📋 Tender Overview
Floods of 5,000 years occur once is the frequency of floods (or the possibility of floods), rather than reflecting the specific, fixed time with floods. The evaluation of 100 years of floods, 5,000 years is calculating the characteristic of rain, water level, flow in dike design, reservoir, natural disaster prevention planning, not to forecast the specific time of floods. Floods of 5,000 years is a way of interpolation according to statistics based on the series of rain and floods for many years - AnhTheooo NOTICE NOTICE 604/TB -UBND dated July 22 of Nghe An Province informed about the water flow of the Luu Lu Lake of Ban Lu Hydroelectric Lake reaching 9,543 m3/s, close to the flood peak test of 10,500 m3/s (frequency ~ 0.02%, which is 5,000 years occurring). Prior to this information, the public asked the question of whether 5,000 years had a similar flood? Director of the Center for Hydrology and Hai Van, Institute of Hydrometeorology and Climate Change (Ministry of Agriculture and Environment) Luong Huu Dung discussed with the press to clarify this issue. With a 5,000 -year repetitive flood, not 5,000 years to occur once. This is referring to the possibility of occurring, not in time because the floods occur highly random, so it can occur at any time. With a 5,000 -year repetitive cycle corresponding to the probability of 0.02%, it means that the possibility of a larger flood or by this flood is very rare. More specific analysis, Mr. Luong Huu Dung said that if a flood has a repetitive cycle of 5,000 years, which means that the probability of it happens is 1/5,000, or 0.02%. This is a probability value (or possibility), not time attached in terms of concept, in hydrological, flood frequency (symbol P) is understood as the probability of excess. This means that the probability that the flood has a flood flow is greater than or equal to the flow of this probability. Because this is a statistical probability, not a hard cycle. A flood with a probability of 0.02% does not mean to wait for 5,000 years to repeat. In theory, next year it can still occur, but the probability is very low. Director of the Center for Hydrology and Hai Van, Institute of Hydrometeorology and Climate Change (Ministry of Agriculture and Environment) Luong Huu Dung should understand that 5,000 years of floods is a way of experts interpolated according to statistics based on the chain of rain and floods that have been observed for many years. It is like the way of saying historical floods, but here is a clear calculation of probability. For example, the 2 -year flood has once equivalent to 50% occurring each year. Floods for 5,000 years corresponding to the probability of only 0.02% per year, extremely rare but not impossible. Before the question in the case of August, if there is a rain similar to July, whether there is a notice as a 5,000 -year flood? Repeat 5,000 years. It should be noted that the smaller the frequency, the larger the rarity and extreme of the phenomenon, but it does not mean that it does not happen, it is important that the media and specialized agencies must make it clear that this is the frequency of floods (or the possibility of floods), not reflecting the specific time, fixed floods that occur. Article, reservoir, natural disaster prevention planning, not to forecast the specific time of floods. Misunderstanding of this can lead to subjective psychology or bewilderment. Thu CucTham more examinations for further examination
