This paper aimed to evaluate the water balance and to analyze the water quality of a paddy field irrigation system in low lying area. The water balance and concerning components were analyzed using a complex tank model consisted of paddy tank and drainage tank. The unknown return flow parameters such as outflow terms from paddy fields and from drainage canal were able to be predicted using the tank model. The existence of the return flow in the system improves the efficiency of water use, but may have severe impacts on water quality in creek network. Therefore, the water quality is also necessary to be examined. The status of water quality was clarified by evaluating both the net substance concentration and the net effluent load in the paddy irrigation system. The paddy fields showed the function of purification for total nitrogen (TN) except at periods of fertilizer application. Furthermore, the paddy fields had a tendency to follow the load form for electric conductivity (EC) and chemical oxygen demand (COD). The formulas for predicting the net effluent loads in the area were also proposed in this paper.
|Number of pages
|Journal of the Faculty of Agriculture, Kyushu University
|Published - Nov 1998
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science