Abstract
The purpose of this work was to investigate the relation between water quality and discharge at rain using an automatic water quality observation equipment in a small mountain stream. Our study area was a tributary of the river Yotsugo in Shiga town, Shiga prefecture. We made two types of investigation. The first (1996.4.4〜6.30) was observed for three months. The interval of the measurement was once an hour. The second(1996.7.7〜7.8)was observed for one day. The interval was once every ten minutes. Results of these investigations were:(1) When discharge increased water temperature rose in accordance with discharge. (2) Some sudden rise of turbidity caused by rain and some kinds of TB-Q hysteresises were found. (3) At least 10 minutes were preferable at measurement interval because the water quality changed in a short time.
