INFLUENCE OF HIGH-TURBID INFLOW ON WATER SUPPLY IN THE SHIHMEN RESERVOIR

摘要

The Shihmen reservoir is a multi-functional reservoir and its functions include irrigation, waterrnsupply, hydroelectric power, flood prevention and sightseeing. The major allocation of registeredrnwater rights for irrigation and water supply are 43.28% and 20.96%, respectively. In 2004,rnTyphoon Aere attacked Taiwan and generated more than 973 mm rainfall within 4 days in thernwatershed of the Shihmen reservoir. Highly turbid inflows affected the water supply systemrnseriously. Sediment concentration of the inflow water in the Typhoon Aere rose to 242,000rnNephelometric Turbidity Unit (NTU) and was far-exceeded water treatment capacity which canrnonly handle 6,000 NTU. Such high sediment concentration caused a loss of water supply for twornweeks in the Taoyuan area. A three-stage water intake has been designed to divert lowerrnturbidity water at various water levels. Based on field measured data, a 3D numerical model isrnemployed to simulate velocity and concentration phenomenon in the reservoir to providernguidance for operation timing for allocating public water supply and irrigation water.