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Influence of Riparian Seepage Zones on Nitrate Variability in Two Agricultural Headwater Streams
Author(s) -
Williams Mark R.,
Buda Anthony R.,
Elliott Herschel A.,
Singha Kamini,
Hamlett James
Publication year - 2015
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/1752-1688.12335
Subject(s) - streams , riparian zone , hydrology (agriculture) , environmental science , base flow , petroleum seep , water quality , streamflow , storm , drainage basin , geology , ecology , oceanography , habitat , geography , computer network , geotechnical engineering , cartography , methane , computer science , biology
Riparian seeps have been recognized for their contributions to stream flow in headwater catchments, but there is limited data on how seeps affect stream water quality. The objective of this study was to examine the effect of seeps on the variability of stream NO 3 ‐N concentrations in FD 36 and RS , two agricultural catchments in Pennsylvania. Stream samples were collected at 10‐m intervals over reaches of 550 ( FD 36) and 490 m ( RS ) on 21 occasions between April 2009 and January 2012. Semi‐variogram analysis was used to quantify longitudinal patterns in stream NO 3 ‐N concentration. Seep water was collected at 14 sites in FD 36 and 7 in RS , but the number of flowing seeps depended on antecedent conditions. Seep NO 3 ‐N concentrations were variable (0.1‐29.5 mg/l) and were often greater downslope of cropped fields compared to other land uses. During base flow, longitudinal variability in stream NO 3 ‐N concentrations increased as the number of flowing seeps increased. The influence of seeps on the variability of stream NO 3 ‐N concentrations was less during storm flow compared to the variability of base flow NO 3 ‐N concentrations. However, 24 h after a storm in FD 36, an increase in the number of flowing seeps and decreasing streamflow resulted in the greatest longitudinal variability in stream NO 3 ‐N concentrations recorded. Results indicate seeps are important areas of NO 3 ‐N delivery to streams where targeted adoption of mitigation measures may substantially improve stream water quality.