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Environmental·Microbiology

AbstractBased on the evaluation data of groundwater resources and the demand for water resources in the construction planning of Ningdong Energy and Chemical Base, a joint water supply plan for surface water and groundwater was proposed, and a linear programming model was used to optimize the joint water supply plan, which determined the actual quota and water supply route in the water supply plan. The results showed that Taole riverside water source could supply 0.065×108 m3/a of water to Pingluo Fine Chemical Base; Luotuojing emergency water source can could 0.019×108 m3/a of water to Hengcheng and Yuanyanghu Industrial and Mining Area; the No.2 and No.3 alternative water sources of Wuzhong Plain could supply 0.089×108 m3/a and 0.067×108 m3/a of water to Lingwu Industrial and Mining Area; No. 1 water source of Daquan area could supply 0.054×108 m3/a of water to Majiatan and Jijiajing Industrial and Mining Area in the south. According to the total water supply volume of 0.294×108 m3/a and the optimal water supply route, the groundwater quota is only 3.136×108 m3/a, which can not only meet the demand for water resources of the Ningdong Energy and Chemical Industry Base in 2020, but also can maximize the socioeconomic and environmental benefits. The research could provide foundation basis for the economic and efficient utilization of water resources in the Base, and also provide references for the rational utilization of water resources in the industrial base of the arid area.

Key wordsWater resources; Optimal allocation; Ningdong Energy and Chemical Base

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Received: June 20, 2018Accepted: October 11, 2018

Lei FAN (1985-), male, P. R. China, engineer, Ph.D., devoted to research about water resources and environment.

*Corresponding author. Xingping FENG (1960-), male, P. R. China, senior engineer, devoted to research about soil and water conservation ecological project planning and design, E-mail: 1059688801@qq.com.

Ningdong Energy and Chemical Industry Base (hereinafter referred to as "Ningdong Base") is located in the middle east of Ningxia Hui Autonomous Region. With a total area of about 3 500 km2, it is 130 km long from north to south and 50 km from east to west, covering 4 counties (districts) of Lingwu City, Yanchi County, Tongxin County and Hongsibao Development zone. Coal resource in the Base is featured by large reserve, complete variety, excellent quality and favorable development condition. The proved coal reserve in the Base reaches 1 394.3×108 t, and the prognostic coal reserve in the long terms is 139.4 billion tons, making it one of the 13 national 100 millionton coal production bases in China. Located above the Lingyan terrace on the western edge of the Ordos Basin, the Base is extremely poor in water resources. The water supply sources in the Base are quite limited with most of the water supply coming from the Yellow River diversion, and a small amount coming from the groundwater of Wuzhong Plain. The Yellow River diversion is not only costly, but also susceptible to pollution. The water delivery is seasonal and the degree of protection is low. Therefore, how to use water resources efficiently is an important issue facing the construction of the Base, and has received extensive attention from all walks of life. At present, the literature research only gives the allocation quantity of various types of water (Yellow River water, mine dewatering water, treated sewage) at the Base, and proposes measures like treatment and utilization of mine water and various types of wastewater as well as water conservation to solve the water supply problems of the Base［1-2］. However, there is still no research involved with the joint use of surface water and groundwater in the Base as well as the optimal allocation of water resources. Therefore, it is still lacking in the research on the actual guidance of the rational and efficient development and utilization of water resources in the Base, which is necessary to carry out indepth research. Based on the groundwater resources evaluation data of the "Energy Base Groundwater Exploration in Ordos Basin (Ningxia)", the joint water supply plan of surface water and groundwater was proposed in combination with the water resources demand of construction planning in Ningdong Base, and the linear programming model was used to optimize the water supply plan, so as to provide fundamental bases for the economic and efficient utilization of water resources in the Base, and references for the economic and reasonable utilization of water resources in the industrial bases in arid regions.

Water Demand and Current Water Supply Status of Ningdong Energy and Chemical Base

Industry planning of Ningdong Energy and Chemical Base

According to the overall plan, the Base prioritizes the development of 3 dominant industries, namely, coal, power and coal chemical industry, added with extended development of the downstream industries of petrol and gas chemicals, fine chemicals, materials industry and other service industries. The coal mining area includes 3 mining areas of Lingwu, Yuanyanghu and Hengcheng, and 12 well fields. The power plants include Maliantai Power Plant, Lingzhou Coal Gangue Comprehensive Power Plant, Lingwu Power Plant, Yuanyanghu Power Plant, Shuidonggou Power Plant, Fangjiazhuang Power Plant and Zaoquan Power Plant. The 3 industrial parks are Coal Chemical Park, Linhe Comprehensive Project Area and Lingzhou Comprehensive Project Area. Pingluo Fine Chemical Base has been built in the boundaries of northeastern Ningxia and Inner Mongolia. The geographical location and the distribution of major factories and mines are shown in Fig. 1.

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Fig. 1Distribution of factories and mines in Ningdong Energy and Chemical Base

Water demand of Ningdong Base

The major water demand in the Base is mainly the demand for fresh water for the coal mine production and living, power plant production and living, and coal chemical projects. According to the "Ningdong Base Overall Plan and Construction Outline", the total water demand in 2020 will reach 3.43×108 m3/a, of which 0.16×108 m3/a is for coal mine production and living, 0.29×108 m3/a for power plant production and living, and 2.98×108 m3/a for coal chemical production, in which the water consumption for coal chemical project is the largest. The water demanded for environmental protection and greening can be solved by treatment or recycling of pit water and industrial wastewater.

Yellow River diversion project and emergency water source demand of Ningdong Base

Yellow River diversion project

Ningxia has built 2 water diversion reservoirs in accordance with the base plan: Yazidang Reservoir and Liujiagou Reservoir. Among them, Yazidang Reservoir is located in the north of the Base, and its water supply can reach 3.0×108 m3/a in 2020; Taiyangshan Water Supply Project (Liujiagou Reservoir) is located in the south of the Base, and the water supply is 0.36×108 m3/a. The water sources of these 2 reservoirs are all from the Yellow River and are transported through special pipelines. The quota of water comes from the replacement of water rights, that is, the balance generated by water conservation in agriculture is allocated to industrial water.

Emergency water source demand

The emergency water source firstly is to guarantee the demand for fresh water for the production and living of coal mines and power plants. In other words, in 2020, 0.16×108 m3/a of water is for the production and living of coal mines, and 0.29 ×108 m3/a of water is for the production and living of power plants, totaling 0.45×108 m3/a. The water demand for coal chemical projects is temporarily not included in the guarantee scope of emergency water supply.

Materials and Methods

Based on the groundwater resources evaluation data (2014) of the "Energy Base Groundwater Exploration in Ordos Basin (Ningxia)", statistical and graphic methods are used to analyze the exploitable water amount of the groundwater sources and the emergency water supply capabilities of surrounding water sources which can supply water for the Base. The joint water supply plan of surface water and groundwater is expressed by means of topographic map, and the linear programming model is used to optimize the joint water supply plan, and to determine the actual quota and water supply routine of groundwater in the water supply plan.

Results and Analysis

Groundwater source and its water supply potential

At present, there are 5 groundwater sources that have been proven to be able to supply water to Ningdong Energy and Chemical Industry Base. The statistics on the exploitable amount of groundwater in each water source are shown in Table 1, and the summary of the exploitable amount of alternative emergency water sources is shown in Table 2. The water supply capacities of the above water sources are plotted into a block diagram (Fig. 2).

As shown in Fig. 2, in the west, Luotuojing area of Yanchi can supply 0.046×108 m3/a for Ningdong Base, Lingwu area in the east can supply 0.465×108 m3/a of water, and Taole area in the north can supply 0.113×108 m3/a of water. The total engineering exploitable amount is 0.624×108 m3/a, which can meet the demand for emergency water supply of 0.450×108 m3/a of the Base in 2020. The emergency water supply for longer term may need to make use of brackish water, and treatment of brackish water should be considered.

Table 1Statistics of groundwater recoverable in Ningdong Energy and Chemical Base

Water sourceCurrent exploitation amount∥×108 m3/ aEngineering exploitable amount∥×108 m3/aWater quality

Luotuojing water source0.0180.046Freshwater

Lingwu Daquan water source0.0900.270Freshwater

Lingwu Chongxing water source0.0400.070Freshwater

Taole plain water source0.0100.113Freshwater

Wuzhong plain riverside water source00.246Freshwater

Table 2Summary of exploitable amount of alternative emergency water sources in Ningdong Energy and Chemical Base

RegionWater sourceNumber ofwells Exploitable amount×104 m3/dSingle well exploitableamount∥m3/dAnnual exploitableamount∥×108 m3/aDifficult to restoreddrawdown∥m

Taole plainRiverside water source103.103 1000.1131.100

Wuzhong PlainNo. 1 water source94.675 1890.1700.840

No. 2 water source64.207 0000.1530.573

No.3 water source52.555 1000.0930.240

Salt pondLuotuojing101.251 2500.0461.230

Total15.77-0.576-

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The data in parentheses is the existing exploited amount (×108 m3/ a)

Fig. 2Block diagram of emergency water supply capacity of water sources near Ningdong Energy and Chemical Base

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Fig. 3Topological plan of joint water supply plan for surface water and underground water at Ningdong Energy and Chemical Base

Xingping FENG et al. Study on Optimal Allocation of Water Resources in Ningdong Energy and Chemical Base

Joint water supply plan of surface water and groundwater

According to the overall plan of the Ningdong Energy and Chemical Base, the water for the energy and chemical enterprises is mainly provided through Yazidang Reservoir and Liujiagou Reservoir. The Yellow River diversion projects rely on the Yellow River and its affiliated water conservancy facilities, so the water delivery is seasonal. Thus, it is necessary to build reservoirs or large water blocking pits and to treat sedimentation. However, in this way, the cost of water supply and maintenance operations is high, and the great losses of water resources can be caused by evaporation and leakage. Moreover, the surface water is susceptible to pollution and the degree of protection is low. On the other hand, after proving the groundwater sources, the introduction of proper groundwater supply projects can reduce evaporation losses and operating costs, and serve as an emergency water supply. However, the existing groundwater sources alone cannot meet all the fresh water needs of the Base. Therefore, the joint water supply scheme of surface water and groundwater is more conducive to the efficient development and utilization of regional water resources. After analysis and research, the joint water supply plan for surface water and groundwater in Ningdong Energy and Chemical Industry Base is proposed, which is as shown in Fig. 3. The main points of the plan are as follows:

(1) The water source of Taole supplies water separately to Pingluo Fine Chemicals Base. Pingluo Fine Chemicals Base is located at the northern end of the Taole area, and the current water supply measures there are to divert water from the Yellow River to the industrial zone via water supply pipes and pumping stations. The planned water supply of Pingluo Fine Chemicals Base is 20 000 m3/d (0.073×108 m3/a), while the exploitable amount of riverside water sources of Taole reaches 0.113×108 m3/a, which can meet the water demand of Pingluo Fine Chemicals Base.

(2) Water is supplied to Hengcheng industrial and mining area and Yuanyanghu industrial and mining area through the combination of constructing water pipelines and water delivery stations with Luotuojing emergency water sources. The water supply of Luotuojing emergency water source is 0.046×108 m3/a.

(3) In Lingwu area, water delivery stations and water supply pipelines are constructed to supply water for Hengcheng industrial and mining area with the combination of No.3 riverside water source and Yazidang Reservoir. In addition, a water delivery station is built to connect the existing Chongxing water source and No.2 alternative water source with the water supply pipes of Yazidang Reservoir, so as to provide water for the production and living of the coal mines and power plants in Lingwu industrial and mining area. In such plan which operates jointly with Yazidang Reservoir, the groundwater supply can reach up to 0.276×108 m3/a. On the other hand, Yazidang Reservoir can supply fresh water for the coal chemical projects in Ningdong Base, and the planned water supply capacity can reach 2.980×108 m3/a in 2020, in which the groundwater supply accounts for only a small proportion.

(4) In the southern part of Lingwu, Daquan water source and No.1 alternative water source work jointly with the surface water from Liujiagou Reservoir to supply water for Jijiajing and Majiatan industrial and mining area. The planned fresh water amount is 0.054×108 m3/a for Majiatan and Jijiajing mining area in 2020, which is lower than the water supply capacity of Liujiagou Reservoir. The total water supply of Daquan water source and No.1 water source is 0.189×108 m3/a, which is larger than the water demand of Majiatan and Jijiajing mining area. Therefore, the remaining water can be distributed to the north to Lingwugong mining area.

Optimization of water supply plan for Ningdong Energy and Chemical Industry Base

The above discussion proposes a joint water supply plan for surface water and groundwater in Ningdong Energy and Chemical Industry Base, and determines the water supply route and the maximum possible water supply capacity of the surrounding groundwater sources, but there is still much uncertainty left, that is, the actual groundwater supply scale to be a economically reasonable plan. In order to quantitatively determine the water supply quota in the plan, the linear programming model is used for the analysis.

Model equations

The basic idea of optimizing the joint water supply plan for surface water and groundwater in Ningdong Energy and Chemical Industry Base is to achieve the water supply target with the lowest economic cost. Since the water supply scheme for quoting the Yellow River water has already been planned and the construction of the project has been partially completed, consideration is no longer given to the infrastructure investment in surface water supply projects, but mainly to the infrastructure investment and operating costs for groundwater supply projects.

The total amount of water supply depends on the demand, and it should satisfy the following relation:

Q1+Q2=Qx(1)

Where, Q1 is the effective water supply amount of surface water; Q2 is the groundwater supply amount; Qx is the required total water supply amount. Assume the diversion amount of surface water is Qs, considering the loss of evaporation and leakage, the effective surface water supply amount and the amount of water diversion should have the following relation:

Q1=(1-η)Qs(2)

Where, η is the loss coefficient. According to the relevant data of Yazidang Reservoir, η can be 3.3% (from the "Water Resources Argument Report for Phase I Water Supply Project of Ningdong Energy and Chemical Industry Base").

The water loss is a waste of water resources, and the following penalty function is introduced:

Jw=(qs+esηQs)=qs+esη1-ηQ1η1-ηQ1(3)

Where, Jw is the penalty cost introduced in the model; qs is the water right replacement cost for unilateral water; es is the multiplication function of the penalty (that is, the unilateral cost of each additional waste of 1 m3 of water). According to the experience of water rights replacement in Ningxia, qs=2.0 Yuan/m3. es can be 0.01 Yuan/10 000 m3, which means that the unit price of each additional waste of 10 000 m3 of water is increased by 0.01 Yuan.

Both groundwater and surface water supplies need to meet the following constraint condition:

Q1≤QR; Q2≤Qp(4)

Where, QP is the exploitable amount of groundwater; QR is the water supply capacity of the surface reservoir.

For any groundwater source, the exploitation amount can cause pressure for local water supply and ecological environment, and the unilateral cost of water rights replacement increases with the increase of the ratio of actual production to exploitable amount (increase of environmental pressure). The formula is as follows:

Mp=qg1+3Q2QpQ2(5)

Where, qg is the basic water rights replacement unilateral cost of groundwater (2.0 Yuan/m3).

The total economic cost is calculated as follows:

Jx(Q1, Q2)=JW+MpΔt+qsQ1(1-η)Δt+qeQ2LgΔt+msQ1+mgQ2(6)

Where, t is the investment recovery period considered by the model (20 years); qsQ1 is the water right replacement cost of surface water; qe is the unilateral cost of infrastructure investment for groundwater supply project［0.04 Yuan/(m3?km)］; Lg is the water transport distance; ms is the operating water delivery cost of the surface water supply project (1.5 Yuan/m3); mg is the operating water delivery cost of the groundwater supply project (1.0 Yuan/m3).

The objective function of the planning model is as follows:

Jx=min Jx (Qs,Qg)(7)

In other words, the total cost of the joint water supply plan can reach the lowest in 20 years.

Model solution

The water supply plan in Fig. 3 can be divided into several components to solve the respective optimized models before summary.

Optimized water supply plan in Taole area

The water demand Qx of Pingluo Fine Chemical Base in Taole area is 0.073×108 m3/a, and the engineering exploitable amount of Taole water source QP is 0.113×108 m3/a. At present, the water supply of Sankeliu Water Diversion Project fro the Yellow River QR is 0.055×108 m3/a, and the water delivery distance Lg is 40 km. The results obtained by the model solution are shown in Fig. 4.



Fig. 4Variation curve of economic cost of water supply scheme in Taole area

As shown in Fig. 4, with the increase of groundwater supply amount, the economic cost of water supply generally shows a downward trend. When the groundwater supply reaches 0.065×108 m3/a, the cost of water supply is reduced to the minimum. The exploitable amount of Taole riverside water source reaches 0.113×108 m3/a, but it can satisfy the optimal water supply target by exploiting only 0.065×108 m3/a of water. In this way, it only needs 0.008 ×108 m3/a of surface water.

Optimized water supply plan for the central industrial and mining area

The central industrial and mining areas includes Hengcheng Industrial and Mining Area, Lingwu Industrial and Mining Area and Wuhu Industrial and Mining Area. The total water demand Qx of the joint water supply is 0.396×108 m3/a, and the surface water supply project is Yazidang Reservoir. Except for the water supply to the coal chemicals, the remaining water supply capacity is 0.256×108 m3/a. There are 4 groundwater sources, namely, Luotuojing emergency water source, existing Lingwu Chongxing water source, No.3 alternative water source and No.2 alternative water source, and the total amount of water supply can reach 0.352×108 m3/a. First, it should make optimization selection of the total amount, and then allocate the water supply amount according to the water supply capacity of each water source. The average water delivery distance is calculated as 0 km, and then the results from the model solution are shown in Fig. 5.

As shown in Fig. 5, with the increase of groundwater supply amount, the economic cost of water supply generally shows an upward trend, but when the groundwater supply reaches 0.175×108 m3/a, the cost of water supply is reduced to the minimum. Since the total water demand Qx of the joint water supply in the central mining area is 0.396×108 m3/a, the optimal water supply plan should be 0.175×108 m3/a for the total groundwater supply and 0.245×108 m3/a for the surface water supply amount. Among these water sources, the water source of Chongxing is already the water source of Lingwu City, and it cannot be used as the water source for emergency water supply in Ningdong Base. The No. 2 water source and the No. 3 water source are divided according to the water supply capacity and the water supply distance. The following water exploitation scheme is recommended: Luotuojing emergency water source of 0.019×108 m3/a (accounting for 41% of the exploitable amount), No.2 alternative water source of Lingwu Plain of 0.089×108 m3/a (accounting for 58% of the exploitable amount); No. 3 alternative water source of Lingwu Plain of 0.067×108 m3/a (accounting for 72% of the exploitable amount).



Fig. 5Variation curve of economic cost of water supply scheme in Central Industrial and mining area

Optimized water supply plan for the southern industrial and mining area

The southern industrial and mining areas include Majiatan Industrial and Mining Area and Jijiajing Industrial and Mining Area. The total water demand Qx of the joint water supply is 0.054×108 m3/a, and the surface water supply project is Liujiagou Reservoir, which has a water supply capacity of 0.061×108 m3/a. The groundwater sources are Daquan Township water source and No. 1 alternative water source. The emergency water supply is 0.189×108 m3/a, and the water transfer distance is 50 km. The results obtained by the model solution are shown in Fig. 6.



Fig. 6Variation curve of economic cost of water supply scheme in the southern industrial and mining area

As shown in Fig. 6, the use of groundwater can reduce the cost of water supply, and the cost is the lowest when only using groundwater. The exploitable amount of Lingwu No.1 alternative water source is 0.170×108 m3/a, which exceeds the water demand of the southern industrial and mining area. Therefore, it can use the water from No.1 alternative water source only, and the emergency water supply amount is 0.054×108 m3/a, accounting for only 32% of the exploitable amount.

The actual water supply route and water supply quota for groundwater in the joint water supply scheme

In order to achieve the goal of realizing water supply with the lowest economic cost, optimization is made to the joint water supply plan for surface water and groundwater, and the actual water supply routes and water quota of groundwater is shown in Table 3.

According to the total water supply volume of 0.294×108 m3/a and the optimal water supply route, the groundwater quota is only 3.136×108 m3/a, which can not only meet the demand for water resources of the Ningdong Energy and Chemical Industry Base in 2020, but also can maximize the socioeconomic and environmental benefits.

Table 3Actual water supply routes and water quota for joint water supply plan

Water sourceWater supply routeWater supply quota∥×108 m3/ a

Taole riverside water source Pingluo Fine Chemical Base0.065

Luotuojing emergency water sourceHengcheng and Wuhu Industrial and Mining Area0.019

Wuzhong No. 2 alternative water sourceLingwu Industrial and Mining Area0.089

Wuzhong No. 3 alternative water sourceLingwu Industrial and Mining Area0.067

The No. 1 water source of the Daquan areaMajiatan and Jijiajing Industrial and Mining Area0.054

Conclusion

(1) In this study, the joint water supply plan for surface water and groundwater is proposed for Ningdong Energy and Chemical Base, and the linear programming model is used to optimize the joint water supply plan. The actual water supply routes and water quota are determined according to the optimized plan as follows: Taole riverside water source can supply 0.065×108 m3/a of water to Pingluo Fine Chemical Base; Luotuojing emergency water source can supply 0.019×108 m3/a of water to Hengcheng and Yuanyanghu Industrial and Mining Area; the No.2 and No.3 alternative water sources of Wuzhong Plain can supply 0.089×108 m3/a and 0.067×108 m3/a of water to Lingwu Industrial and Mining Area; No. 1 water source of Daquan area can supply 0.054×108 m3/a of water to Majiatan and Jijiajing Industrial and Mining Area in the south.

(2) According to the total water supply volume of 0.294×108 m3/a and the optimal water supply route, the groundwater quota is only 3.136×108 m3/a, which can not only meet the demand for water resources of the Ningdong Energy and Chemical Industry Base in 2020, but also can maximize the socioeconomic and environmental benefits.

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