Publication Date:
2014-03-31
Description:
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, New York, provides a unique setting to explore impacts of stream-floodplain connection because it flows along a negative urbanization gradient, from channelized and armored 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 bi-weekly 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 1440 mg/L. Chloride concentrations in the downstream, connected reach had less temporal variation, ranging from 252.0 to 1049 mg/L, due to buffering by groundwater discharge, as groundwater chloride concentrations ranged from 84.0 to 655.4 mg/L. In the summer, there was little-to-no nitrate in the disconnected reach due to limited sources and high primary productivity, but concentrations reached over 1 mg N/L in the connected reach due to the presence of riparian vegetation. During the winter, when temperatures fell below freezing, nitrate concentrations in the disconnected reach increased to 0.58 mg N/L, but were still lower than the connected reach, which averaged 0.88 mg N/L. Urban stream restoration projects that restore floodplain connection may impact water quality by storing high salinity road runoff during winter overbank events and discharging that water year-round, thereby attenuating seasonal fluctuations in chloride. Contrary to prior findings, we observed floodplain connection and riparian vegetation may alter nitrate sources and sinks such that nitrate concentrations increase longitudinally in connected urban streams. This article is protected by copyright. All rights reserved.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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