TY  - JOUR
A1  - Zimmermann, Beate
A1  - Zimmermann, Alexander
A1  - Turner, Benjamin L.
A1  - Francke, Till
A1  - Elsenbeer, Helmut
T1  - Connectivity of overland flow by drainage network expansion in a rain forest catchment
JF  - Water resources research
N2  - Soils in various places of the Panama Canal Watershed feature a low saturated hydraulic conductivity (K-s) at shallow depth, which promotes overland-flow generation and associated flashy catchment responses. In undisturbed forests of these areas, overland flow is concentrated in flow lines that extend the channel network and provide hydrological connectivity between hillslopes and streams. To understand the dynamics of overland-flow connectivity, as well as the impact of connectivity on catchment response, we studied an undisturbed headwater catchment by monitoring overland-flow occurrence in all flow lines and discharge, suspended sediment, and total phosphorus at the catchment outlet. We find that connectivity is strongly influenced by seasonal variation in antecedent wetness and can develop even under light rainfall conditions. Connectivity increased rapidly as rainfall frequency increased, eventually leading to full connectivity and surficial drainage of entire hillslopes. Connectivity was nonlinearly related to catchment response. However, additional information on factors such as overland-flow volume would be required to constrain relationships between connectivity, stormflow, and the export of suspended sediment and phosphorus. The effort to monitor those factors would be substantial, so we advocate applying the established links between rain event characteristics, drainage network expansion by flow lines, and catchment response for predictive modeling and catchment classification in forests of the Panama Canal Watershed and in similar regions elsewhere.
KW  - connectivity
KW  - overland flow
KW  - stormflow
KW  - suspended sediment
KW  - phosphorus
KW  - drainage network expansion
Y1  - 2014
U6  - https://doi.org/10.1002/2012WR012660
SN  - 0043-1397
SN  - 1944-7973
VL  - 50
IS  - 2
SP  - 1457
EP  - 1473
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Neill, Christopher
A1  - Coe, Michael T.
A1  - Riskin, Shelby H.
A1  - Krusche, Alex V.
A1  - Elsenbeer, Helmut
A1  - Macedo, Marcia N.
A1  - McHorney, Richard
A1  - Lefebvre, Paul
A1  - Davidson, Eric A.
A1  - Scheffler, Raphael
A1  - Figueira, Adelaine Michela e Silva
A1  - Porder, Stephen
A1  - Deegan, Linda A.
T1  - Watershed responses to Amazon soya bean cropland expansion and intensification
JF  - Philosophical transactions of the Royal Society of London : B, Biological sciences
N2  - The expansion and intensification of soya bean agriculture in southeastern Amazonia can alter watershed hydrology and biogeochemistry by changing the land cover, water balance and nutrient inputs. Several new insights on the responses of watershed hydrology and biogeochemistry to deforestation in Mato Grosso have emerged from recent intensive field campaigns in this region. Because of reduced evapotranspiration, total water export increases threefold to fourfold in soya bean watersheds compared with forest. However, the deep and highly permeable soils on the broad plateaus on which much of the soya bean cultivation has expanded buffer small soya bean watersheds against increased stormflows. Concentrations of nitrate and phosphate do not differ between forest or soya bean watersheds because fixation of phosphorus fertilizer by iron and aluminium oxides and anion exchange of nitrate in deep soils restrict nutrient movement. Despite resistance to biogeochemical change, streams in soya bean watersheds have higher temperatures caused by impoundments and reduction of bordering riparian forest. In larger rivers, increased water flow, current velocities and sediment flux following deforestation can reshape stream morphology, suggesting that cumulative impacts of deforestation in small watersheds will occur at larger scales.
KW  - soya beans
KW  - watersheds
KW  - nitrogen
KW  - phosphorus
KW  - soil
Y1  - 2013
U6  - https://doi.org/10.1098/rstb.2012.0425
SN  - 0962-8436
SN  - 1471-2970
VL  - 368
IS  - 1619
PB  - Royal Society
CY  - London
ER  -