This project was set up to investigate the level of accuracy which can be expected for slope and altitude values derived from low-cost Digital Elevation Models (DEMs). Eight gridded DEMs were generated from digitized contour maps at a range of scales:1:10,000 1:25,000 1:100,000 1:200,000 - and using a range of contour intervals 25m, 50m and 100m. A Control DEM was then produced using large scale aerial photographs (1:28,000) which were registered for auto-extraction of z-values using Helava software and accuracy tested using 91 differentially measured GPS ground control points.

Will intensifying the road network around market areas produce greater economic returns and less environmental damage than extending the road network into new areas?Rural roads promote economic development but also facilitate deforestation. To explore the trade-offs between development and environmental damage posed by road building, Chomitz and Gray develop and estimate a spatially explicit model of land use.