Reservoir irrigation engineering design?

This paper introduces the basic water conservancy calculation, engineering design and economic benefit of Magou Reservoir. The construction of this project can solve the problems of drinking water for people and livestock and agricultural irrigation in irrigation area, which can be used for reference.

1 engineering background

At present, reservoir irrigation is an effective water supply irrigation measure [1-5]. The irrigation project of Magou Reservoir is located in Magou Village, Sidu Town, Huichuan District, Zunyi City. It is the only high water source point in the northern part of Zunyi City. The dam site is about 8.0km away from 2 10 national highway in Sidu town and 37.0km away from Zunyi city. Rural roads pass through the dam site, and the project has convenient external transportation. The basin area above the dam site of Magou Reservoir is 57.0km2 (including open flow 14.2km2, undercurrent and depression 42.8km2), the length of main channel 16.2km, and the average gradient of main channel is 26.2‰.

The annual average flow of the dam site is 1.09 m3/s, and the annual average runoff is 34.4 million m3. The design river basin and irrigation area belong to the humid climate of mid-subtropical monsoon, with no severe cold in winter and no heat in summer. Due to the influence of the warm and humid air currents in the southeast ocean and the Bay of Bengal, the rainfall is sufficient, the frost-free period is long, and the light, heat and water are in the same season, which is beneficial to crop growth. The main task of irrigation project in Magou Reservoir is irrigation. After the completion of the project, it will solve the irrigation problems of 3924.5 hm2(58868 mu) farmland and the drinking water problems of10.5 million people, 3,000 large livestock and10.2 million small livestock.

2 the necessity of engineering construction

There are only two small reservoirs in the irrigation area of Magou Reservoir: Shuangxian Reservoir and Dachanggou Reservoir: (1) Dachanggou Reservoir's total storage capacity 1.4 million m3, Li Xing storage capacity 1.4 million m3, the outlet elevation of drainage culvert is 932.8m, the designed irrigation area is 3,668mu, and the irrigation water surface elevation is 930.0m (2) The total storage capacity of Shuangxian Reservoir after danger removal is 65,433. The outlet elevation of drainage culvert is 963. 1m, the designed irrigation area is 5 100 mu, and the irrigation water surface elevation is below 960.00m; The designed irrigation area of the two reservoirs is 8768 mu, and now they are responsible for irrigation and drinking water storage in Sidu Town. However, due to the long-term siltation operation of two small reservoirs, Shuangxian and Dachanggou, which have been built for many years, the water intake guarantee rate of the reservoirs is low. In addition, the elevation of the reservoir itself is low, and the area it can cover is also small. Due to the lack of water resources, water can not be guaranteed, which hinders the development of green industry and grain output. In order to better benefit the local people and promote the healthy development of rural economy, we must solve the problem of water shortage as soon as possible. The irrigation infrastructure in the project area is weak, the degree of irrigation is low, and the problem of irrigation water is outstanding. It is urgent to build large-scale water conservancy projects to solve the current situation of drought and water shortage in the project area.

3 engineering water conservancy calculation

The main task of irrigation project in Magou Reservoir is irrigation. After the completion of the project, it will solve the irrigation problems of 3924.5 hm2(58868 mu) farmland and the drinking water problems of10.5 million people, 3,000 large livestock and10.2 million small livestock. Considering the socio-economic development, local water resources conditions and the characteristics of water supply objects, the guarantee rate of irrigation, rural drinking water supply and environmental water supply is P=80%, p = 95% and P=90%, respectively.

3. 1 Determination of normal water level

According to the actual situation of this project, considering the dam construction conditions, project investment, reservoir water volume calculation and other factors, in order to meet the requirements of river planning, three normal water storage level schemes, 1036m, 1038m and 1040m, were preliminarily drawn up in the feasibility study stage of this project for comparison. From the calculation of water quantity, when the normal water level of Magou Reservoir is raised from 1.036m to 1.038m, the storage capacity of Li Xing Reservoir will increase by 1.29 million m3, the available water supply will increase by1.7000 m3, and the single storage capacity will increase by1. It is 6,329,200 yuan less than that of 1038m normal water level scheme, but the available water supply of 1036m normal water level scheme is 65,438+700,000m3 less than that of 1038m normal water level scheme. The total investment of 1040m normal water level scheme is 4,382,400 yuan more than that of 1038m normal water level scheme. Therefore, considering the geological conditions of the dam site, engineering investment, water consumption and other factors, the normal water level is recommended to be 1038m at this stage, and the corresponding storage capacity is/kloc-.

3.2 Calculation of Water Conservancy Regulation

According to the irrigation area, field-soil ratio and crop composition of the project, the irrigation quota of the corresponding crop in the corresponding year is used for long-term series calculation. Magou Reservoir has not been fully regulated for many years, and the calculation period is ten days from May to August, and other months are months. The water utilization coefficient of canal system in irrigation area is 0.70, that of field is 0.95 and that of irrigation is 0.665. After calculation, the average irrigation water consumption in the irrigation area for many years is 6.5438+0.86 million m3, P=80%, and the irrigation water consumption is 2.65438+0.3 million m3. On the premise of ensuring the designed irrigation ground irrigation, Magou Reservoir can also solve the drinking water problem of 6,543,800 people, 300,000 large livestock and 6,543,800 small livestock in the irrigation area. According to relevant specifications, the per capita water consumption quota in rural areas is 0.075m3/d, and the water consumption quotas for large and small livestock are 0.050m3/d and 0.030m3/d respectively. It is planned to adopt channel water supply in the design.

4 General plan and main buildings of the project

4. 1 general layout of the project

The scale of this project is medium-sized, and the engineering grade is Grade III. The dam line of this project is unique. According to the topographic and geological conditions of the dam line, the dam line can adopt rigid dam or flexible dam with local materials. The general layout of the irrigation project of Magou Reservoir is as follows: the main reinforced concrete face rockfill dam, the auxiliary reinforced concrete face rockfill dam, the spillway on the left bank of the main dam, the diversion and emptying tunnel on the left bank, the diversion tunnel on the left bank and the canal system buildings in the south irrigation area, in which the maximum dam height of the main reinforced concrete face rockfill dam is 54.3m m.. The maximum dam height of the reinforced concrete face rockfill auxiliary dam is 18.8m, the normal storage level of the reservoir is 1038m, the dead water level is17m, the storage capacity below the normal storage level is 10400 m3, and the maximum storage capacity is1. The water intake tunnel is arranged on the left bank of the dam, with a flow of 3.84m3/s and a tower intake. The total length of the diversion tunnel is 808.44 meters, and the diversion tunnel is under pressure. The total length of canal system and building plane in irrigation area is 87. 14km.

4.2 Main Hub Buildings

The axis of the reinforced concrete face rockfill dam is located 20.0 meters downstream of the gravity dam axis. The calculated top elevation of the breakwater wall is 104 1.00 meters, the top elevation is 1039.80 meters, and the length of the dam axis is 159.65 meters .. The upstream and downstream slopes of the dam are all/kloc-. The width of the proposed dam crest is 7.0m, and the clear width is 6.0m. The elevation of the toe slab foundation surface of the riverbed section is 985.50m, and the maximum dam height is 54.30m The concrete impervious panel of this project is designed with the same thickness and the thickness is 0.45m；: Vertical joints are set on the panels, the tensile vertical joints are set on the panels near the two abutments with a spacing of about 6m, and the compressive vertical joints are set on the other panels with a spacing of 8.0m In this scheme, the toe board layout is that the toe board contour line is perpendicular to the "X" line. The toe slab is 0.5m thick and its width is determined according to the allowable hydraulic gradient of rock foundation. The toe slab width is 6.5m, and the riverbed and toe slabs on both banks are provided with an expansion joint every 12m ~ 15m. The overflow width is 12m, and the weir crest elevation is1033.0m. It is divided into two holes, and 6m×5m (width× height) flat steel gates are set respectively. The overflow weir is a WES type practical weir, which consists of an upstream surface curve, a downstream surface curve, an overflow section, an arc section and an underflow stilling basin section. The water intake of the water intake tunnel with a total length of+.5880.0665 is arranged about 300.0m away from the left abutment of the dam.

5 Engineering economic benefit analysis

The total investment of the project is 587.98 million yuan. The static investment is 587.98 million yuan, of which: ① the project investment is 33,449,438+0.3 million yuan; ② The investment of environmental migrants is 253,488,700 yuan; The basic reserve ratio is 5%; Loan interest is not calculated during the construction period. After calculation, the economic internal rate of return of this project is 8. 13%, which is more than 8%. The economic net present value is 7.48 million yuan, greater than 0; The benefit-cost ratio of 1.0 1 is greater than1; The payback period of investment is 13.7 years. The main economic indicators of economic analysis are greater than the basic requirements, and economic analysis is feasible. According to the survey, the per capita disposable income of farmers in irrigation area in 20 10 was 5 135 yuan/person, with an average annual increase of 5% from 20 1 14. It is predicted that the average disposable income in 20 14 years will be 624 1 yuan/. The water price for drinking water for people and livestock is calculated as 0.6%, and the annual per capita water supply is 30m3, and the water price is 1.23 yuan /m3.

The construction of this project can solve the present situation of drought and water shortage in the project area and overcome the water problem in practical projects. The irrigation project of Magou Reservoir is technically feasible and has remarkable economic benefits. The author thinks that it is a feasible method to solve the problem of water shortage irrigation by rationally arranging the project hubs, including reservoir dams and canals. The reservoir irrigation project can achieve reasonable economic benefits. This project provides a reference for similar projects in Cheng Kewei.

The above are collected and sorted by Zhong Da Consulting Company.

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