Transport of water, solutes and nutrients from a pasture hillslope, southwestern Brazilian Amazon

• DOI: 10.1002/hyp.6214
• Publication Date: 2006-07-24T10:18:16Z
• Authors: Trent Wade Biggs; Thomas Dunne; Takashi Muraoka
• Keywords: Subsurface Flow; Infiltration (HVAC); Water balance; Wet season; Base flow

Abstract A conceptual model of water and solute transport pathways was developed applied to a pasture hillslope in the southwestern Brazilian Amazon basin using select field measurements. Infiltration‐excess or Horton overland flow (HOF), saturation (SOF), groundwater both near‐stream zone upslope were sampled on draining 3·9 hectare for total ten storms during first half rainy season (October–November) 2002. Soil Conservation Service SCS curve number HOF an annual balance zones used calculate contribution each flowpath export. occurred rainstorms greater than 5 mm accounted ∼8% rainfall. Flow generated Sub‐surface from dominated runoff (∼19–30% rainfall). Solutes fell into three categories according flowpath. positions export phosphorus (TP) dissolved (TDP, 51–72% export). The controlled K (58–65%), nitrogen (TDN, 76–80%), (TN, ∼75%) owing relatively high concentrations large volume that flowed through zone. Na Si via (50–67% flux calculations based small are preliminary estimates designed identify broad patterns different hydrologic pathways. Additional processes, especially N removal at groundwater‐stream interface stream channel, may affect actual rates watershed scale. Whereas production is negligible forests, it represents significant pathway additional loss elements, phosphorus, mature systems. evidence presented here shows biogeochemical perturbations enhanced fluxes continue decades following deforestation pasture. Copyright © 2006 John Wiley & Sons, Ltd.