Scenario analysis for reduction of effluent load from an agricultural area by recycling the run-off water

• Published in: Water Science & Technology Vol. 49; no. 3; pp. 55 - 62
• Main Authors: Shiratani, E, Yoshinaga, I, Feng, Y, Hasebe, H
• Format: Journal Article Conference Proceeding
• Language: English
• Published: England IWA Publishing 01.01.2004
• Subjects: Agricultural management; Agricultural runoff; Agriculture; Canals; Computer simulation; Conservation of Natural Resources; Drainage systems; Ecosystem; Effluents; Irrigation systems; Load distribution; Mathematical models; Nitrogen; Nitrogen - isolation & purification; Oryza; Recycling; Reduction; Reservoirs; Runoff; Water Movements; Water Pollution - prevention & control; Water Purification - methods; Wetlands
• ISBN: 184339460X; 9781843394600
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2004.0162

We reviewed rates of nitrogen (N) removal in paddy fields and wetlands. Then we developed a numerical model to simulate N flow in an agricultural paddy field area and analyzed scenarios for recycling the agricultural run-off, including field drainage, from an agricultural area with an irrigation/drainage system. In it, we considered N removal in paddy fields, a regulating reservoir, and canals. The review showed that the rate constant for N removal in paddy fields and wetlands was 0.025 m/d under natural conditions and 0.01 m/d under dark conditions. The scenario analysis of recycling paddy field run-off within the model area indicated that a large amount of the effluent load occurred during the transplanting period and that recycling could reduce the effluent N load. The effluent N load would be equal to the inflowing N load at a 48% recycling rate. In this scenario, paddy fields accounted for most of the reduction in the effluent N load, and the mean removal rates per unit area of paddy field and regulating reservoir were 53.6 g ha(-1)d(-1) and 222.6 g ha(-1)d(-1) , respectively.