Abstract
The purpose of this study is to clarify the effect of reservoir operation on the flow regime in the lower watershed using numerical simulation. Using the simulated river discharge data, the spectrum characteristics of river discharge data was studied.
As a result of numerical simulation, The spectrum of daily discharges available information was analyzed by using the fast Fourier Transform for daily discharges in Nakhon Sawan city and immediately downstream the Bhumibol reservoir. The river flow in Nakhon Sawan city has a periodic characteristic of 7-days, and the released water from the Bhumibol and Sirikit reservoir' have a periodic characteristic of 7-days. The reservoir operations affected the hydrological cycles considerably. Two large scale reservoirs have been affected to the flow regime in the lower Chao Phraya River basin of Thailand using the historical discharge data. As mentioned above, the river flow regime at least around 400km downstream large scale reservoir could be affected by the reservoir operation.
