Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Runoff sources and land cover change in the Amazon: an end-member mixing analysis from small watersheds

Full text
Author(s):
Show less -
Neill, Christopher [1] ; Chaves, Joaquin E. [1] ; Biggs, Trent [2] ; Deegan, Linda A. [1] ; Elsenbeer, Helmut [3] ; Figueiredo, Ricardo O. [4] ; Germer, Sonja [3] ; Johnson, Mark S. [5] ; Lehmann, Johannes [6] ; Markewitz, Daniel [7] ; Piccolo, Marisa C. [8]
Total Authors: 11
Affiliation:
[1] Marine Biol Lab, Ctr Ecosyst, Woods Hole, MA 02543 - USA
[2] San Diego State Univ, Dept Geog, San Diego, CA 92182 - USA
[3] Univ Potsdam, Inst Geoecol, D-14476 Golm - Germany
[4] EMBRAPA Meio Ambiente, Jaguariuna, SP - Brazil
[5] Univ British Columbia, Dept Earth & Ocean Sci, Inst Resources Environm & Sustainabil, Vancouver, BC V6T 1Z4 - Canada
[6] Cornell Univ, Dept Crop & Soil Sci, Ithaca, NY 14853 - USA
[7] Univ Georgia, DB Warnell Sch Forest Resources, Athens, GA 30602 - USA
[8] Univ Sao Paulo, Lab Ciclagem Nutrients, Ctr Energia Nucl Agr, BR-13416000 Piracicaba, SP - Brazil
Total Affiliations: 8
Document type: Journal article
Source: BIOGEOCHEMISTRY; v. 105, n. 1-3, p. 7-18, SEP 2011.
Web of Science Citations: 22
Abstract

The flowpaths by which water moves from watersheds to streams has important consequences for the runoff dynamics and biogeochemistry of surface waters in the Amazon Basin. The clearing of Amazon forest to cattle pasture has the potential to change runoff sources to streams by shifting runoff to more surficial flow pathways. We applied end-member mixing analysis (EMMA) to 10 small watersheds throughout the Amazon in which solute composition of streamwater and groundwater, overland flow, soil solution, throughfall and rainwater were measured, largely as part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia. We found a range in the extent to which streamwater samples fell within the mixing space determined by potential flowpath end-members, suggesting that some water sources to streams were not sampled. The contribution of overland flow as a source of stream flow was greater in pasture watersheds than in forest watersheds of comparable size. Increases in overland flow contribution to pasture streams ranged in some cases from 0% in forest to 27-28% in pasture and were broadly consistent with results from hydrometric sampling of Amazon forest and pasture watersheds that indicate 17- to 18-fold increase in the overland flow contribution to stream flow in pastures. In forest, overland flow was an important contribution to stream flow (45-57%) in ephemeral streams where flows were dominated by stormflow. Overland flow contribution to stream flow decreased in importance with increasing watershed area, from 21 to 57% in forest and 60-89% in pasture watersheds of less than 10 ha to 0% in forest and 27-28% in pastures in watersheds greater than 100 ha. Soil solution contributions to stream flow were similar across watershed area and groundwater inputs generally increased in proportion to decreases in overland flow. Application of EMMA across multiple watersheds indicated patterns across gradients of stream size and land cover that were consistent with patterns determined by detailed hydrometric sampling. (AU)

FAPESP's process: 03/13172-2 - The role of Amazonian fluvial systems in regional and global carbon cycles: CO2 evasion and land-water interactions
Grantee:Reynaldo Luiz Victória
Support Opportunities: Research Projects - Thematic Grants