STUDY ON CHANGING IN RIVER WATER TEMPERATURE IN KYUSYU REGION

Abstract

 This study was carried out to grasp the actual condition of long term changes in the river water temperture in the Kyushu region and considered the relationship with factors. The water temperature rise rate (℃ / year) was obtained by using the water temperature data of the hydrological water quality database from 1971 to 2016. The average value of them was 0.034 ℃ / year, significance upward trend was detected at 35 of 132 sites, and the maximum value was 0.109℃/ year. The water temperature rise rate tended to be high in the water system with high population density or the water system with small annual average flow rate.In addition, the relation between the water temperature rise rate and the position of the weir was analyzed, it was shown that the weir within 2000m upstream from an observation point had an influence on the water temperature rise on the downstream side. At these points, the water temperature rise rate was particularly high in from May to November, and the average value in each month were 0.060 to 0.087℃ / year.