TY - JOUR
T1 - Implications of hydrologic connectivity between hillslopes and riparian zones on streamflow composition
AU - Von Freyberg, Jana
AU - Radny, Dirk
AU - Gall, Heather E.
AU - Schirmer, Mario
N1 - Funding Information:
This study was funded by the Swiss National Science Foundation (SNF, Projects No. 200021_129735 and 200020_143688 ). We would like to thank B. Kianfar, I. Lehner, R. Mégroz and A. Raffainer for their support during fieldwork and two anonymous reviewers for their comments. The group of S. Seneviratne (Land-Climate-Dynamics), Institute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology Zurich (ETHZ) provided data of the meteorological station Büel (rainfall, evapotranspiration) and gauging station Upper Rietholzbach (URHB). H.E. Gall was supported by the Penn State Institutes of Energy and the Environment and The Pennsylvania State University. Additional support was provided by the Competence Center Environment and Sustainability (CCES) of the ETH domain in the framework of the RECORD (Assessment and Modeling of Coupled Ecological and Hydrological Dynamics in the Restored Corridor of a River (Restored Corridor Dynamics)) and RECORD Catchment projects.
PY - 2014/11/15
Y1 - 2014/11/15
N2 - Hydrological responses in mountainous headwater catchments are often highly non-linear with a distinct threshold-related behavior, which is associated to steep hillslopes, shallow soils and strong climatic variability. A holistic understanding of the dominant physical processes that control streamflow generation and non-linearity is required in order to assess potential negative effects of agricultural land use and water management in those areas. Therefore, streamflow generation in a small pre-Alpine headwater catchment (Upper Rietholzbach (URHB), ~ 1 km2) was analyzed over a 2-year period by means of rainfall-response analysis and water quality data under explicit consideration of the joint behaviors of climate forcing and shallow groundwater dynamics. The runoff coefficients indicate that only a small fraction of the total catchment area (1-26%) generates streamflow during rainfall events. Hereby, the valley bottom areas (riparian zones) were the most important event-water source whereas only the lower parts of the hillslopes became hydrologically connected to the river network with higher antecedent moisture conditions. However, a distinct threshold-like behavior could not be observed, suggesting a more continuous shift from a riparian-zone to a more hillslope-dominated streamflow hydrograph. Regular manure application on the hillslopes in combinations with lateral hillslope groundwater flux and long groundwater residence times in the riparian zones resulted in a higher mineralization (e.g., total phosphorous) and significant denitrification in the valley bottom area. Despite the important role of the riparian zones for event-flow generation in the URHB, their nutrient buffer capacity is expected to be small due to the low permeability of the local subsurface material. The findings of this integrated analysis are summarized in a conceptual framework describing the hydrological functioning of hillslopes and riparian zones in the URHB.
AB - Hydrological responses in mountainous headwater catchments are often highly non-linear with a distinct threshold-related behavior, which is associated to steep hillslopes, shallow soils and strong climatic variability. A holistic understanding of the dominant physical processes that control streamflow generation and non-linearity is required in order to assess potential negative effects of agricultural land use and water management in those areas. Therefore, streamflow generation in a small pre-Alpine headwater catchment (Upper Rietholzbach (URHB), ~ 1 km2) was analyzed over a 2-year period by means of rainfall-response analysis and water quality data under explicit consideration of the joint behaviors of climate forcing and shallow groundwater dynamics. The runoff coefficients indicate that only a small fraction of the total catchment area (1-26%) generates streamflow during rainfall events. Hereby, the valley bottom areas (riparian zones) were the most important event-water source whereas only the lower parts of the hillslopes became hydrologically connected to the river network with higher antecedent moisture conditions. However, a distinct threshold-like behavior could not be observed, suggesting a more continuous shift from a riparian-zone to a more hillslope-dominated streamflow hydrograph. Regular manure application on the hillslopes in combinations with lateral hillslope groundwater flux and long groundwater residence times in the riparian zones resulted in a higher mineralization (e.g., total phosphorous) and significant denitrification in the valley bottom area. Despite the important role of the riparian zones for event-flow generation in the URHB, their nutrient buffer capacity is expected to be small due to the low permeability of the local subsurface material. The findings of this integrated analysis are summarized in a conceptual framework describing the hydrological functioning of hillslopes and riparian zones in the URHB.
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U2 - 10.1016/j.jconhyd.2014.07.005
DO - 10.1016/j.jconhyd.2014.07.005
M3 - Article
C2 - 25106837
AN - SCOPUS:84908458001
SN - 0169-7722
VL - 169
SP - 62
EP - 74
JO - Journal of Contaminant Hydrology
JF - Journal of Contaminant Hydrology
ER -
