Study and Application of Emergency Water Dispatching of Jialing River

In recent years, due to the re-occurrence of extreme weathers and the water consumption increasing, Jialing River Basin is suffering drought disasters with characteristics of high frequency and aggravating influence, which seriously impacts on the urban water supply safety. A special study was carried out with respect to the drought status quo and the demand on emergency water supply, and the results are mainly in two aspects as follows. One is the determination for the drought warning water level / flow. The drought warning water level / flow is a threshold to characterize the reduction of the water level / flow to a certain degree that the masses life, the industrial and agricultural production, and the ecological environment are affected or interrupted which the drought mitigation measures such as the emergency water diversion needed. An example was taken in Beibei hydrological station in Chongqing Municipality. First, the minimum controlled water flow of Beibei station which can satisfy the urban water demand in Chongqing was confirmed. Secondly, according to the confluence proportion of the tributary to the main stream, the limited water levels / flows for each dispatch nodes in the upstream of Beibei station were deduced. Finally, a three-level warning indicator was defined based on these limits. Another result is the strategy of the reservoir operation function. According to the regulation/storage capacity and water supplementary function of the reservoirs along the main stream or tributaries of Jialing River, the reservoirs are divided into three categories: 1) Class A, has large storage and great regulation capacity, which was taken as the primary source for emergency water dispatching; 2) Class B, has a certain storage / regulation capacity, which was taken as the supplementary water source of Class A reservoirs with the compensation adjustment for emergency water dispatching; 3) Class C, basically has no regulation/storage capacity, mainly serving for the run-off power stations, which was taken coordinated function during emergency water dispatching. According to the study results, we can make more scientific, efficient and orderly organization and implementation for water dispatching work. The Office of State Flood Control and Drought Relief Headquarters (SFDH) organized and drew up “Jialing River Water Dispatch Plan” (hereinafter referred to as “Plan”) according to the special study results. The Plan put forward the principle and technique framework of the emergency water dispatching. In 2007 February, the water level in Beibei station was only 172.06 meters which was the lowest one since the hydrological data began to record in 1939. And the 3 of 7 intakes water supply companies in urban district of Chongqing were unable to take water. Besides, the daily water supply reduced up to 55,000 cubic meters. The urban water supply safety was seriously impacted. Aiming at the severe drought situation, the SFDH abided by the Plan to start the emergency response timely and transfer water from upper reservoirs to Chongqing scientifically, which effectively ensured the water supply safety for about 8 million people in the urban district of Chongqing.