, 105:7 | Cite as

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

  • Christopher Neill
  • Joaquin E. Chaves
  • Trent Biggs
  • Linda A. Deegan
  • Helmut Elsenbeer
  • Ricardo O. Figueiredo
  • Sonja Germer
  • Mark S. Johnson
  • Johannes Lehmann
  • Daniel Markewitz
  • Marisa C. Piccolo


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.


Cattle pasture Deforestation Flowpaths Principal components analysis Overland flow Soil solution 



This work was supported by National Science Foundation (DEB-0315656, DEB-0640661), the NASA LBA Program (NCC5-686, NCC5-69, NCC5-705, NNG066E88A) and by grants from Brazilian agencies FAPESP (03/13172-2) and CNPq (20199/2005-5). We thank Paul Lefebvre for producing the Amazon Basin map.

Supplementary material

10533_2011_9597_MOESM1_ESM.pdf (1.2 mb)
Supplementary material 1 (PDF 1205 kb)


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Christopher Neill
    • 1
  • Joaquin E. Chaves
    • 1
    • 9
  • Trent Biggs
    • 2
  • Linda A. Deegan
    • 1
  • Helmut Elsenbeer
    • 3
  • Ricardo O. Figueiredo
    • 4
  • Sonja Germer
    • 3
    • 10
  • Mark S. Johnson
    • 5
  • Johannes Lehmann
    • 6
  • Daniel Markewitz
    • 7
  • Marisa C. Piccolo
    • 8
  1. 1.The Ecosystems Center, Marine Biological LaboratoryWoods HoleUSA
  2. 2.Department of GeographySan Diego State UniversitySan DiegoUSA
  3. 3.Institute of GeoecologyUniversity of PotsdamGolmGermany
  4. 4.Embrapa Meio AmbienteJaguariúnaBrazil
  5. 5.Department of Earth and Ocean Sciences, Institute for Resources, Environment and SustainabilityUniversity of British ColumbiaVancouverCanada
  6. 6.Department of Crop and Soil SciencesCornell UniversityIthacaUSA
  7. 7.D. B. Warnell School of Forest ResourcesUniversity of GeorgiaAthensUSA
  8. 8.Laboratório Ciclagem de Nutrients, Centro de Energia Nuclear na AgriculturaUniversidade de São PauloPiracicabaBrazil
  9. 9.Science Systems and Applications Inc., NASA Calibration and Validation OfficeHalethorpeUSA
  10. 10.Berlin-Brandenburg Academy of Sciences and HumanitiesBerlinGermany

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