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Effects of Climatic Variations over 11 Years on Nitrate‐Nitrogen Concentrations in the Raccoon River, Iowa
Author(s) -
Lucey K. J.,
Goolsby D. A.
Publication year - 1993
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1993.00472425002200010005x
Subject(s) - baseflow , streamflow , hydrograph , environmental science , hydrology (agriculture) , nitrate , precipitation , nitrogen , zoology , surface runoff , drainage basin , ecology , geography , chemistry , biology , meteorology , geology , cartography , geotechnical engineering , organic chemistry
Nitrate‐nitrogen (NO 3 ‐N) concentrations at public water‐supply intakes on the Des Moines and Raccoon Rivers in Iowa exceeded the maximum contaminant level (MCL) of 10 mg L −1 for public water supplies established by the USEPA for extended periods of time from March through early August 1990. The excessive NO 3 ‐N levels followed 2 yr of less than normal precipitation in 1988 and 1989. The largest daily NO 3 ‐N load (771 t) transported during the last 17 yr in the Raccoon River occurred in June 1990. The streamflow hydrograph for the Raccoon River for March 1990 prior to seasonal fertilizer application indicates that high NO 3 ‐N concentrations characterize the recession side of the hydrograph. High NO 3 ‐N concentrations in streamflow persisted as streamflow decreased to baseflow conditions. This implies that substantial quantities of NO 3 ‐N were being leached from the soil and transported by subsurface flow during early 1990. A multiple linear‐regression model was developed to predict NO 3 ‐N concentrations in the Raccoon River from readily‐obtainable streamflow and climatic data. The four‐variable model explained about 70% of the variability in the concentration of NO 3 ‐N. The mean streamflow for the previous 7‐d period accounted for about 50% of the total variability.