Abstract

Mapping Freshwater Ecological Systems with Nested Watersheds in South America
Track: Ecology and Conservation
Author(s): Leonardo Sotomayor, Paulo Petry

Using watershed delineation tools created by Fitzhugh (2005) in an ArcINFO environment we performed a wall-to-wall decomposition of South America's river basins into a series of catchments in five different sizes classes: 100-1,000 square kilometers, 1,000-10,000 square kilometers, 10,000-100,000 square kilometers, 100,000-1,000,000 square kilometers and 1,000,000-10,000,000 square kilometers. The five size classes were then nested in size hierarchy with the Union command in ArcINFO. The result was a detailed depiction of catchment topology, their headwaters, large river basins and large river main stems. We produced over 36,800 watershed units covering the entire South American continent. We added a series of abiotic attributes to each catchment unit including climate, geology, geomorphology and hydrography. Hydrographic attributes were extracted from a DEM derived stream network, for a total of 162 attribute columns. Finally, we used a series of classification tools to find unique combinations that were classified into freshwater ecological systems.

Leonardo Sotomayor
The Nature Conservancy
Av. De Los Naranjos N44-491
y Azucenas (Monteserrin)
Quito , Pichincha N/A
Ecuador
Phone: 225 7138
E-mail: leosotomayor@yahoo.com

Paulo Petry
The Nature Conservancy
11 Ave. de Lafayette
Boston , Massachusetts 02111-1736
United States
Phone: 617 542-190
E-mail: ppetry@tnc.org