Abstract:

By traditional method of monitoring reservoir water temperature, the concrete temperature on the upstream surface of dam (which is measured by point thermometer inside the concrete) is taken as the water temperature. Errors are caused and the gauging points are limited. On the contrary, the distributed optical fiber (DOF) temperature measuring temperature system based on Raman scattering has resistance to EMI (electromagnetic interference), resistance to corrosion, electric insulation, high sensitivity, low cost, and can implement continuous spatial distributed measurement. We have applied this measurement system to the Three Gorges reservoir water temperature monitoring and studied its principle from perspectives of Optical Time Domain Reflectrometry(OTDR), Raman Scattering and scattering-light demodulation. Monitoring results show that the reservoir water temperature in front of the Three Gorges dam varies with atmospheric temperature with no obvious stratification along the water depth direction. The maximum average temperature is nearly 27℃ in August and the minimum is 10℃ in February.  

Key words: Raman scattering, distributed optical fiber, OTDR, reservoir water temperature