Evaluation of Economic Losses Caused by Debris Flow

I. Definition of debris flow and vulnerability

Debris flow is a geological process between flowing water and landslide. Typical debris flow consists of thick mud suspended with coarse solid debris, which is rich in silt and clay. Under appropriate topographic conditions, a large number of water bodies soak the solid accumulation materials in the hillside or gully bed, which reduces its stability, and the solid accumulation materials filled with water move under their own gravity, forming mudslides. Debris flow is a disastrous geological phenomenon. Debris flow often erupts suddenly, with fierce power, can carry huge stones at high speed, and is powerful and destructive. Everything was destroyed wherever the mudslide went.

The definition of vulnerability published by the United Nations in 1992 is "the degree of loss that may be caused by potential damage", and Liu Xilin and others define it as "the potential total loss that may be caused by potential natural disasters in a given area and period".

Second, the economic loss evaluation index system of Luoyugou debris flow [102, 103]

Debris flow has caused many economic losses, such as building assets, indoor property, land value, population, industrial and agricultural production, underground pipelines, transmission lines, transportation and so on. The key is how to choose the factors that can not only represent the main content of the loss, but also reflect the regional characteristics, and make them easy to quantify, so as to achieve the scientific, reasonable and operational purpose.

In the specific calculation, economic losses are calculated in three categories:

1. Social and economic loss index of personnel

Personnel loss mainly refers to the death loss and injury loss caused by disasters and their indirect losses (such as mental loss or psychological injury), which are influenced by social structure (scale, density, age, education and wealth). According to the International Union of Geological Sciences (IU2GS), human vulnerability is expressed as the probability that natural disasters will affect the life of a certain group of people. Because the debris flow in Luoyugou has a large influence range, it can be evaluated and calculated according to the area (region).

Therefore, we consider using indirect methods to quantify social and economic losses. The greatest possible loss of life is related to population density. The greater the population density in a region, the greater the possibility of people's life loss in the event of natural disasters, that is, the greater the economic loss; It is also related to the quality of the population. Older people over 65 and children under 15 are more vulnerable than people of other age groups. Vulnerability is also related to education level. People with good education are less vulnerable, while those with less education are more vulnerable. In addition, wealth also affects vulnerability. The rural population is relatively poor, and they are more vulnerable than urban residents.

The evaluation model of social and economic loss index of regional debris flow personnel is as follows:

Economic evaluation of urban geological environment risk

Among them, V 1 is the economic loss of geological disaster personnel, ten thousand yuan; γ is the average economic loss of death, 10,000 yuan/person-year; P is population, people; α is the ratio of indirect loss to direct loss,%; D is population density, person/km2; S is the affected area, km2.

2. Material economic loss index

The index of material economic loss includes tangible assets and intangible assets, and tangible assets can be represented by fixed assets.

Intangible assets can use gross domestic product (GDP) as a comprehensive indicator representing economic losses. Obviously, the greater the GDP of a region, the greater the economic loss when the region suffers from natural disasters.

The evaluation model of regional debris flow material economic loss index is as follows:

Economic evaluation of urban geological environment risk

Where V2 is the economic loss of geological disaster property, ten thousand yuan; V2 1 Economic loss of tangible assets caused by geological disasters, ten thousand yuan; V22 is the economic loss of intangible assets caused by geological disasters, 10,000 yuan; Y 1 is building damage, ten thousand yuan; Y2 is the loss of assets, ten thousand yuan; Y3 is the flow loss, ten thousand yuan; Y4 is pipeline loss, RMB 10,000.

3. Indicators of resource, environment and economic losses

Environmental economic losses, that is, economic losses of natural resources, mainly include losses of water, gas and land resources. Forest resources are taken into account in economic losses. For debris flow, land resources are the main source of environmental vulnerability and can be used as the main index to represent environmental and economic losses. Obviously, the greater the value of land resources, the greater the land loss when suffering from mudslides, that is, the greater the economic loss. Land value depends not only on land quality and land use mode, but also on market conditions, which change rapidly and are difficult to predict. Therefore, it is difficult to directly evaluate the land value. For simplicity, reference is made to different land types to artificially give the benchmark price, so as to calculate the regional economic losses. Considering that land only reflects its value and price when it is used and traded, the life of land use right in China is usually 70 years at present, so this index usually takes the annual average.

Economic evaluation of urban geological environment risk

Where V3 is the economic loss of geological disaster resources and environment, 10,000 yuan; T refers to the economic loss of land resources caused by geological disasters, ten thousand yuan; Ai is the unit value of land, ten thousand yuan/km2; Pi refers to the economic loss of intangible assets caused by geological disasters, ten thousand yuan; I is the land use type, each; In addition, economic losses include direct economic losses and indirect economic losses.

The direct economic loss of disasters refers to the sum of economic losses caused by the same disaster, including primary disasters and closely related secondary disasters. For example, when buildings, industrial and mining structures collapse and rural roads are destroyed, it may also cause water, gas, electricity, fire and traffic jams, and the losses caused by it can be counted as direct losses of disasters. This is because in such a disaster assessment, it is impossible to distinguish between primary disasters and secondary disasters in a short time.

When a disaster process basically ends, the losses caused by the pause, slowdown and imbalance of industrial and mining process, trade finance, social welfare and management caused by this disaster can be regarded as indirect economic losses, so it is generally equivalent to derivative disasters.

Third, the economic loss assessment of Luoyugou debris flow

Luoyugou is located in the north of Qincheng District, with east longitude105 30'-105 45' and north latitude 34 34'-34 40'. As a first-class tributary of Weihe River, the total basin area is 7 1.37km2, involving Qin Cheng.

The terrain in the basin is different, the slope is steep, the vegetation is scarce, there are many local rainstorms, the duration is short, the intensity is high, and the confluence is fast. Rainstorms often cause mountain torrents, mudslides and other mountain torrents, accompanied by landslides. It poses a great threat to the lives and property of the people in Tianshui city in the lower reaches.

1. Social and economic losses of personnel

The debris flow disaster in Luoyugou involves Qincheng District and Beidao District, with a population of 1 1.3442 million, including 86,000 urban residents and 27,442 rural residents. See table 6-4- 1 for the basic population profile.

Table 6-4- 1 Population Statistics of Luoyugou Basin Affected Area

Personnel losses include direct losses and indirect losses, and direct losses mainly include death losses and injury losses due to disasters. The former refers to the loss caused by the death of people caused by landslides; The latter refers to injuries, diseases and medical losses caused by landslides. Indirect loss mainly refers to the mental loss or psychological injury of personnel.

The economic losses of regional debris flow personnel are as follows

V 1=30 years ×0.4 (ten thousand yuan/person-year) ×2.7442 (ten thousand person-year) +30 (year) × 1 (ten thousand yuan/person-year) ×8.6 (ten thousand yuan) (1+3.5) =

In general disaster research, only the direct loss of personnel is generally analyzed, but the indirect loss is not considered. In calculation, a correction coefficient α is added on the basis of direct loss. In order to ensure the accuracy of calculation, a correction coefficient of 3.5 is adopted.

2. Material and economic losses

Tangible assets can be represented by fixed assets, including the following six categories.

2. 1 building loss

Building losses mainly include damaged, destroyed and buried houses, shops, houses, office buildings and other buildings. Including urban residential buildings, rural residential buildings, hotels, restaurants, apartments, commercial buildings, schools, hospitals, institutions, military barracks, industrial workshops, warehouses, stations, docks, etc. See Table 6-4-2 for the calculation standards.

Table 6-4-2 Building Unit Price (Refer to Building Standards)

The threatened area of debris flow is 8.5km2. According to the overall building proportion, the building area is about 37%, and the area is about 8.5km2×37%=3. 145km2. According to the average building loss, 600 yuan /m2, x4 = 3145,000m2× 600 yuan/m2 =18.87 million.

2.2 Loss of assets

Asset losses mainly refer to agricultural products losses, livestock losses, indoor and outdoor property losses, industrial losses and other losses caused by mudslides.

2.2. 1 loss of agricultural products

The loss of agricultural products can be estimated by market value method. The gross domestic product of the threatened area is 4095 1.59 million mu, and the output of main agricultural products is 4226t of grain and 243.5t of oil. The gross domestic product of the control area is 277.38 million mu, and the output of main agricultural products is 1827t, and the oil is 94 t.

Sn=2.5 (yuan/kg) × (4226+1827) (t )×1000+4 (yuan/kg )× (243.5+94 )×1000 =/kloc-.

2.2.2 Loss of livestock

The market price of livestock varies from place to place. For the convenience of unified measurement, the average price of large livestock is 1300 yuan/head and that of small livestock is 30 yuan/head. Each item is valued according to its specific loss quantity. There are 2429 large livestock and 568 small livestock/kloc-0 in the threatened area; There are 856 large livestock and 523 small livestock in the prevention and control area.

SL =1300× (2429+856)+30× (1568+523) = 4,323,200 yuan.

2.2.3 indoor and outdoor property losses

Generally, the number of damaged and damaged houses is investigated first, and then the specific losses are calculated. Due to different regions, indoor property losses vary greatly. The loss of indoor property is calculated according to the average loss of personnel. Based on per capita 1000 yuan, Sc= 1000 yuan/person ×165438+34.42 million people =1/34.42 million yuan.

2.2.4 Industrial losses

Industrial losses mainly refer to the loss of fixed assets of these factories, amounting to 74130,000 yuan.

Table 6-4-3 Survey Statistics of Major Industrial and Mining Enterprises in Luoyugou Debris Flow Affected Area

Table 6-4-4 Statistics of Asset Loss

2.3 Traffic losses

Debris flow often has a serious impact on local traffic, and traffic loss is an important aspect of economic loss. Traffic losses mainly include the loss of important traffic facilities such as roads, railways and bridges. Expressed as

Economic evaluation of urban geological environment risk

Type (6-4-6), Sg for highway loss, ten thousand yuan; St is the railway loss, 10,000 yuan; Sq refers to bridge damage, RMB 10,000 Yuan.

Highway loss is the product of the length of highway damaged by debris flow and its corresponding unit engineering cost. After consultation with relevant departments, the cost of highway basic engineering is shown in Table 6-4-2. Due to the different geological and geomorphological conditions, even the same grade of highway, the project cost varies greatly, depending on its specific conditions. After consulting relevant departments, the cost of highway basic engineering is shown in the following table 6-4-5. See table 6-4-6 for the cost of railway basic engineering. Its calculation method is the same as highway loss. Bridges are divided into pedestrian bridges, highway bridges and railway bridges according to their uses, and the building materials used are also different. Therefore, when calculating the bridge loss, it should be analyzed according to the actual situation in the disaster area.

Table 6-4-5 Unit Project Cost of Grade Highway

sequential

Table 6-4-6 Railway Engineering Costs under Different Terrains

There are 4 transit highways, including 2 in Qincheng District and 2 in Luoyugou, all of which are national highways. Length * * * 6km, total fixed assets1.200 million yuan; According to statistics, if there is no transit railway, it will not count; There are 8 secondary bridges with a total length of 0.4km, and the total fixed assets are 24 million yuan, calculated at 6 million yuan each.

Table 6-4-7 Statistics of Traffic Loss in Luoyugou Affected Area

2.4 pipeline loss

Pipeline loss (y4) refers to the loss cost of communication, power supply, water supply, gas supply and other important pipelines damaged in the disaster, and the unit is 10,000 yuan. Pipeline loss is often regarded as lifeline engineering loss. Different pipelines have different engineering costs per kilometer. In order to facilitate the calculation, referring to the market price, the cost of high-voltage transmission lines is 200,000 yuan/km, and the communication facilities are calculated at 220,000 yuan/km, and then multiplied by the damaged pipeline length to obtain the required pipeline loss.

Table 6-4-8 Statistical Table of Pipeline Loss in the Affected Area of Luoyugou

2.5 Other losses

There are 3 water conservancy facilities, and the data shows that the fixed assets are 929,000 yuan; 3. Tap water, fixed assets of 2 million yuan; Park 1 unit, fixed assets100000 yuan; There are two squares with fixed assets of 2 million yuan.

Table 6-4-9 Statistics of Other Material Losses in Luoyugou Disaster Area

2.6 Loss of intangible assets

Intangible assets can use gross domestic product (GDP) as an indicator of economic losses. See table 6-4- 10 for the specific calculation results:

Table 6-4- 10 Statistics of Intangible Assets Loss in Luoyugou Disaster Area

Table 6-4- 1 1 Statistics of Intangible Assets Loss in Luoyugou Disaster Area

3. Resources, environment and economic losses

In the evaluation of debris flow disaster loss, the resource loss we consider mainly refers to the land resources affected or destroyed by debris flow disaster. In the process of quantifying land resources, it is very important to judge whether the land has suffered permanent damage. Through certain measures after the disaster, most land resources can be partially or even completely restored. Therefore, when evaluating the loss of resources, we only need to consider the cost of cleaning and restoration, and the specific calculation is based on 1% of the damaged area and the benchmark price of this land type. See table 6-4- 12 for the benchmark price of land resources. In the actual evaluation, the benchmark price of land resources can be appropriately adjusted according to local conditions.

Table 6-4- 12 Estimation of benchmark price of land resources in China

The total affected area is 60.47 square kilometers, and the cultivated land area is 53,000 mu.

The value of land resources is

X9=300 yuan/m2× 60.47×106m2 =18141ten thousand yuan.

X9=200 yuan/m2× 5.3x106m2 = 70.596 million yuan.

The total amount is1814100+7059.6 =1821596000 yuan.

Table 6-4- 13 Summary of Economic Losses

Once the once-in-50-year flood occurs in Luoyugou, Tianshui City, Gansu Province, a huge debris flow will occur, and the total economic loss will reach 2 1.2 billion yuan, which is huge.