HR: 0800h
AN: H51B-0449    [Abstracts]
TI: Watershed Scale Observation and Analysis of Stream Temperatures in the Ibogawa River, Japan
AU: * Miyamoto, H
EM: miyamo@kobe-u.ac.jp
AF: Department of Civil Engineering, Kobe University, Rokkodai 1-1, Nada, Kobe, 657-8501, Japan
AU: Michioku, K
EM: michioku@kobe-u.ac.jp
AF: Department of Civil Engineering, Kobe University, Rokkodai 1-1, Nada, Kobe, 657-8501, Japan
AB: In this study, we reported monitoring results of stream temperatures in the Ibogawa river basin, Hyogo prefecture, Japan. We, then, examined relative contributions of each component in a theoretical solution of stream temperature conservation equation. The solution of the thermal energy equation was derived with the method of characteristics and Taylor-series approximation. In the Ibogawa River, 27 observation points were set up in order to sequentially monitor the stream temperatures in the whole watershed extent. Spatial distributions of the monthly averaged stream temperatures, spectral characteristics of the temperature time series, and one-day moving averaged temperatures with meteorological and hydrological data were discussed in detail. The spatial distributions of the monthly averaged stream temperatures showed their increase behavior from the upper stream to the river mouth. Comparison of the temperature time-series between the main stream and tributary indicated much difference in their temperature change. Moreover, the Spectral analysis showed that the diurnal fluctuation of the solar radiation affected very much on thermal energy balance in the whole river system. It was also found that the temporal fluctuations longer than the diurnal fluctuation were formed mainly due to the changes of meteorological and hydrological conditions, i.e., the sunlight duration, precipitation, and the river discharge. Then, we examined relative contributions of each component in the thermal energy equation in terms of different time scales. It was found out that the equilibrium temperature, i.e., the solar radiation influence, was of much importance for the monthly averaged stream temperatures in the watershed, while the convection and unsteady terms in the thermal energy equation, i.e., hydrological influence, emerged to be significant in the shorter, less than the 5-day, averaged stream temperatures.
DE: 0496 Water quality
DE: 1860 Streamflow
DE: 1871 Surface water quality
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting