universal Transverse Mercator (UTM), and links to meters. Quality control issues were a pervasive and sometimes prohibitive factor in the database development.