Autumn recession flow

Stage = 55.5cm, Ta = 8.7C, Tw = 12.4C

The hydrograph below shows and long period of recession flow (6 days) during which the weather was dry, followed by a medium size peak due to a rainfall event. Notice how the flow recession is steep right after the peak, becoming more gradual as the water level falls.

Dragon-fly season

Stage = 51cm, Ta = 8.8C, Tw = 11.6C

Dragon-fly season in fall brings some perfect weather for fieldwork. The air was dancing with red dragon-flies or "aka tonbo" as they are known in Japanese. I introduced two new students to Takiya River field site, and showed them how to make a discharge measurement. Our work went very smoothly - I think they will make a great team.

You can see in the hydrograph below that September and October has brought some periods of heavy rain, with two flood peaks of around 90cm. See how the summer low-flow season came to an end around 19th September, and how the base flows have increased in recent weeks. This is due to the frequent rain showers, and the much cooler temperatures and reduced evapotranspiration (ET) which comes with the autumn season.