PROBLEM: ERRONEOUS, OUTDATED AND UNAVAILABLE MAPS

The current maps representing the islands of the Federated States of Micronesia are hard-to-get. The main four islands, Yap, Chuuk, Pohnpei and Kosrae have been mapped by the United States Geological Survey in the 1960s with reasonable detail and accuracy, and the resultant 1:25,000 topographic maps are still used as the main geographic reference. Maps for the remaining 38 islands/atolls are practically unobtainable. (Some topographic maps were made following World War II by the US Army Corps of Engineers, but these maps are outdated and extremely rare).

The current maps of Micronesian atolls are not accurate. Due to their relative remoteness, small size and, most of all, frequent geomorphic changes (gradual or storm-induced changes in coral/sediment accumulation and erosion), Micronesian atolls and small islands at present lack any maps, paper or digital, that would realistically portray the exact situation. What maps may be available for Micronesian atolls are neither geospatially nor geomorphically accurate. Errors such as absence of recently stabilized islets, presence of land destroyed by typhoons decades ago, and wrong island shapes and sizes are so common as to render extant maps useless. Tragically, at least some of the numerous shipwrecks in the FSM have been caused by faulty maps.

SOLUTION: ACCURATE, ORIGINAL LARGE-SCALE GIS DATASETS

IREI's aim is to produce accurate, up-to-date large-scale digital map datasets for all Outer Islands in the FSM (all islands except for the main four, which are well mapped at present.) Over the past several years, we have collected all known modern paper maps of the FSM Outer Islands. They were scanned and georeferenced so that they can be viewed using Geographic Information System (GIS) software. The maps were then digitized so that all line, point and area information from the paper maps is converted into vector data (GIS coverages). This data was superimposed on best-available satellite imagery and hundreds of errors were identified (most of them reflect changes caused by typhoon episodes). GIS coverages were then revised to be consistent with remote sensing data.

Final data is field checked. With shapefiles produced based on extant maps and satellite imagery loaded into our mobile mapping units - donated to IREI by our sponsor, Thales Navigation - we visit each atoll/island in the FSM Outer Islands and verify information in the field. This has proven to be much more important than we presumed, as many islets are so small that they are hardly detectable using imagery. In many instances we generated entirely new shape files (e.g., islet coastlines) based on ground information and thus produced the most accurate GIS coverages for Micronesian atolls available anywhere. This project is still in progress, as we have dozens of islands left to visit. We hope to complete this work by the end of the year 2006, when the entire dataset will be made public.