Hot dry summer

Over a month has passed since our last fieldwork at Takiya River. This summer has turned out to be very hot and dry, and river levels are very low throughout Niigata. The hydrograph above shows there has only been two or three rainfall events in the past 5 weeks! There are two very long periods of flow recession without any rainfall. The influence of the forest vegetation evapotranspiration on the low flows can be seen by the daily fluctuations over the past two weeks.

Although this is high season for leeches and horseflies, we were only hassled by a few of the latter. The very dry conditions this year have kept the number of insects to a minimum.

Of particular note is that the authorities have removed all the fallen trees from the river below the gauging point. About 10 fallen cedar trees in total were removed. Apart from the caterpillar tracks on the river bank, the negative impacts on the river environment seem to be minimal.



Taking a discharge measurement (stage = 42cm, water temperature = 21 C)

All the fallen trees have been removed from the river below the gauging point

Uonogawa field trip

Gauging station on the Uonogawa at Horinouchi (A = 1400 km2)

Currently Team Hydrology are working with data from the Uonogawa River in the upper reaches of the Shinano River. This river basin has especially heavy snowpack in winter and very rich water resources which are used downstream throughout the Niigata Plain for rice paddy agriculture.

Today we visited several hydrometric monitoring stations that measure streamflow, precipitation, and snowpack in the basin, as well as the major dam site within the basin at Kuromatagawa Dam. When using data for hydrological simulation, it is important to see first-hand where and how the data has been collected!

Amedas weather station at Irihirose where snowpack exceeds 3m in winter

 

Snow cat machine at Irihirose

Kuromatagawa Dam

Shinano River gauging station at Ojiya (largest river discharge in Japan!)