Air and water temperature changes after weirs construction in medium size river

Weirs had been constructed in medium size river (Nakdong river) in Korea, and air and water temperature have been monitored at 3 weirs - Gumi, Chilgok, Gangjeong - in oder to monitor for how they have been changed after construction. First, in water temperatures monitored at 0cm, -50cm, and ?100cm, a monthly means were always higher than air temperatures at 10m, and no significant difference are shown for three depths i.e., water temperature are homogeneous with the depth up to 100cm. Both air and water temperatures were higher with lower latitude and this characteristic was cleared in water temperature with seasons i.e., a difference of water temperature was larger in fall and winter. The correlation between air and water temperature was not noticeable in real time or daily average, but in view of weeks, months, and years, the correlation coefficients showed above 0.8, respectively. In hourly mean variation with each month, both air and water temperature showed a daily curve. Moreover, air temperature had reached to the minimum 1 hour earlier than that of water temperature, however, it raised to the maximum about 2 hours later. Finally, we set eight categories in order to illustrate an energy exchange between air and water. 72~81% of total cases was that air temperature showed higher than water temperature, and 14~19% of them was reversed