Guangzhou is located at the junction of land and sea, suffering from land and sea attack and frequent natural disasters. In order to do a good job in disaster prevention and mitigation, Guangzhou Economic Research Institute took the lead in organizing Guangdong Meteorological Bureau, Guangzhou Flood Control and Drought Relief Headquarters Office, Guangzhou Municipal People's Government Earthquake Office and other units to form a "disaster economy" research group of Guangzhou Economic Research Institute to carry out "countermeasures research on the impact of natural disasters on Guangzhou's economic development in the next decade". The author is fortunate to participate in the research work of this topic, and this paper briefly introduces the research situation.
A historical review of major natural disasters
Guangzhou is a natural disaster-prone area. Historically, there have been floods, torrential rains caused by strong convective weather, tropical cyclones, tornadoes, hail and other disastrous weather, droughts, earthquakes, epidemics and other natural disasters. According to historical records, from 1899 to 1949, there were 26 recorded floods, tropical cyclone disasters 1 1 time, 9 droughts and 3 earthquakes of magnitude 4-3/4-5 in Guangzhou. From 1950 to 1999 * *, there were floods 10 times, tropical cyclone disasters 2/kloc-0 times, droughts 4 times, and earthquakes of magnitude 3 or above 23 times (Pearl River Delta region of Guangzhou). In the past hundred years, natural disasters of different degrees have occurred in Guangzhou almost every year, and there is an increasing trend. Looking at the types of natural disasters in Guangzhou, the flood disaster occupies the most prominent position. In recent 50 years, the direct economic loss caused by natural disasters in Guangzhou is about 4.5 billion yuan, and the average annual disaster loss accounts for about 0.3% of the city's GDP, of which the flood loss accounts for about 52. 1% of the total disaster loss. Tropical cyclone disasters are also quite prominent. In addition to its direct losses, tropical cyclone disasters are also manifested as floods caused by heavy rains and storm surges, accounting for 37.438+0% of the total disaster losses. As for drought, it is not serious in the whole country, but the frequency is not low, and it is rarely synchronized with the north. Serious natural disasters have become a restrictive factor for Guangzhou's sustainable development.
Second, the analysis of the current situation of disaster prevention projects in Guangzhou
Over the past 50 years, the people of Guangzhou have made brilliant achievements in self-reliance, large-scale water conservancy construction, comprehensive control of floods, droughts, waterlogging and salt tides, organization of earthquake-proof and earthquake-resistant activities, and construction of disaster prevention and mitigation projects and non-engineering (measures) construction. At present, a basic and reasonable overall layout of disaster prevention and mitigation has been formed, including: a flood control system that focuses on prevention, simultaneously stores and discharges, and combines dikes and reservoirs; Preliminary anti-tropical cyclone system based on rivers and seawalls: drought-resistant system combining water storage, water diversion, electromechanical irrigation and drainage and artificial rainfall; A preliminary anti-seismic system with emphasis on prevention and stress on resistance. However, there are still many weak links, such as: the task of strengthening water conservancy projects is heavy, and the problem of flooding streets in urban areas has not been completely solved; The awareness of typhoon prevention is still weak, the standard of existing tropical cyclone prevention facilities is low, and the construction of wave-proof forest and windbreak forest network lags behind; The city will still suffer from drought once every ten years or more; Weak awareness of earthquake prevention and disaster reduction; Non-engineering (measures) such as comprehensive disaster reduction command and management, safety disaster reduction legislation and disaster economic compensation system are lagging behind. Therefore, the disaster prevention and mitigation work in Guangzhou has a long way to go.
Three. Brief introduction of natural disaster prediction methods
As we all know, the medium and long-term prediction of natural disasters is a major problem in the world today. This paper only introduces the experimental analysis and prediction, and the correctness of the results will be tracked for a long time. The following briefly introduces several forecasting methods.
1. time series method
The change of things is influenced by various factors and often shows randomness. In order to grasp the physical essence and changing law of things, the process of analyzing and processing time series data and extracting useful information from it is called time series analysis. In addition to the commonly used forecasting methods such as mean generating function and maximum entropy spectral regression, this paper also introduces two new time series spectral analysis techniques, wavelet analysis and singular spectrum analysis, to comprehensively analyze and predict the flood, drought and tropical cyclone in Guangzhou in the next 10 year.
2. Stochastic-dynamic climate model prediction method
The prediction made by hydromechanics-thermodynamics equation is called numerical prediction or dynamic prediction. At present, the numerical weather forecast has been able to make a satisfactory forecast of the short-term circulation situation. However, the time limit of daily forecast is 2 to 3 weeks, so the problem of long-term weather forecast and climate forecast for more than one month has not only been solved theoretically, but also numerical calculation is difficult to make progress, such as the accumulation of calculation errors. At present, statistical methods are mainly used for long-term prediction at home and abroad, and dynamic numerical methods are only in the experimental stage. After recent theoretical research, considering the long prediction time of ten years, it is decided to use the stochastic-dynamic climate prediction model to predict the monthly precipitation and the trend of tropical gas years in Guangzhou in the future 10.
3. Expert evaluation method
Expert evaluation method is an evaluation and prediction method that changes qualitative into quantitative according to expert experience and personal judgment. It does not rely on one or a few experts, but on many experts or expert groups. Not only rely on experts in this field, but also invite experts in related fields and socio-economic experts to participate in the forecast, and give full play to the collective effect of experts. Relying on the collective of experts, we can not only eliminate the limitations and one-sidedness of a single expert, but also know from the law of large numbers in mathematical statistics that if the predicted values of n experts are independent and identically distributed random variables, as long as n is large enough, the arithmetic mean of their predictions can approach the mathematical expectation.
4. Extrapolation prediction method of commensurability information system.
Commensurability is essentially an order, so it is an information system. On the basis of astronomical research, Professor Weng, a late former academician of China Academy of Sciences, put forward a general expression of scalable information system. It is generally believed that three-element interval commensurability extrapolation, four-element period indexable extrapolation and five-element interval commensurability extrapolation can be carried out by using the existing data. In the process of random testing. We find that the fewer elements there are, the less likely it is to escape information. Therefore, this topic only extrapolates the historical data of three-dimensional interval, and obtains the confidence level of future floods, tropical cyclones, droughts and earthquakes in Guangzhou.
5. heavenly stems and earthly branches cycle prediction method.
Including "annual trunk and branch period prediction", "daily trunk and branch primary prediction" and "daily trunk and branch secondary prediction", which is an empirical formula method for earthquake disaster prediction using 60 approximate periods.
Based on the results of the above 10 forecasting method, the research group looks forward to the future trends of floods, tropical climate, drought and earthquakes in Guangzhou.
Four, the impact of major natural disasters on Guangzhou's national economic development analysis
1. The secondary industry bears the brunt.
Guangzhou industry, especially heavy industry, occupies an important position in China. As one of the important industrial production bases in Chinese mainland, its total industrial output value has long been ranked second among the top ten cities in Chinese mainland (second only to Shanghai). At present, the main hidden dangers of the secondary industry disaster in our city are as follows: First, major industrial zones (Henan Industrial Zone, Yuancun Industrial Zone, Huangpu Industrial Zone and Tianhe High-tech Park) are set up along the banks of the Pearl River. In the event of flood (waterlogging) and storm surge disasters in Guangzhou, the industrial plants and machinery and equipment in the above industrial zones will be seriously damaged; Second, the original value of industrial fixed assets is huge, and the losses caused by shutdown are huge; Third, according to the development plan of the southeast of our city, the southeast will be built into the "Silicon Valley" of Guangdong Province in the near future, with a large number of high-tech enterprises and even the whole province gathered. By then, the disaster risk in the low-lying areas in the southeast of our city will be deeper; Fourth, because the secondary industry involves all sectors of the national economy, the resumption of work and production is slower than that of the tertiary industry, so it is affected by indirect losses for a long time and in a wide range. It is estimated that the loss of the secondary industry accounts for about 60% of the total loss.
2. The disaster damage of the tertiary industry is the second.
Guangzhou's tertiary industry occupies an important position in the national economy. The four old cities, such as Liwan, Yuexiu, Haizhu and Dongshan, are densely populated and prosperous, and are the most densely populated areas of the tertiary industry in Guangzhou. In case of flood, typhoon and earthquake in Guangzhou, the direct economic loss of the tertiary industry will be very serious, accounting for about 35% of the total loss. Because the original value of its fixed assets is far less than that of the secondary industry, it is easy to return to work, so its indirect economic loss is far less than that of the secondary industry.
3. The loss of primary industry is relatively small.
Although the loss of primary industry accounts for a small proportion of disasters, the proportion of disasters in GDP (primary industry) is increasing. The township economy in our city has sprung up suddenly and become a "new force" of the national economy, occupying a certain position in the city's GDP. Once the rural areas in Guangzhou encounter natural disasters, the township economy bears the brunt. Although the disasters and losses since the 1950s have not posed a serious threat to the city's GDP and fiscal revenue, people's lives and property can't be treated as trivial matters, and people's hearts can't be violated!
According to the economic development level of Guangzhou (65,438+0,998), we estimate that the direct economic loss of a major flood in the next decade will reach 65,438+0,654,38+0.6 ~ 654,38+0.72 billion RMB.