How to predict the scale of the flood and how to calculate the economic loss account
Experts from the Academy of Water Sciences Analyze Hot Issues in Flood Control
The water level in the middle and lower reaches of the Yangtze River and the two lakes has been over-alarm for nearly half a month. The dikes have been soaked in high water levels for a long time, and the risks have increased. The weather forecast shows that from July 21-23, there will still be heavy rainfall in many places along the river. Regarding the hot issues of flood prevention of public concern, a reporter from China Youth Daily and China Youth Daily interviewed Li Na, director of the Flood Management and Impact Assessment Research Department of the Disaster Reduction Center of the China Institute of Water Resources and Hydropower Research.
After years of construction, my country has built 312,000 kilometers of dikes above level 5, 98,000 reservoirs, 104,000 sluices, and 98 national-level flood storage and detention areas. The flood resistance has been greatly improved. Why does the economic loss caused by the flood seem to be greater?
In this regard, Li Na believes that this is due to the increase in total assets per unit area and the concentration of assets in flood control areas. From 1952 to 2018, my country’s GDP increased by 174 times, which is reflected in direct economic losses, which is reflected in an increase in the absolute value of losses, but the proportion of economic losses caused by floods in the total economy has often decreased.
The loss of flood disaster generally includes economic loss and non-economic loss (such as loss of life and health, loss of ecological environment, etc.). According to statistics from the Ministry of National Defense and Water Resources, in the past 70 years, the annual number of deaths caused by floods has decreased from about 8,000 in the 1950s to about 800 in the past 10 years; direct economic losses accounted for the proportion of GDP that year The average value decreased from 2.39% before 2000 to 0.4% from 2010 to 2018.
She believes that relying on rapid economic development, the growth rate of household and personal income is significantly higher than the growth rate of flood losses; the national disaster relief efforts continue to increase, and the public's ability to withstand disasters economically has objectively increased with the times. With the construction of flood control projects and the improvement of flood control standards, the possibility of disaster-causing floods is reduced. However, in a long-term stable life, floods happen unexpectedly, and people's psychological endurance may be more vulnerable.
Recently, in response to dangerous situations, flood storage areas have been opened for flood diversion, and more than 2,000 people have been transferred from Mengwa in Anhui Province. In the face of disasters, the people's house in the flood storage area is for everyone, which is moving. Many people are concerned about whether flood control can reduce the pressure of flood control in the middle and lower reaches and reduce losses?
Li Na introduced that the flood prevention reservoir has the function of blocking floods and reducing downstream flood peaks. If upstream water is not blocked, greater flood peak discharge and higher water levels will be formed in downstream areas, and people in downstream areas will face higher Risk and bear more serious losses. Under normal circumstances, when the water conservancy department conducts flood control projects in the basin, it will consider the flood control projects, upstream and downstream, and left and right banks in the basin as a whole. On the premise of ensuring the safety of water conservancy facilities, consider the overall flood control benefits of the river basin, minimize the impact of floods, and improve the overall flood control capacity and comprehensive benefits of the river basin.
Li Na specially introduced that at present, my country's water control thinking has changed from flood control to flood management. Since 2013, the Ministry of Water Resources has gradually carried out a basic work, compiling a flood risk map of about 500,000 square kilometers in key areas across the country, providing basis and support for advancing risk management.
What role do small and medium rivers play in my flood defense work? What are the shortcomings to make up?
"my country has a large number of small and medium-sized rivers. There are more than 9,900 small and medium-sized rivers with a basin area of 200-3000 square kilometers, and the number below 200 square kilometers is also very large." Li Na pointed out that they have three main problems:
First, the behavior of blindly occupying the management scope of the river course has been repeatedly prohibited, and a large number of assets have entered the flood risk area of small and medium-sized rivers, resulting in a rapid increase in flood losses; second, the lack of overall planning and comprehensive management that takes into account the overall flood control and ecological protection, and improvement has caused some places There has even been a phenomenon called remediation, which is actually used for beach reclamation; third, many river-crossing, river-crossing, and river-side construction projects have not carried out flood impact assessments in accordance with the provisions of the flood control law, not only invading the water itself, but also becoming water blocking obstacles. Reduce the flood carrying capacity of the river, raise the flood level, and increase the flood risk of others. In addition, many small and medium-sized rivers in many places do not have special management and protection institutions and management funds, and some areas have not yet formed an effective and feasible long-term operation management and protection mechanism for small and medium-sized rivers, and have not strictly implemented the main body of responsibility, management and protection methods, and management after construction. The problems of funding, mess and poorness are still prominent.
Li Na suggested that, in accordance with the provisions of the Flood Control Law, comprehensively delimit the management scope of small and medium rivers, strictly prohibit occupation, maintain the flood discharge capacity and ecological environment functions of the river; carry out flood impact assessments on construction projects in areas where floods may inundate and promote reasonable progress Orderly construction; comprehensive planning and governance based on the basin as a unit; division of powers, implementation of supervision responsibilities, and innovative maintenance and management mechanisms for flood control projects.
Our newspaper, Beijing, July 22nd
China Youth Daily·China Youth Daily reporter Li Chenhe Source: China Youth Daily