Benefit evaluation of landslide prevention project in Qukou Town, Kaixian County, Chongqing

I. Overview of landslide treatment project in Qukou Town, Kaixian County

Qukou Town, Kaixian County, as the relocation market town of Three Gorges immigrants, is located on the mouth landslide at the intersection of Pengxi River and Puri River. The new site of Qukou Town is located in Xinglong Bridge-Hejiabang-Ju Ping area, with an altitude of 200-295 meters and an area of 0.36 square kilometers. The ports are arranged on the bank slopes on the north and south sides of Shuanghe River. It has a population of more than 4,000 people and a land area of 2 1 .2hm2. Since 1997, resettlement houses and houses have been built, and the completed housing area is about110,000 m2. Roads (including main roads and secondary roads) have been built 650m and 450m, and the construction of electricity, water supply, communication and drainage has reached a considerable scale.

Qukou town ancient landslide is located on the west bank of Pengxi River, starting from Pengxi River in the east, reaching Wangjiayuan in the west, Gangou in the north and Xinglong Qiaogou in the south. The longitudinal length of the landslide is 1700m, the transverse width is 620 ~ 1 100 m, and the plane distribution area is 1. 18km2. The shape of the landslide is tongue-shaped, and the "round chair" terrain at the rear edge is obvious. The leading edge elevation is about 147m, the trailing edge elevation is about 4 10m, the height difference is 263m, and the overall slope is about 10. Baishuwan landslide is a secondary landslide formed on the basis of Qukou ancient landslide, with clear boundary, about 395 meters long and 428 meters wide, with an area of169,000 square meters and a volume of 3.04 million cubic meters. The whole landslide is in a wide tongue shape, with the elevation of the rear edge of the landslide about 270m and the elevation of the front edge 147 ~ 188. Under good airport conditions, the stability of the landslide will be greatly reduced after the impoundment of the Three Gorges Reservoir, and the whole landslide will be basically stable or unstable.

The landslide treatment project in Qukou Town was included in the Master Plan for the Prevention and Control of Geological Disasters in the Three Gorges Reservoir Area, and was approved by the Chongqing Development Planning Commission. According to the preliminary design scheme approved by Chongqing Municipal Bureau of Land and Housing Management, the landslide is treated as a whole, and the treatment scheme of "anti-slide pile supporting and drainage" is adopted. The construction scale is: the landslide area is 6.5438+690 million m2, and the volume is 3.04 million m3. Main engineering quantity: earthwork excavation 65438+300,000 m3, filling 258m3, bar (block) stone 3637m3, concrete 9795m3 and steel bar 723t t. ..

The approved investment estimate is 1 1.57 million yuan. Among them, the main project cost is 7.87 million yuan (6.82 million yuan for anti-sliding project, 654.38+million yuan for slope protection project, 830,000 yuan for drainage project, 20,000 yuan for other projects and 654.38+million yuan for monitoring project), the temporary project cost is160,000 yuan, and the other projects cost is 3 million yuan (including 540,000 yuan for design and 654.33 million yuan for engineering)

Table 3-4- 1 Preliminary Design Investment Estimation Table of Qukou Town Landslide Treatment Project in Kaixian County Unit: 10,000 yuan.

Second, the basic data of disaster reduction benefit evaluation

The main physical indexes of landslide and affected area include the following aspects:

(1) The second-class highway in Wan Kai has a total length of 1.0km, connecting Kaixian and Wanxian, and is an important export highway in Kaixian. The main road of the market town road is 650 meters and the secondary road is 450 meters.

(2) The population is more than 3,700, and the housing area is about 65,438+10,000 m2. The investment is more than 30 million yuan, and the family property150,000 yuan, including the population on the landslide 1500 people, and the housing area is about 40,000 m2. The main relocation units are the town government, primary and secondary school teaching buildings, radio stations, construction management offices and family planning buildings.

(3) Qukou Port is located on the slope of the north bank of Shuangzhai River. Qukou Port is one of the important passenger and cargo distribution centers in Kaixian County. According to the overall planning of Kaixian County, the construction scale of the port area is: the annual passenger traffic is 654.38+million, and the annual freight volume is 600,000 tons.

(4) The national defense optical cable line crosses the front of the landslide, with a total length of about 1.6km.

(5) The total cultivated land area is about 700 mu, including more than 400 mu of paddy fields; There are many trees and fruit trees, which have great economic value.

In front of the landslide is Pengxi River. When the water level rises to 176.76m, if there is a sudden disaster and a large area of landslide occurs, the river course will be blocked, which will directly threaten the urban area of Xinxian County and the immigrant new market town. If the dam breaks, it will seriously affect the downstream Zhao Jiazhen and other places.

Third, the calculation of disaster reduction benefits.

Calculation of social welfare

Social benefit evaluation mainly evaluates the impact of the implementation of landslide control project on people and ensures people's life safety. Multiply the population in the landslide danger area by the population safety vulnerability value to get the maximum possible number of casualties. In this way, the number of casualties that can be reduced by landslide control projects can be evaluated.

According to the statistics of 400 people who died in the Three Gorges reservoir area due to geological disasters, the total population of the reservoir area is 102758, and the ratio of these two parameters is taken as the population security vulnerability, with the value of 0.004.

The maximum possible death toll is 3700× 0.004 = 15.

(2) Calculation of economic benefits

According to the basic data of investigation, the value of various disaster-bearing bodies can be calculated, and the vulnerability of various disaster-bearing bodies can be obtained by checking the summary table of vulnerability experts' opinions, and then multiplied by the maximum possible loss value of various disaster-bearing bodies.

(1) Housing for urban residents: A 1 = 300 yuan/m2×10000m2 = 30 million yuan, V1= 0.8029c1= 30 million yuan× 0.8029 =

(2) Household articles for urban residents: A2 =150,000 Yuan, V2 = 0.8809c2 =150,000 Yuan× 0.8809 = 65438+A2 =1500 yuan.

(3) Cultivated land: A3 = 2,000 yuan × 700 = 6,543.8+0.40 million yuan, V3 = 0.8993c3 = 654.38+0.40 million yuan × 0.8993 = 6,543.8+0.259 million yuan.

(4) Highway: A4 = 2000 yuan×1000+1000 yuan×100 = 365,438+10,000 yuan, v4 = 0.8257c4 = 365,438+10,000 yuan× 0.8228.

(5) National defense optical cable: A5 = 65438+100000×1.6 =140000, V5 = 0.7015c5 =160000× 0.70/kloc.

The maximum possible total loss of disaster-bearing body: c = c1+C2+C3+C4+C5 = 412314000 yuan.

The capital profit and tax rate of this landslide prevention project: b = (c-d)/d = (4123.14-157)/1kloc-0/57 = 256.

The net economic income of the prevention and control project = 4123.14-1157 = 296140,000 yuan.

Input-output ratio =1157: 4123.5438+04 =1:3.56.

(3) Calculation of environmental benefits

The ecological service value of environmental resources is calculated by 20 years × (the number of protected land resources× the ecological service value of land resources): c = 20× 169000× 1.52 yuan /m2 = 5 137600 yuan.

(d) Comprehensive evaluation of disaster reduction benefits

The landslide treatment project in Qukou Town, Kaixian County has protected the life safety and normal life of10.5 million people on Baishuwan landslide. It can reduce the highest death toll 15, and play a role in calming people's hearts and promoting the stable and healthy development of society. The resettlement of 3,700 immigrants ensured the economic development of the immigrant areas.

The landslide treatment project of Qukou Town in Kaixian County ensured the property safety of the relocated market town, and reduced the possible economic loss caused by geological disasters by 4 1.238+0.44 million yuan. The net economic benefit of project management is 29.66.1.4000 yuan; The capital profit and tax rate is 256.4%; The input-output ratio is 1: 3.56, and the economic benefit is remarkable.

The environmental benefits after the implementation of the landslide control project: First, the land resources of 169000m2 on the landslide body are protected from being destroyed, which is equivalent to increasing the ecological service value of land resources by 5 137600 yuan; The second is to reduce the siltation caused by the landslide of 3.04 million m3 soil erosion in the Three Gorges reservoir area, and ensure the effective storage capacity, flood control capacity and service life of the reservoir.