From April 1 to 8, 15 to 16, 19 to 22, 29 to 30 and from May 2 to 5, the whole province of Hunan, especially the southern Hunan region, suffered five rounds of heavy rainfall in a row, and the water level of some rivers in the main tributaries of the Xiangjiang River, the Beijiang tributaries of the Pearl River basin and Dongting Lake rose greatly, and the rainfall was 70% higher than the average of the same period of the previous year.
In the face of successive flood challenges, the Hunan Provincial Department of Water Resources, under the careful guidance of the Ministry of Water Resources and the strong leadership of the Provincial Party Committee and the Provincial Government, resolutely assumed the responsibility of flood control, made many special arrangements for heavy rainfall prevention and response, anchored the "four noes" goal, penetrated the "four feelings" defense, strengthened the "four precautions" measures, tightened the "four chains", and grasped the rainwater process in the whole process in accordance with the scheduling idea of "pre-discharge before the rain, flood control in the rain, and prevention and control after the rain", and made every effort to ensure the safety of flood control.
Pre-discharge before rain fully empowered
Before the rainfall process, the coordination and cooperation of water conservancy, meteorology, electric power and other departments should be strengthened, and the pre-discharge of reservoirs should be dispatched in advance to improve the flood control capacity of the basin by combining factors such as rainfall forecast information, bottom water in the basin, and adjustable storage capacity of each reservoir. In the forecast heavy rainfall area, the two large provincial diversion reservoirs in Shuangpai and Ouyanghai have a cumulative pre-discharge capacity of nearly 374 million cubic meters in April, which is nearly 374 million cubic meters more than the designed flood control reservoir capacity, which is five times the reserved rated flood control storage capacity. Among them, 89 million cubic meters from April 1 to 8 and 130 million cubic meters from 19 to 22 were added.
Flood discharge from Ouyang Sea Reservoir
Flood control in the rain and precise energy release
In the process of rainwater and flooding, the key parameters such as water level, flow, rainfall and flood control of important reservoirs covered by heavy rainfall in the basin are collected hour by hour, and the storage capacity is always used in the critical period of reducing the flood level and accelerating the water retreat for the downstream by relying on the information dispatching system, precise tracking and precise scheduling. In the process of flood control, the dispatching strategy of "three safety and stability" (i.e., safe and stable pre-discharge flow, safe and stable peak shaving flow, and safe and stable flood control flow) was formulated.
In the process of facing the heavy rain and flood in southern Hunan from the 19th to the 22nd, the Shuangpai reservoir was stably pre-discharged with 800 seconds of cubic meters of outflow before the rain, and the flood was stopped in 1200 seconds of cubic meters in the rain, and then the peak was accurately cut with 2400 seconds of cubic meters of outbound flow (2500 seconds of super-alarm flow of downstream Shuangpai station), and the gate was opened and closed stably in the whole process, with a maximum inbound flow of 3617 seconds cubic meters, a maximum outbound flow of 2480 cubic meters, and a peak shaving rate of 31% for the downstream peak shaving of 1137 cubic meters, and a peak shaving rate of 31%, which avoided the upstream road county, Super-alert floods occurred along the downstream Shuangpai and the middle and upper reaches of the Xiangjiang River, and the flood prevention and disaster reduction benefits of the reservoir were fully demonstrated. During the five rounds of heavy rainfall, the province's 11 provincial large-scale reservoirs have a cumulative flood storage capacity of 4 billion cubic meters, making every effort to release guardian energy for the safety of people's lives and property downstream.
Shuangpai reservoir flood discharge
Scientific energy storage after rain prevention and control
After the rainstorm process, the reservoir dispatching strategy is adjusted on a rolling basis according to the next round of rainfall forecast, and when the rainfall process is forecast to occur within 5 days in the future, it will be transferred to the pre-rain pre-discharge stage. When no significant rainfall is forecast in the next 5 days, the reservoir will scientifically maintain the water level and improve the comprehensive benefits of power generation, irrigation and water supply. Since the beginning of the flood season, the province's 11 provincial reservoirs have increased their storage by 1.01 billion cubic meters, providing sufficient energy for the province's high-quality development.
As of May 8, there have been no major dangers in all kinds of reservoirs in the province, and large backbone reservoirs such as Wuqiang River and Zhexi have successfully completed the flood control task in the river basin, successfully protecting the safety of people's lives and property.
Source: Hunan Provincial Department of Water Resources
Author: Wang Lin, Hu Ke, Wending