Discussion on Causes and Countermeasures of Mountain Flood Disasters in Shaoyang City

Discussion on Causes and Countermeasures of Shaoyang Mountain Flood Disaster

I. Geographical location and flood disaster overview

The city is located in the southwest of Xiangzhong, upstream of Zishui, east to Hengyang, south to Yongzhou and Guangxi Guilin, west to Huaihua, north to Loudi, and the city has eight counties, one city and three districts, with a total population of 7.3 million. Among them, the agricultural population is 6.11 million, and the total land area is 20,875 square kilometers, of which 4.9 million mu is cultivated land, which is a typical agricultural market.

The city is the transitional zone between the Jiangnan hills and the Yunnan-Guizhou plateau. The western Xuefeng Mountains are the eastern regions of the Yunnan-Guizhou Plateau, and the eastern and central regions are the western regions of the Hengshao Hill Basin. The city is surrounded by mountains in the north, west and south, and the hills in the middle and east are undulating. The plains are inlaid among them, showing a basin topography inclined from the southwest to the northeast. The terrain ratio is reduced to 10.25%. The Zijiang River has two sources, the tributaries are vertical and horizontal, and the “Y” shape flows from the southwest to the northeast. The drainage area covers the 8 counties, 1 city and 3 districts under the jurisdiction of the city.

The city is a region with frequent floods and disasters. According to statistics, in the past 300 years, there have been 73 floods, an average of 4.1 years, and in the 52 years after the founding of the country, there were 17 years of floods. Due to the rapid outbreak of floods in the hilly areas, it has been short-lived, but it has often brought devastating blows to the national economy and people's lives and property. In the "6.27" flood in 1979, 87 people were killed and 550 people were injured. Among them, 56 people died in Dongkou County and 466 people were injured. In 1988, 41 people died in floods. The 1996 floods were characterized by overall and devastating effects. The water level of the main stream of Shaoyang City is 222.21 meters, which is 8.21 meters above the warning level. All the 8 districts, 1 city and 3 districts of the city have been affected. 196 towns and villages have been affected by different degrees of disasters, including 71 townships, accounting for 36.2 of the total. %. Of the 7.04 million people, 5,160,500 were affected, accounting for 73.3% of the total, 688,300 were trapped by floods, 422,300 were transferred urgently, and 82 were killed in the flood. There were 137,700 houses collapsed and 2.513 million square meters, and 2,267,100 mu of crops were damaged. The direct economic loss was 7.5 billion yuan, of which the direct economic loss of water conservancy facilities was 873 million yuan. The place where the flood passed, leaving behind a ruin, the people said: "Working hard for decades, return to liberation." This year, due to the concentrated rainstorms of “5.26” and “6.21”, there were 63 counties and cities in Suining, Xinning, Shaodong and Wugang, and 63 towns affected by the disaster. The affected population was 775,000. The direct economic loss of the city was 1.9986 billion yuan. . Among them, the affected area of ​​crops was 32.88 thousand hectares, the area of ​​disasters was 10.18 thousand hectares, and the harvest was 0.51 thousand hectares, and the grain production was reduced by 17,400 tons. The storm floods also caused great damage to the city's water conservancy facilities, damaged 6 reservoirs, damaged the embankment 1450 at 89 km, destroyed 199 pond dams, and directly lost 38.5 million yuan in water conservancy facilities.

Second, the cause analysis

Analysis of the causes of frequent mountain torrent disasters in our city, mainly in the following aspects:

1. Heavy rain intensity. The intensity of heavy rain is the main reason for inducing flash floods. There are three storm centers in the city basin: one is the basin above the mouth, the other is near the Liudu Village, and the third is the Guangxi resources. Due to the existence of three storm centers in the basin, coupled with special terrain conditions, the slope is large, resulting in a very short confluence time, unexpected floods, sudden bursts, and fierce, high peaks. Local floods caused by local heavy rains and widespread floods. When it is a full-rainstorm, the irregular movement of the rainstorm center often causes a complex combination of floods. In the flood that affects urban flood control, the proportion of incoming water in the muddy water is large, accounting for about 70%, and about 30% of the water. %, the inflow of Shaoshui often changes the flood control situation in the urban area. Taking the mountain torrents in 1996 as evidence, in the 6 hours from 14:00 to 20:00 on July 10, the three stations of Gaosha, Huangqiao and Dongkou had 124 mm, 105 mm and 70 mm respectively, of which 3 hours were respectively. Rainfall 80mm, 70mm and 50mm, from 8:00 on the 16th to 8:00 on the 17th, the city's heavy rains reached its peak. The heavy rains over 100mm have 5 stations including Dangping, Wuyang, Shanmen, Dongkou and Xiaoshajiang. The Dangping Station reaches 146 mm and the maximum rainfall is 78 mm. The Shangshajiang Reservoir Area of ​​Shaodong County was 3:40 am to 4:50 am on the 18th, with a rainfall of 90.4 mm in 70 minutes. Not only the torrential rains in the city, but also the intensity of the rainstorm in the passenger water basin is very alarming. The Guangxi County has a rainfall of 400 mm from 20:00 on the 15th to 2 am on the 18th, which has aggravated the steep rise of the city. Under the violent rainstorm, the water level of the rivers in the city has soared. The Pingxi River, Lishui, Fuyishui, Shaoshui and Zishui, which are known as the Dajiang River in the city, have the highest water level in history.

2. The ecological environment has deteriorated. The destruction of the ecological environment has intensified the formation of mountain torrents. Our city is a typical hilly mountainous area. The forest coverage rate in the past has been relatively high. From the end of the 1950s, it has experienced many such things as “Dazhi Iron and Steel”, “Daxing Public Canteen”, “Agricultural Dazhai” and “Cultural Revolution”. The people's movement with the word "big" has been over-expanded and deforested. Many lush green hills have become "scorpion heads" and "monk heads". The vegetation has been seriously damaged. The area of ​​forest land and forest coverage have decreased compared with 1957. About 20%, a few places reduced by six or seven. At the same time, more than 1 million mu of forests in the city have been reduced to cultivated land, causing severe damage to the “green reservoir”. The area of ​​soil erosion has increased by 43% compared with 1957. The deterioration of the ecological environment is not only harmful to the regulation of microclimate, but also greatly reduces the ability to conserve water, causing mountain flood disasters, and causing a large amount of mud and sand, forming earth and rock flows, flooding into rivers and water conservancy projects, silting waters, and weakening flood control capacity. The city's existing soil erosion area is 4,200 square kilometers, and the water erosion modulus reaches 4,000 tons / square kilometers. According to this calculation, more than 10 million tons of mud sand is injected into rivers, ditches and shoals every year. It is generally reflected that riverbeds are generally more than 1 meter higher than in the mid-fifties. Chenhe River in Longhui County, Shima River in Xinshao County, Xinzhai River in Xinning County, Sanshuang River in Suining County, etc. "hanging river".

3. Low engineering standards and poor flood storage capacity. Since the founding of the People's Republic of China, the city has carried out large-scale and fruitful water conservancy construction, and has built a large number of water conservancy projects. However, due to insufficient water conservancy investment, the construction of the local law is not high, especially after the long-term operation of the reservoir, the aging is serious. According to the statistics of this year's flood season, there are still 328 diseases in the 1,246 reservoirs in the city, accounting for 26.3%. These reservoirs are fearful and can only control the water level operation during the flood season, and it is difficult to play the peak of flood discharge. effect. In addition, in the upper reaches of Zishui, except for the Liuduzhai large reservoir built on the Minshui water system, there are no backbone water conservancy projects, and the Fuyi water system has few medium-sized reservoirs, and the ability to intercept floods is weaker.

4. There are many obstacles in the river, and the flood discharge is not smooth. Some people are not aware of the floods, lack of a general concept, and violate the rules and regulations. Sand mining in the river, gold dumping, blocking the river; dumping waste and garbage into the river; building warehouses, docks, houses, etc. on the river beach, randomly invading the flood section, causing the riverbed to rise continuously and the river surface changing Narrow, severely hindered the normal discharge of the flood. For example, the slope of the Zijiang River section has dropped from 0.039% in 1956 to 0.027% in 1996, and the Xinzhai River in the lower reaches of the Dazhen Reservoir has been safely drained from 637 cubic meters per second. Reduced to 120 cubic meters / sec, beyond this limit will flood the house.

5. Human factors cause local landslides, leading to mountain disasters. Mining ore, road construction and construction on the mountain with poor geological conditions destroys the mountain structure. Under the intensification of heavy rainfall, landslides and earth-rock flows are often accompanied by floods, causing houses to collapse, casualties, power and telecommunications lines. The pole, the traffic road was interrupted, and the farmland was destroyed.

Third, the discussion of disaster reduction measures

It is still not too late to seriously rectify the experience and lessons. In response to the subjective and objective factors of frequent mountain torrents, we must take comprehensive measures to cure the symptoms.

1. Intensify publicity and enhance the awareness of mountain flood disasters. In the prevention of mountain flood disasters, there is a widespread paralysis and luck, and disaster prevention and mitigation is regarded as “short-term behavior” and “passive behavior”. Disasters often occur, and are often caught off guard. Beaten. Disaster prevention and disaster prevention involves all aspects of the whole society and involves all sectors of all walks of life. Therefore, we must mobilize the strength of the whole society and invest in the fight against disasters and disasters with a positive attitude, and establish a comprehensive disaster prevention and protection, disaster relief and harvest, and disaster relief. The idea of ​​development should be to strengthen the awareness of disaster prevention and mitigation as a regular work. First, we must use radio, television, newspapers, reports, and other propaganda media, plan and carry out propaganda and launch work in a targeted manner to enhance the awareness of disaster prevention for the whole people. Second, strengthen education and training, and teach relevant knowledge on disaster prevention and resilience. To enhance the awareness of disaster prevention and resilience; the third is to raise the awareness of citizens to participate in disaster prevention and resilience, and recognize that disaster prevention and resilience is the obligation of every citizen; the fourth is to establish a sound command system and organize a strong rescue team.

2. Establish a special mountain flood disaster prevention responsibility system. All relevant departments and units must clarify their responsibilities and perform their duties and responsibilities. The geology and mineral resources departments shall strengthen the monitoring, forecasting and forecasting of mountain flood disasters, especially the geology and mining departments shall strengthen investigation and research and formulate specific management plans; the construction and land departments shall take measures to stop construction and development in the Shanhong Yifa area. . In the "5.26" flood disaster this year, due to the accurate and timely forecast by the meteorological department, the flood control responsibilities of all levels and departments were implemented, and various preparations were made in advance, and the initiative was seized in the disaster against mountain floods. Although it was attacked by torrential rains, there was no Causing death.

3. Make great efforts to build water conservancy infrastructure. Doing a good job in water conservancy infrastructure and improving resilience is a powerful guarantee for disaster prevention and mitigation. In order to meet the needs of mountain torrent disasters, the project construction should focus on three aspects: First, grasp the reinforcement of the reservoir. Concentrate energy, financial resources, material resources, fight the dying battle of dangerous reservoirs, and strive to remove the hats of existing dangerous reservoirs within three to five years to ensure full operation and exert its normal flood control benefits. The second is to grasp the construction of urban flood control projects. In the event of a mountain torrent disaster, the most common losses are in urban areas. Therefore, it is necessary to incorporate the construction of urban flood control dykes into the important contents of urban planning and urban construction, and repair the “Bao Ming Dyke” to ensure the safety of towns. The third is to strive for the construction of key flood control projects. According to our plan, if the Wangmutang Reservoir can be built in the upper reaches of Fuyi Water, and the key backbone projects such as Dongkoutang Reservoir and Shanmen Reservoir will be built in the upper reaches of the Lishui River, the mountain flood disasters in Shaoyang will be fundamentally treated.

4. Committed to the implementation of ecological engineering governance. Soil and water conservation is the lifeline of mountain development, a fundamental measure for land remediation and river governance, and the basis for national economic and social development. Water and soil conservation management should adhere to the combination of biological measures and engineering measures, and take the approach of biological measures to do a good job of closing hillsides for afforestation and building soil and water conservation forests, stopping deforestation and deforestation, expanding forest cover and increasing vegetation. It is necessary to increase the investment on the steep slope caused by excavation and carry out slope protection. At present, the city should focus on the ecological management of Changshao County, such as Xinshao, Longhui and Shaodong, to achieve results, capture the experience, and popularize it throughout the city.

5. Control water according to law and increase the governance of river courses. It is necessary to use legal weapons to correct the current situation of multiple water pipes and to implement unified management of rivers. We must conscientiously publicize and implement the "Regulations on River Regulations", promote the experience of comprehensive river management in the city, vigorously crack down on the "four chaos" behavior, do a good job in the obstacle-free work of large and small rivers, remove old obstacles within a time limit, and eliminate new obstacles. Construction projects involving rivers must be submitted to the river authorities for approval in strict accordance with legal procedures. It is necessary to reverse the situation of poor flooding of rivers as soon as possible through the standardized management of water resources and water resources.