The Base Maps

Creating maps of Kona for the public workshops presented some unique challenges. Two sets of base maps were created: urbanized areas (right) and rural areas (not shown). This was necessary to deal with the vast difference in scale between the urban area, and the 800 square mile area that comprises of both North and South Kona. A base map showing developed, protected, and vacant land was created for the workshop exercise as well as supporting maps for several thematic categories: Existing Land Use, Natural Resources, General Planned Land Use, Infrastructure, and Ownership (not shown). This required significant data gathering, coordination, verification, and clean up.

One particularly vexing problem with data collection was the lack of accurate current and historical land use maps, which made mapping developed areas and understanding land consumption trends difficult. Satellite imagery of land cover could not be used because it was incomplete and uneven, or simply not available for some years due to the persistent cloud cover that is typical of the higher-elevation rain forests.

To address this challenge, CommuityViz GIS decision support tools were used to create a land use model to determine whether parcels should be considered "developed" or "undeveloped". The determination was made by analyzing tax assessors' data over a ten year period, using metrics of parcel size, assessed land use, and assessed valuation of improvements. To calibrate and validate the land use model, the model run for the one year where there was complete satellite imagery of land cover, and the two layers were compared for false-positives, and false-negatives. Then the calibrated model was run for all ten years, producing a consistent "close enough is good enough" estimate of land use consumption that could be projected out for 15 years to 2020.

Click on map above for full-size image.

The map on the left (below) shows the original land use classifications based on tax assessors' records. Large areas were incorrectly classified as "mixed use" (gray) or "agricultural" (light green). The map on the right shows the corrected land use.