1998 Volume 11 Issue 12 Pages 695-702
Needless to say, how to conserve and, desirably, improve water quality of Lake Biwa is an extremely important problem to be solved. This paper is concerned with reduction of pollutant load discharged from paddy fields. In Shiga Prefecture around Lake Biwa, the rice crop is dominant in the agriculture, and the water discharged from each paddy field flows into Lake Biwa through drainage canals. Then from the viewpoint that the outlet of each paddy field is a source of pollution, at a paddy field of 30 ares, the authors examined in detail about the input/output of water and the outflow of nutrients for three years.
Based upon the results of the examination, this paper develops a model for describing input/output of water at a paddy field, and simulates and evaluates some methods for reducing outflow discharged from a paddy field.