TY - JOUR
T1 - Floodplain connection buffers seasonal changes in urban stream water quality
AU - Ledford, Sarah H.
AU - Lautz, Laura K.
N1 - Publisher Copyright:
© 2014 John Wiley & Sons, Ltd.
PY - 2015/3/15
Y1 - 2015/3/15
N2 - Urban streams in the Northeastern United States have large road salt inputs during the winter, increased nonpoint sources of inorganic nitrogen and decreased short-term and permanent storage of nutrients. Restoration activities that re-establish connection between streams and riparian environments may be effective for improving urban stream water quality. Meadowbrook Creek, a first-order stream in Syracuse, NY, provides a unique setting to explore impacts of stream-floodplain connection because it flows along a negative urbanization gradient, from channelized and armoured headwaters to a broad, vegetated floodplain with a riparian aquifer. In this study, we investigated how reconnection to groundwater and introduction of riparian vegetation impacted urban surface water chemistry by making biweekly longitudinal surveys of stream water chemistry in the creek from May 2012 until June 2013. We used multiple methods to measure groundwater discharge rates along the creek. Chloride concentrations in the upstream, disconnected reach were influenced by discharge of road salt during snow melt events and ranged from 161.2 to 1440mg/l. Chloride concentrations in the downstream, connected reach had less temporal variation, ranging from 252.0 to 1049mg/l, because of buffering by groundwater discharge, as groundwater chloride concentrations ranged from 84.0 to 655.4mg/l. In the summer, there was little to no nitrate in the disconnected reach because of limited sources and high primary productivity, but concentrations reached over 1mgN/l in the connected reach because of the presence of riparian vegetation. During the winter, when temperatures fell below freezing, nitrate concentrations in the disconnected reach increased to 0.58mgN/l but were still lower than the connected reach, which averaged 0.88mgN/l. Urban stream restoration projects that restore floodplain connection may impact water quality by storing high salinity road run-off during winter overbank events and discharging that water year-round, thereby attenuating seasonal fluctuations in chloride. Contrary to prior findings, we observed that floodplain connection and riparian vegetation may alter nitrate sources and sinks such that nitrate concentrations increase longitudinally in connected urban streams.
AB - Urban streams in the Northeastern United States have large road salt inputs during the winter, increased nonpoint sources of inorganic nitrogen and decreased short-term and permanent storage of nutrients. Restoration activities that re-establish connection between streams and riparian environments may be effective for improving urban stream water quality. Meadowbrook Creek, a first-order stream in Syracuse, NY, provides a unique setting to explore impacts of stream-floodplain connection because it flows along a negative urbanization gradient, from channelized and armoured headwaters to a broad, vegetated floodplain with a riparian aquifer. In this study, we investigated how reconnection to groundwater and introduction of riparian vegetation impacted urban surface water chemistry by making biweekly longitudinal surveys of stream water chemistry in the creek from May 2012 until June 2013. We used multiple methods to measure groundwater discharge rates along the creek. Chloride concentrations in the upstream, disconnected reach were influenced by discharge of road salt during snow melt events and ranged from 161.2 to 1440mg/l. Chloride concentrations in the downstream, connected reach had less temporal variation, ranging from 252.0 to 1049mg/l, because of buffering by groundwater discharge, as groundwater chloride concentrations ranged from 84.0 to 655.4mg/l. In the summer, there was little to no nitrate in the disconnected reach because of limited sources and high primary productivity, but concentrations reached over 1mgN/l in the connected reach because of the presence of riparian vegetation. During the winter, when temperatures fell below freezing, nitrate concentrations in the disconnected reach increased to 0.58mgN/l but were still lower than the connected reach, which averaged 0.88mgN/l. Urban stream restoration projects that restore floodplain connection may impact water quality by storing high salinity road run-off during winter overbank events and discharging that water year-round, thereby attenuating seasonal fluctuations in chloride. Contrary to prior findings, we observed that floodplain connection and riparian vegetation may alter nitrate sources and sinks such that nitrate concentrations increase longitudinally in connected urban streams.
KW - Chloride
KW - Groundwater discharge
KW - Nitrate
KW - Road salt
KW - Surface water-groundwater interaction
KW - Urban hydrology
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U2 - 10.1002/hyp.10210
DO - 10.1002/hyp.10210
M3 - Article
AN - SCOPUS:84906259577
SN - 0885-6087
VL - 29
SP - 1002
EP - 1016
JO - Hydrological Processes
JF - Hydrological Processes
IS - 6
ER -