INFLUENCE OF RICE PADDY OPERATION ON RIVER FLOW RATE -CASE STUDY IN THE LOWER REACH OF THE EAI RIVER, MIYAGI PREFECTURE-

Abstract

Irrigation process for paddy field and its influence on river flow rate was investigated in the lower reach of the Eai River which is one of the representative rice producing areas in Tohoku district. The water stage, intake rate and outflow rate was measured continuously in a paddy field through the whole irrigation period from the puddling stage to the final drying stage in 2014. After the water balance analysis including the terms of evapotranspiration, infiltration and rainfall, the empirical rule for rice paddy operation was formulated to predict the response of paddy field to weather condition. The model performance was examined and verified for condition in 2013.