Baseflow contribution to nitrate-nitrogen export from a large, agricultural watershed, USA
Journal of Hydrology
By: K. Schilling and Y.-K. Zhang
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Abstract
Nitrate-nitrogen export from the Raccoon River watershed in west-central Iowa is among the highest in the United State and contributes to impairment of downstream water quality. We examined a rare long-term record of streamflow and nitrate concentration data (1972-2000) to evaluate annual and seasonal patterns of nitrate losses in streamflow and baseflow from the Raccoon River. Combining hydrograph separation with a load estimation program, we estimated that baseflow contributes approximately two-thirds (17.3 kg/ha) of the mean annual nitrate export (26.1 kg/ha). Baseflow transport was greatest in spring and late fall when baseflow contributed more than 80% of the total export. Herein we propose a 'baseflow enrichment ratio' (BER) to describe the relation of baseflow water with baseflow nitrate loads. The long-term ratio of 1.23 for the Raccoon River suggests preferential leaching of nitrate to baseflow. Seasonal patterns of the BER identified the strong link between the baseflow nitrate loads and seasonal crop nitrogen requirements. Study results demonstrate the utility of assessing the baseflow contribution to nitrate loads to identify appropriate control strategies for reducing baseflow delivery of nitrate. ?? 2004 Elsevier B.V. All rights reserved.
Suggested Citation
Schilling, K., Zhang, Y., 2004, Baseflow contribution to nitrate-nitrogen export from a large, agricultural watershed, USA: Journal of Hydrology, v. 295, no. 1-4, p. 305-316, https://doi.org/10.1016/j.jhydrol.2004.03.010.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Baseflow contribution to nitrate-nitrogen export from a large, agricultural watershed, USA |
| Series title | Journal of Hydrology |
| DOI | 10.1016/j.jhydrol.2004.03.010 |
| Volume | 295 |
| Issue | 1-4 |
| Year Published | 2004 |
| Language | English |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Hydrology |
| First page | 305 |
| Last page | 316 |