ARS | Publication request: Runoff losses of suspended sediment, nitrogen, and phosphorus from a small watershed in Korea

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2010
Publication Date: March 15, 2010
Repository URL: http://hdl.handle.net/10113/42858
Citation: Chun, J.A., Cooke, R.A., Kang, M.S., Choi, M., Timlin, D.J., Park, S.W. 2010. Runoff losses of suspended sediment, nitrogen, and phosphorus from a small watershed in Korea. Journal of Environmental Quality. 39:981-990.

Interpretive Summary: Nitrogen and phosphorous are applied as fertilizers to almost all agricultural fields. These nutrients may be lost from the soil with suspended sediment in runoff which may result in environmental or health problems. However, it is not easy to reduce runoff losses of those nutrients and suspended sediment, due to seasonal variations in rainfall and soil concentrations. In this research, the relationships of runoff losses of suspended sediment and nutrients were developed. Annual and monthly runoff losses of the nutrients and suspended sediment from a small agricultural watershed were estimated using these relationships. Most of the sediments and nutrients transported in runoff left the watershed between April and September, thus cost-efficient strategies can be established by focusing on this period. These results can be used to improve water quality by providing more efficacious remediation practices. Water conservation practitioners, Environmental engineers, Agricultural engineers and Agricultural extension specialists will benefit from this research.

Technical Abstract: The objectives of this study were to develop annual and seasonal load-discharge relationships for Suspended Sediment (SS), Total Nitrogen (TN), and Total Phosphorus (TP) losses in runoff from a small mixed land use watershed, and to use these relationships to explicate the annual and monthly patterns of losses of these components. Data from 1996 to 2004 were used to develop load-discharge relationships for SS, TN, and TP at the HP#6 watershed, a sub-watershed of the Balhan reservoir watershed, located in Bongdam-myun and Paltan-myun, Gyeongi-do, Korea. Both the standard least squares (LS) curve fitting and the S-estimation procedures were used to fit power functions to the data collected over this time period. The fitted load-discharge relationships are indicative of seasonal variations in SS, TN, and TP losses in runoff from HP#6. The exponents of the fitted power functions for TN and TP in the fall, for TP in summer season and for SS in all seasons, are greater than 1, indicating that the concentrations of these species increase as flow rate increases. Most of the SS, TN, and TP transported in runoff left the watershed between April and September, thus cost-efficient strategies can be established by focusing on this period. Further study of the seasonal variations is required for a better characterization of seasonal losses of SS, TN, and TP in runoff from the HP#6 watershed.