constructing the “three lines of defense” for rainwater monitoring and forecasting
2024-09-17
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forward-looking, timely and accurate rain and water monitoring and forecasting information is an important prerequisite and guarantee for flood disaster prevention. heavy rains and floods often come quickly and suddenly, and traditional monitoring and forecasting methods have a short forecast period and low forecast accuracy. general secretary xi jinping emphasized the need to strengthen rain and water monitoring, forecasting and early warning, make up for the shortcomings in disaster early warning monitoring, and make scientific and accurate predictions and forecasts. the third plenary session of the 20th cpc central committee made arrangements for improving the risk monitoring and early warning system.
in order to gain the initiative in flood disaster prevention, it is necessary to build "three lines of defense" for rainfall monitoring and forecasting based on the river basin, shifting from "rain on the ground" monitoring and forecasting to "rain in the cloud" monitoring and forecasting, and from flood monitoring and forecasting at this station to flood evolution and transmission forecasting, forming a complete monitoring and forecasting chain that runs through "clouds, rain and water" and covers "sky, ground, water and engineering", and achieving the effective unity of extending the flood forecast period and improving the accuracy of flood forecasts.
before the 2024 flood season, the beijing section of the yongding river will be the first to build a "three-line defense" for rainwater monitoring and forecasting, effectively unifying the extension of the flood forecast period and the improvement of forecast accuracy. the picture shows a schematic diagram of the "three-line defense" for rainwater monitoring and forecasting. photo courtesy of the ministry of water resources
'first line of defence'
it is composed of meteorological satellites and rain radars plus rainfall forecast models, runoff generation and convergence hydrological models, and flood evolution hydrodynamic models to achieve monitoring and forecasting of "rain in the cloud". meteorological satellite data is analyzed based on river basins, and quantitative forecasts and warnings of heavy rainfall are carried out. rain radars are used to carry out real-time ultra-fine monitoring of liquid water in the near-ground atmosphere and short-term rainstorm warnings. lidar is used to update and extract underlying surface data. the coupling model analyzes and deduces the entire process of flood formation and evolution of "rainfall-runoff generation-confluence-evolution", and forecasts possible floods before rainfall.
'second line of defence'
it is composed of a rain gauge plus a runoff hydrological model and a flood evolution hydrodynamic model, which can monitor "falling rain" and forecast the evolution of floods. by building a modern rain gauge monitoring station network, based on real-time and accurate monitoring of "falling rain", the monitoring and forecasting results of the "first line of defense" are connected, and the coupling model is used to analyze and deduce the "runoff generation-runoff-evolution" process, dynamically adjust the flash flood disaster warning threshold, and forecast the flood process before the flood occurs, while ensuring the forecast period and improving the forecast accuracy.
the third line of defence
it consists of a hydrological station plus a flood evolution hydrodynamic model to monitor and forecast the flood evolution process. by building a modern hydrological monitoring station network, based on real-time and accurate monitoring of changes in water levels, flows and other factors of rivers, lakes and reservoirs, it connects with the monitoring and forecasting results of the "second line of defense" and couples the model to measure and forecast flood evolution. while accurately measuring and reporting floods at the station, the hydrological station forecasts flood evolution information to downstream hydrological stations or sections to achieve rolling transmission forecasts and further improve forecast accuracy.
in recent years, the water conservancy department has carried out a series of exploratory practices in the construction of rain and water monitoring and forecasting systems. in terms of hardware, it actively promotes the application of satellite remote sensing, drones, ultrasound, radar, video analysis and other technologies, and realizes the integration of "sky, ground, water and engineering" from the previous monitoring mode based on fixed sites and sections. the ministry of water resources carried out a pilot construction of a modern rain and water monitoring and forecasting system in beijing, and networked and built three domestic phased array water conservancy rain measurement radars, realizing the ultra-fine grid monitoring and forecasting of the beijing section of the yongding river basin and the "rain in the cloud" in the main urban area of beijing, and equipped with multi-beam underwater topographic survey ships, drones equipped with laser radars, side-scan radars and other new equipment to comprehensively improve the rain and water monitoring perception capabilities. in terms of software, it actively promotes the research and development and application of mathematical models for analysis and calculation based on modern hydrological information perception and monitoring data, and provides medium- and long-term, short-term, and short-term rain and water forecast results for flood defense. during the severe flood in the beijiang river in the pearl river basin this year, the water conservancy department used the "first line of defense" to predict two days in advance that a once-in-50-year severe flood might occur in the beijiang river, and used the "second line of defense" to update the forecast one day in advance that the flood recurrence period would reach once in 100 years. after the flood peak appeared in the main tributaries, the "third line of defense" was used to carry out downstream flood evolution forecasts, providing advanced and accurate decision-making support for the beijiang river flood dispatch.
for more details, please see the article "promoting the modernization of my country's flood control safety system and capacity" by li guoying, secretary of the party leadership group and minister of the ministry of water resources.
(planning: kuang sisi, review: li yanling)
