Some results of zero-order analysis Ellen Douglas, 6/10/03 Methods (analyses at 6-min resolution except where noted): Aggregated Landscan 2000 population data: original at 1 km resolution Delineated floodplains: min slope < 0.0005 within 15 km of a river or drainage canal (criteria from previous work). Selected 30-min grids cells within pan-tropical domain that were classified as dissected terrain (Meybeck, Green and Vorosmarty, 2001. A new typology for mountains and other relief classes, Mountain Research and Development, 21 (1): 34-45.) This will highlight basins in which populations are potentially more vulnerable to major floods resulting from deforestation.

Estimate population potentially vulnerable to flooding Methods: Select total population with delineated floodplains Compute population density (pop/sq. km) (slides 6-9) Overlay population density in floodplains on map of basins with >25% area classified as highly dissected (slides 10-13). I am hypothesizing that basins with >25% of their area in high relief are more sensitive to changes in hydrology from deforestation. This means that basins in Central America and Southeast Asia are of particular concern. This hypothesis will be tested with the modeling exercise.

Estimate population potentially vulnerable to flooding In the next four slides, I’ve pointed out basins with >25% highly dissected area and with high population density at or near the mouth. These downstream populations have the potential to be greatly affected by upstream land use changes.

Magdelena Basin

Ganges Basin

Hong Basin Chao Phraya Basin Mekong Basin

Preliminary Conclusions A synoptic analysis, even at a relatively coarse resolution, allows us to compare geophysical and population attributes across the entire modeling domain. This helps us to focus our attention and test our hypotheses on basins that have the greatest potential for increased human vulnerability due to deforestation. From this analysis, it appears that southern Asia should be (and in fact is) our main focus due to high population densities within floodplains (esp near the river mouths) coupled with high relief basins.