Reflections on the dam-break event of Zhumadian Reservoir

It is understood that the forecaster of the Central Meteorological Observatory at that time only drew the rainfall of 100 mm in this area, because there was no scientific understanding at that time, and it was impossible to draw a very accurate conclusion.

Afterwards, experts analyzed the reasons why the "75.8" rainstorm could not be accurately predicted, and thought that: firstly, the path of "7503" typhoon was too secret, which broke the law of large-scale energy release of typhoons in inland areas, making people unprepared and hard to prevent; Secondly, forecasters are not experienced enough, and New China has not been established for a long time. China's meteorological science is still in the stage of exploration and research, and there is no mature experience to learn from. There are many grass-roots meteorological stations that still rely on the old model of air pressure, temperature and humidity curves to see the sky. Thirdly, the observation methods are backward and the communication tools are outdated. After that, meteorologists at all levels adjusted their forecasting ideas, analyzed the causes and defensive countermeasures of local typhoon-caused flood and rainstorm in a joint way, and established a variety of flood-caused rainstorm weather forecasting models.

The concept of dam construction is wrong.

During the period of 1958, Henan summarized the experience of building water conservancy projects in the mountainous areas of the He Sui River Basin: "focusing on storage, focusing on small scale, focusing on self-management by commune teams". Chen Xing, then the chief engineer of Henan Provincial Water Resources Department, immediately expressed his opposition: in plain areas, heavy storage and light discharge will cause serious damage to the water environment-too much surface water will cause waterlogging, too much groundwater will easily lead to waterlogging, and artificially raising the groundwater level will be beneficial to salt accumulation and alkali damage. Waterlogging, waterlogging and alkali are three evils, and the result is unimaginable.

However, Chen Xing's suggestion was ignored, and the experience of "centralized storage" was widely promoted, and it was soon extended to Anhui. In Anhui Province, not only a large number of small reservoirs have sprung up in hilly areas, but also rivers in the Huaihe River Basin have been blocked by a series of "dams", resulting in fatal "intestinal obstruction" in the Huaihe River Basin in the following decades.

Chen Xing is the designer of Suyahu Reservoir in Zhumadian, Henan Province, the largest plain reservoir in the Far East. The construction of the reservoir coincided with the Great Leap Forward. A former leader of the Water Resources Department of Henan Province thought that the original design was too conservative and made several key changes without authorization. For example, he thought that "the gate design was too big", so he cut off seven gates from the original 12 hole drainage gate, leaving only five gates.

At the same time, it encountered the flood diversion gate at the junction of Huaihe River, Henan and Anhui: the gate Kong Yuan was designed with 9 holes according to the displacement of 800 seconds cubic meters, but due to the ideological guidance of "focusing on storage", the hydrological data was artificially reduced and only 7 holes were built; 1959 After the sluice gate is opened, the two holes are manually blocked at 196 1.

The mistake of guiding ideology has not been really reversed for some time, and the tendency of replenishing irrigation, ignoring river regulation and attaching importance to advantages and neglecting disadvantages still persists. By the end of 1960s, there were more than 65,438,000 new reservoirs in Zhumadian. In contrast, the flood discharge capacity of the Hongru River has not been enhanced, but has decreased year by year.

In fact, before the catastrophic flood in August 1975, there was a serious crisis in the upper reaches of the Huaihe River: the river was not well ventilated, the dikes were not firm, and many hidden dangers of "sick dikes" were not removed. What's more, people are not alert to the potential danger of dam failure of large reservoirs such as Banqiao and Shimantan ―― to be precise, the word "dam failure" simply does not exist in people's minds.

People believe too much in the established flood standards such as "once in a hundred years" and "once in a thousand years", and are confident that Shimantan Reservoir can control the once-in-50-year flood and protect itself from the once-in-500-year flood. Banqiao Reservoir can control the flood with a return period of 100, and it can be safe in the flood with a return period of 1000.

No one has ever seen the "once-in-a-thousand-year" flood, and all the data are calculated according to the limited historical materials that people have. 1August, 975, the real flood came. The heavy rain from the sky is staggering: its rainfall is twice as high as the design standard of "once in a thousand years"!