Analysis of groundwater resources and its environmental problems in Northeast China

Di Zhiqiang 1 Miao Ying 1 Jin 1 Jia Weiguang 1, 2

(1 Shenyang Institute of Geology and Mineral Resources, Shenyang,110032; 2 School of Resources and Civil Engineering, Northeastern University, Shenyang, 1 10004)

Based on the analysis of the present situation of water resources in Northeast China, it is calculated that the average water resources for many years are 1600.65× 108m3/a, the available water resources are 880.2 1× 108m3/a, and the exploitable groundwater resources are 483.08× 68m3/a. It is pointed out that water resources seem to have potential on the whole, but they do not match the distribution of population, cultivated land resources and economy, resulting in a considerable shortage of water resources in the country, and the foundation of sustainable utilization is already very fragile. The environmental problems caused by groundwater overexploitation in Northeast China are summarized as water shortage, serious water pollution, deterioration of ecological environment and ground deformation. The countermeasures of paying equal attention to the sustainable utilization of water resources and protecting and improving the natural environment are put forward.

Keywords: groundwater resources and environmental problems in Northeast China

order

Groundwater resource is one of the important natural resources for human survival and development, and it is an irreplaceable strategic economic resource for the sustainable development of national economy and society. Northeast China has a vast territory, although the total amount of water resources is relatively rich. However, the spatial and temporal distribution of water resources is extremely unbalanced, and the distribution of population, resources and productivity is seriously unbalanced, resulting in serious water shortage in some areas; The unreasonable development and utilization of groundwater resources has produced a series of environmental geological problems. It is of great significance to understand the present situation of water resources in Northeast China and analyze its environmental problems for revitalizing the old industrial base in Northeast China and supporting the sustainable development of regional national economy and society with the sustainable utilization of water resources.

1 current situation of water resources

The total amount of water resources is 1. 1

The average surface water resources in Northeast China are1134.65×108m3/a, the natural recharge resources of groundwater are 766.98× 108m3/a, and the repeated calculation of surface water and groundwater is 300.98×108m3.

Due to the influence of meteorological, hydrological, mountainous and hydrogeological conditions, the distribution of water resources in this area is extremely uneven. The maximum water resource in Heilongjiang Province is 653. 12× 108m3/a, and the minimum average water resource in Liaoning Province is 273.92×108m3/a. The order of water resources is Heilongjiang Province > Jilin Province > Eastern Inner Mongolia > Liaoning Province.

The per capita water resources in the whole region are only 1/8 of the world's per capita water resources, and 1/2 of the national per capita water resources, which is a moderately water-deficient area. According to the per capita water resources, the order is eastern Inner Mongolia > Heilongjiang Province > Jilin Province > Liaoning Province, in which Liaoning Province is a serious water shortage area.

Table 1 Statistical Table of Average Water Resources in Northeast China for Many Years (108m3/a) [1]

Note: Calculated according to 1999-2002 National Bulletin on Water Resources and Groundwater Resources in China —— A New Round of National Groundwater Resources Evaluation Results.

The annual average available water resources in the whole region are 880.2 1× 108m3/a, of which surface water resources are 397. 13× 108m3/a, and groundwater resources are 483.08×108m3/a.. ..

1.2 Present situation of water resources development and utilization

See Table 2 for the development and utilization of water resources in Northeast China. Because of the different population, industrial structure, city size and layout in different regions, the degree of water resources development and utilization is also different. From 1999 to 2002, the average utilization of water resources in Heilongjiang Province was the largest, which was 295.94× 108m3/a, and the average utilization of water resources in eastern Inner Mongolia was the smallest, which was 70 ∶ 34×108m3/a. The order of water resources utilization was Heilongjiang Province > Liaoning.

Table 2 Analysis Table of Water Resources Development and Utilization in Northeast China [1] Unit: 108m3/a

Note: Based on the data of 1999-2002 national water resources bulletin.

In recent years, in the development and utilization of water resources in Northeast China, the utilization of surface water is decreasing, while the exploitation of groundwater is increasing, but the total amount of water resources development and utilization is decreasing (Figure 1).

Figure 1 Analysis Diagram of Water Resources Development and Utilization in Northeast China

Generally speaking, there is still potential for the development and utilization of water resources in this area. However, the regional distribution is extremely unbalanced and does not match the population, cultivated land resources and economic distribution. Therefore, a considerable area of land is short of water resources, and the foundation of sustainable utilization is already very fragile.

2 Analysis of environmental problems

2. 1 Water shortage

With the intensification of productive economic activities and the sharp increase of urban (town) population, the shortage of urban (town) water supply has become an important problem restricting economic development. Many cities in Northeast China regard groundwater as an important or even the only water supply source. The improvement of urbanization level expands the demand for water resources, which leads to the shortage of urban water resources, groundwater overexploitation and groundwater environmental problems.

Due to the unreasonable exploitation of groundwater in some areas, the groundwater level continues to decline, forming a regional groundwater level decline funnel. Moreover, the area of the falling funnel continues to expand to the periphery, which has a negative impact on the normal circulation of water resources. Leading to paralysis of some water supply sources and some water supply wells [2]. In 200 1 year, the rainfall in northeast China is generally less, and the exploitation in major cities increases, resulting in a sharp drop in groundwater level. Compared with 2000, the decline in most areas is about1m.

The average annual water resources in Anshan City, Liaoning Province is 35.7 1× 108m3, and the urban per capita water resources are 126m3, which is only 1 1% of the world's per capita water resources. The average annual total water resources in Benxi City is 4.36× 108m3, and the per capita water resources are only 45 1m3. In addition, unreasonable utilization destroys the groundwater flow field and wastes groundwater resources. For example, the annual displacement of Fushun West Open-pit Mine is 3000×104 ~ 4000×104m3, and that of Laohutai Mine is 700×104 ~ 900×104m3.

Daqing is poor in surface water resources. The allowable exploitation of groundwater is 2.3× 108m3/a, and the current water consumption has reached 3.9× 108m3/a, and groundwater is over-exploited. Local over-exploitation of groundwater leads to the continuous decline of water level and the formation of groundwater falling funnel. The influence area of the falling funnel is 5560km2, and the water level is 45m, which is 0.96m lower than that in the initial stage of mining.

At the same time, the deterioration of groundwater quality has further aggravated the shortage of water resources.

2.2 The water environment is seriously polluted.

Due to the increase of industrial and domestic sewage discharge and the extensive use of pesticides and fertilizers, the problem of water environmental pollution has become increasingly prominent. According to incomplete statistics, in 2002, the total discharge of three wastes in Songliao basin was 62.87× 108t, including 32.75× 108t in Songhuajiang basin and 30. 12× 108t in Liaohe basin. The discharge of "three wastes" has seriously polluted the water quality of Songhua River and Liaohe River Basin. The main pollutants in surface water are ammonia nitrogen, nitrate nitrogen, petroleum, volatile phenol, cyanide, arsenic, mercury and biochemical oxygen demand.

According to the data analysis, the total length of the river evaluated in 2002 was 14869.4km, which met the Class I and II water quality standards of surface water and only accounted for 10% of the total length of the river. The length of rivers with Class III water quality is 50 17.6km, accounting for 34% of the total length of rivers; The length of rivers with water quality above Grade IV is 84 13.5km, accounting for 56% of the total length of rivers. Visible surface water quality is generally poor. Moreover, the monitoring results in recent years show that the water quality of Class I, II and IV is declining, while the water quality of Class III is rising (Figure 2).

Fig. 2 Variation curve of surface water level in Northeast China

With the pollution of surface environment, groundwater pollution is becoming more and more serious. Serious areas are mainly distributed around towns, surface polluted water distribution areas and polluted agricultural irrigation areas; The environmental pollution of groundwater is expanding from point to area and from city to countryside. The main pollutants in shallow water are ammonia nitrogen, nitrate nitrogen, petroleum, volatile phenol, cyanide, arsenic and mercury. The content of groundwater mostly exceeds the drinking water standard.

At present, there are more than 20,000 oil wells in Daqing Oilfield, and the new water injection technology is adopted. After the extracted oil-water mixture is preliminarily separated and purified on the surface, a part of water is re-injected into the ground, and oily water enters the phreatic layer, causing groundwater pollution; Part of water and industrial and domestic sewage are discharged into the surface water body, causing surface water pollution. At the same time, the surface water and groundwater permeate and replenish each other, resulting in groundwater pollution.

The chemical types of groundwater in Fushun city have changed the natural state under the action of human activities, from bicarbonate type to sulfuric acid type, bicarbonate sulfuric acid type, sulfate chloride type and other compound types. The highest value of SO4-2 is 1 1449.5mg/l, which is 4 1.8 times higher than the standard and 80.6 times higher than the background value. The content of NO3- is as high as 7 14. 15mg/l, which exceeds the standard by 8. 1 times, which is 22 times higher than the background value. The highest salinity is 25,283 mg/L, which is 25.3 times higher than the standard and 5 1.4 times higher than the background value. Coal gangue piled in a large area is polluted by precipitation, leaching and infiltration. The change of groundwater flow field accelerates the diffusion of pollutants, and the pollution of groundwater is more serious. According to the monitoring and analysis, in the area from Xinqiu to Hanjiadian, south of Daxin line railway in Fuxin mining area, the hydrochemical type of groundwater has gradually changed from the original bicarbonate water to calcium bicarbonate water, bicarbonate water and calcium sulfate water. The total hardness of groundwater around coal gangue hill in Xinqiu open-pit mine is as high as 2 170mg/ 1, and the sulfate is as high as 7 10mg/l, far exceeding the background value.

The over-exploitation level of groundwater in Dalian, Yingkou and other coastal areas decreased, which destroyed the pressure balance between fresh groundwater and seawater, caused seawater intrusion, and led to the deterioration of groundwater quality.

2.3 deterioration of ecological environment

The decline of regional groundwater level also reduces ecological water consumption, wetlands shrink or disappear, surface vegetation is destroyed, and land desertification leads to ecological environment degradation. Compared with the same period in 2002 1999, the groundwater depth in Honghe nature reserve decreased by about 1.2m[3] on average. The decline of water level intensifies the exchange between wetland water and groundwater, which makes wetland water replenish groundwater in large quantities, reaches a new water balance, and causes the wetland area to decline. The original wetland area in Heilongjiang Province is 850× 104ha, and the existing wetland area is 434× 104ha[4]. Another example is the grassland area in Songnen Plain, which was 280× 104 ha in the early 1960s, and decreased to 223.3× 104ha in the 1980s, with an average annual decrease of 1.87× 104ha. At present, the area of desertified land in Songnen Plain has reached 5960km2, and it is still expanding at the rate of 100km2 per year [5].

The water quality of rivers is seriously polluted, and wetlands are also facing serious threats.

A lot of pesticides and fertilizers are used in farmland, and soil and water are polluted. According to statistics, the annual application amount of chemical fertilizers and pesticides in Sanjiang Plain is about 32× 104t and 0.46× 104t[6]. As pests and diseases occur from time to time, it will further increase the dosage of pesticides, thus polluting water and soil.

With the migration of pollutants in the process of water cycle, the water and soil of wetland are polluted, which leads to the decline of wetland function and further deterioration of ecological environment.

2.4 ground deformation

The Quaternary system in the plain area is relatively thick and soft in structure. In addition, the continuous over-exploitation of groundwater in recent years has formed a large area of groundwater level drop funnel. When the local water level drops below the roof of the aquifer, the hydrostatic pressure decreases, which destroys the stress structure of the aquifer and produces the compression deformation of the soil mass, thus causing the ground subsidence. Ground fissures are caused by uneven settlement. In the building area of Daqing No.1 Oil Production Plant, the foundation of individual buildings sank more than 20cm [7].

3 countermeasures

3. 1 Overall Planning and Scientific Management

According to the temporal and spatial distribution characteristics of water resources, the carrying capacity of water resources and environment, combined with the needs of regional development layout of national economy and ecological environment construction, the sustainable utilization of water resources and the coordinated development of population, resources, environment and economy are the goals. Overall planning the development, utilization and protection of water resources, and establishing a scientific management system and technical support system to realize the sustainable utilization of regional water resources.

3.2 Joint storage, overall consideration

Water resources regulation and storage should implement the strategy of joint regulation and storage of surface and underground, and adhere to the principle of overall consideration of surface water and groundwater resources and water use in the upper, middle and lower reaches. Give full play to the respective advantages of surface reservoirs and underground reservoirs, and comprehensively develop and utilize water resources. The development and utilization of water resources must give consideration to the ecological environment and water use, so that water and natural resources can be recycled and used permanently.

3.3 Open source and reduce expenditure, comprehensive utilization

Rational development and utilization of water resources and comprehensive conservation of water resources are important measures to achieve the goal of sustainable utilization of water resources. Give priority to water saving, adjust industrial structure, improve water resources utilization efficiency, develop water-saving industries and build a water-saving society; It is necessary to open sources scientifically and through multiple channels, vigorously advocate the development and utilization of rainwater, seawater and brackish water, implement differentiated water use, comprehensively utilize water resources, and realize the recycling of sewage.

3.4 Optimize the environment and protect water resources

The natural environment is the cradle of life, and the environmental quality directly affects the survival and development of human society. Sustainable development should be based on protecting the natural environment and coordinated with the carrying capacity of resources and environment. The availability of water resources includes water quality and quantity. Without qualified water quality, there is no water quantity. Optimizing the natural environment and protecting water resources are the keys to realize the sustainable utilization of water resources.

It is necessary to educate the whole people on the values of water resources and awaken the public's awareness of environmental protection; Strengthen environmental protection, improve and optimize the environment, protect water resources and achieve harmony between man and nature.

It is necessary to rely on scientific and technological progress, strengthen the comprehensive management of pollution sources, start from the source, strictly limit waste discharge, protect water resources, and pay equal attention to development, utilization, protection and improvement.

4 conclusion

Northeast China has a vast territory, and the average water resources for many years is1600.65×108m3/a; The available amount of water resources is 880.2/kloc-0 /×108m3/a; Among them, the exploitable amount of groundwater is 483.08×108m3/a; /a； At present, the exploitation amount of groundwater is 266.69× 108m3/a/a, and the difference of natural conditions in different regions leads to significant differences in water resources richness. Generally speaking, water resources seem to have potential, but the distribution in the region is extremely unbalanced, which does not match the distribution of population, cultivated land resources and economy. Overexploitation of groundwater has caused environmental problems such as water shortage, serious water pollution, deterioration of ecological environment and ground deformation, and the foundation of sustainable development is already very fragile. To realize the sustainable development of national economy and society, we must take comprehensive measures to improve the utilization efficiency of water resources, optimize the natural environment and pay equal attention to development, utilization, protection and improvement on the premise of sustainable utilization of water resources.

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