Research and Countermeasures on Groundwater Resources and Environment in Inner Mongolia

(Department of Land and Resources of Inner Mongolia Autonomous Region, Hohhot, 0 10020)

On the basis of expounding the hydrogeological conditions, aquifer types and groundwater distribution characteristics in Inner Mongolia Autonomous Region, this paper systematically evaluates the supply and demand of groundwater resources from two aspects of resource replenishment and groundwater development and utilization, and puts forward some countermeasures and suggestions for the problems existing in the current groundwater resources development process.

Keywords: groundwater resources and environmental problems

Since the beginning of 2 1 century, the problem of global water shortage has become very prominent. According to statistics, the national land area of 1/4 is short of water, and the water resources of10 can only meet the basic requirements of human survival. In normal years, the water shortage is nearly 400× 108m3. Unreasonable exploitation of water resources leads to a series of disasters and ecological environment problems, such as regional groundwater level decline, water depletion, large-scale land subsidence, vegetation death, wetland disappearance and so on. Groundwater pollution has spread to most cities in China. Due to the decline of groundwater quality, the water supply in more than 300 cities is tight, which has seriously threatened the sustainable development of economy and society. Efforts must be made to solve the sustainable utilization of groundwater resources, prevent the destruction of groundwater environment under the action of nature and man-made, and strengthen the protection and scientific and rational development and utilization of groundwater resources.

Inner Mongolia Autonomous Region is located in the frontier of the motherland, with a total land area of1104km2, accounting for 12.3% of the national total area, a population of 2,378.6x104, and groundwater resources of 321. Generally speaking, Inner Mongolia is not rich in groundwater resources, the regional surface water system is underdeveloped, and water resources are poor and unevenly distributed. The eastern and southeastern regions are rich in precipitation and groundwater resources, while the western and northern regions are poor in precipitation and groundwater resources. The shortage of water resources and its heterogeneity have seriously restricted the development of national economy in the autonomous region. Therefore, it is of great significance to fully understand the present situation of groundwater resources in Inner Mongolia, rationally develop and utilize groundwater resources, and actively explore new methods and new ways to solve the ecological environment problems of groundwater resources.

Hydrogeological conditions of 1

Inner Mongolia Autonomous Region basically belongs to plateau landform, but the landform, genetic types, stratigraphic lithology and geological structure in different inland areas are different. Accordingly, the groundwater in the whole region can be divided into seven hydrogeological areas: Daxinganling, Xiliaohe Plain, Northern Inner Mongolia Plateau, Yinshan, Hetao Plain, Ordos Plateau and Alashan Plateau.

1. 1 groundwater system division

Autonomy distinguishes inland and external water systems. The outflow water system is further divided into Ergon River, Xiliao River, Haihe River, Luanhe River and Yellow River. The internal water system is divided into Alashan Plateau and Yinshan Northern Plateau.

According to the surface water basin and geomorphological state in this area, the autonomous region is divided into 8 groundwater systems and 25 subsystems, and their geomorphological and hydrological characteristics are shown in table 1.

The recharge methods are mainly atmospheric precipitation, but also lateral runoff, yellow river infiltration, flood infiltration and surface irrigation; The main drainage methods are evaporation and lateral runoff, as well as valley drainage and artificial mining.

Table 1 Geomorphological Characteristics of Groundwater System

1.2 division of water-bearing rocks

According to the water-bearing medium and occurrence conditions of groundwater, the whole area can be divided into three kinds of water-bearing rocks, namely loose rock pore water, clastic rock fissure pore water and bedrock fissure water (including carbonate rock fissure cave water).

1.2. 1 loose rock pore water

Loose rock pore water is widely distributed in this area, mainly distributed in valleys, valley depressions, piedmont alluvial-diluvial inclined plains, mountain discontinuous (depressed) basins and desert areas.

1.2.2 clastic fissure pore water

Clastic fissure pore water is widely distributed in the autonomous region, mainly distributed in Ordos Plateau, northern Inner Mongolia Plateau, Alashan Plateau, some intermountain basins on the east side of Daxing 'anling Mountains and intermountain basins in the yinshan mountains.

1.2.3 bedrock fissure water

Widely distributed in the mountainous and hilly areas of the autonomous region, in addition, basalt fissure water is also distributed in the northern plateau of Inner Mongolia and Yinshan Mountain area.

1.3 groundwater distribution characteristics

Influenced by climate, geological structure and paleogeography, groundwater in Inner Mongolia has its own characteristics in quantity, quality and spatial distribution, mainly in the following aspects:

(1) Groundwater resources are characterized by less exploitable resources, uneven distribution of resources and relatively poor water quality.

(2) The groundwater is influenced by climate, and both the quantity and the quality change in a strip shape with the climate change. Mainly manifested in:

First, the water quantity is decreasing from east to west, and the water quality is getting worse.

Secondly, the distribution of aquifers in Quaternary valley gradually decreased from east to west, and the aquifers became thinner and narrower, and the water quality became worse.

Third, due to the decrease of precipitation from west to north, the original poor water was diluted and weakened from west to north.

Fourth, the recharge of deep groundwater gradually weakens from east to west.

(3) Due to the complex geological conditions, the hydrogeological conditions are complex and diverse.

(4) The occurrence conditions of groundwater are closely related to paleogeography.

(5) The hydrogeological characteristics of inland drought are obvious, which are as follows:

First of all, there is no unified circulation datum for groundwater.

Second, the Quaternary valley aquifer became thinner or disappeared from the upstream to the downstream of the valley, and the salt content of groundwater increased rapidly.

Third, the standard elements in arid climate are rich.

Fourth, the permeable aquifer is thick.

Fifth, Quaternary valleys are rare and short-lived.

(6) There are abundant fresh water resources in the lower part of the desert.

(7) There is the largest Cretaceous freshwater basin in China.

(8) Groundwater belongs to the most different water system, and the hydrogeological conditions of different water systems are also different, as follows:

First, the aquifer thickness and structure of Quaternary valley are different.

Second, the width of Quaternary valley is different.

Third, the groundwater development capacity is different.

(9) The geological environment of groundwater is mainly primary environment, and the secondary environment only exists in local areas, and the primary environment is poor.

2 Analysis of the present situation of groundwater resources

2. 1 surface water resources

The quantity and change of surface water resources are mainly controlled and influenced by precipitation in various places. The spatial distribution of precipitation in Inner Mongolia Autonomous Region gradually decreases from east to west, generally from 450 mm in Hulunbeier to less than 50 mm in Alashan League. At the same time, the annual precipitation is also decreasing from south to north, which makes the spatial distribution and change of surface water resources have the same law as the regional distribution and change of precipitation, that is, from east to west and from south to north.

The surface water resources in the whole region are not only small, but also unevenly distributed in space. Relatively speaking, the eastern part of Inner Mongolia Autonomous Region is rich in surface water resources, with an average of 335× 108m3/a for many years, accounting for 88.69% of the total surface water resources in the region. The average surface water resources of Haihe River and Luanhe River in central China are 3.93× 108m3/a, accounting for 1.04%. The surface water resources of the tributaries of the Yellow River system in the west are 19.85× 108m3/a, accounting for 5.26%. Ejina River in Alxa League accounts for 1.88% of the total water resources in the whole region. The remaining surface water resources in internal drainage are small and unstable. From the distribution of surface water in the year, runoff and precipitation are completely consistent, and most rivers in the central and western parts of the autonomous region have dry seasons, which increases many difficulties in the development and utilization of surface water.

2.2 Natural groundwater recharge resources

The average annual natural recharge resources in the whole region are 292.5242× 108m3/a, and the natural recharge resources in dry years are 243.8240× 108m3/a, as shown in Table 2.

The distribution law of groundwater natural recharge resources in the whole region is the same as that of atmospheric precipitation, and both of them have the law of decreasing from east to west and from south to north.

2.3 Present situation of exploitable groundwater resources

Groundwater exploitable resources refer to the amount of groundwater that can be exploited and utilized continuously under certain economic and technical conditions, and no serious environmental problems will occur during the mining process.

The exploitable resources of groundwater in Inner Mongolia Autonomous Region are149.5033x108m3/a, and the exploitable resources of each system are shown in Table 3.

Table 2 Statistical Table of Natural Resources in Normal and Dry Years Unit: 108m3/a

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Table 3 Groundwater resources by groundwater system statistics

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2.4 Water resources evaluation

Inner Mongolia Autonomous Region has less precipitation and large evaporation, and is not rich in surface water and groundwater resources.

According to the average for many years, the surface water resources in Inner Mongolia Autonomous Region are 377.7 1× 108m3/a (except the main stream of the Yellow River is 228.80× 108m3/a), of which 78.65× 108m3/a is the basic flow, and the available surface water resources are

The total water resources of surface water and groundwater are 583.20× 108m3/a, and the drought year is 534.50× 108m3/a, and the available resources of surface water and groundwater are 298.29×108m3/a. ..

2.5 Water shortage analysis

Inner Mongolia Autonomous Region covers an area of118.3×104km2/a, most of which are desert, arid and semi-arid areas, with poor surface water and groundwater, and the per capita exploitable resources are only 642m3/ (person a).

2.5. 1 shortage of drinking water for people and livestock

The water shortage area of Inner Mongolia Autonomous Region is 20. 13× 104km2/a, and the population is 234.6× 104. It is mainly distributed in Alashan Plateau north of Yinshan Mountain and Inner Mongolia Plateau, the basin composed of Tertiary and platinum between Yinshan Mountain, the limestone area around Qingshui River and Zhuozi Mountain and the western hilly area, especially in Alashan area in western Inner Mongolia. See Table 4 for details.

Table 4 Statistics of Water Shortage Areas in Inner Mongolia

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2.5.2 Water shortage in cities and towns

Water shortage in towns and important port cities in central and western Inner Mongolia Autonomous Region has seriously affected people's lives and restricted local economic development. See table 5 for details.

Table 5 Statistics of Urban Water Shortage

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3 Problems and Countermeasures

Inner Mongolia Autonomous Region has a vast territory, with great differences in hydrogeological conditions and extremely unbalanced groundwater resources. Especially in the past 20 years, the national economy has developed rapidly and maintained a high growth rate. The corresponding amount of groundwater development and utilization has also increased year by year, and the total amount of groundwater exploitation in some cities and counties has doubled. As far as the whole region is concerned, the main problems existing in the development and utilization of groundwater and the measures to be taken are reflected in the following aspects:

3. 1 The distribution of groundwater resources is inconsistent with the national economic layout, which makes the development of groundwater resources in the whole region inconsistent with the requirements of supply and demand.

With the further implementation of the country's western development, the contradiction between supply and demand in the central and western regions has become more prominent. Hohhot, the capital of the autonomous region, and Baotou, the largest industrial city in our region, are both located in the western region, especially the further development of the energy base in Ordos City, which has a greater demand for groundwater resources. In this regard, we should use the existing groundwater resources and take a series of water-saving measures. At the same time, it is necessary to control the ecological deterioration, restore the ecological environment, implement the west route project of South-to-North Water Transfer as soon as possible, and solve the water shortage problem in the central and western regions from the source.

3.2 The development of groundwater resources is unbalanced

The average degree of development and utilization of groundwater resources in the whole region is 40.04%. Baotou, Hohhot and Wulanchabu have almost no mining potential, while Xing 'an League, Tongliao, Bayannaoer, Erdos and Wuhai are all around 50%. Only Xilin Gol League, Hulunbeier City and Alashan League have groundwater exploitation levels around 10%, and there are still areas to be developed, such as Wulanbuhe Desert, Hunshandake Desert and Badain Jaran Desert.

3.3 insufficient attention has been paid to the achievements of groundwater exploration in the past.

Since the founding of the People's Republic of China, our region has done a lot of work in groundwater exploration, which has played a certain role in the national economic development planning. However, the distribution law of groundwater in different regions and the conditions of development and utilization are often ignored in decision-making, which also reflects that the results of hydrogeological exploration are not well combined with the macro-decision-making of national economy. Therefore, the exploration results should be changed from professionalism in the past to readability and visibility, and the results should be socialized to provide a basis for the macro-decision of government departments. Governments at all levels should make full use of the preliminary exploration data before macro-decision to avoid decision-making mistakes.

3.4 In the management of water resources, there is a lack of control means for rational utilization of groundwater resources.

First, the mixed exploitation of two different kinds of groundwater, diving and confined water, only seeks water quantity, not quality, so that the groundwater is interconnected, which not only changes the hydrodynamic conditions of groundwater, but also pollutes the confined water with good water quality. Second, the contradiction between industry and agriculture on water exists. Fragmentation, indiscriminate mining and excavation, lack of rationality and overall situation in development and utilization. Third, the layout of production wells is unreasonable, resulting in over-exploitation of groundwater and formation of local funnel. Fourth, the irrigation method is obsolete, which causes serious waste of groundwater resources.

3.5 The supervision of comprehensive utilization of surface water and groundwater is insufficient.

When considering surface water and groundwater resources comprehensively, there is a lack of reasonable distribution and utilization. For example, the formation of saline soil in Hetao Plain is not only caused by internal factors such as basin closure, poor groundwater runoff, vertical circulation of groundwater, climate drought and geological environment. Overirrigation of surface water, irrigation without drainage, and excessive leakage of canal system cause the groundwater level to rise, which is the external cause of soil salinization. To solve the problem of salinization in Hetao area, it is necessary to reduce the groundwater level. The influence range of canal drainage is too small, and the unilateral influence is only 300 ~ 500 m. However, canal drainage occupies a lot of land and the effect is not obvious. According to the irrigation area 1 1438 mu, there are at most 2,904 wells, and the irrigation water demand is 43.53× 108m3/a, of which groundwater 14.83× 108m3/a, so surface water and groundwater should be strengthened.

3.6 The protection of existing groundwater resources is insufficient, and the utilization of wastewater needs to be strengthened.

On the one hand, the arbitrary discharge of urban domestic and industrial wastewater causes different degrees of groundwater pollution and wastes groundwater resources; On the other hand, the confined water wells in some places have been self-flowing for a long time and have not been well utilized. In addition, the utilization rate of wastewater in the autonomous region is only 10% ~ 20%, so we should strengthen the sewage treatment to make the sewage discharge meet the national standards, improve the reuse rate and save water resources.

3.7 the use of groundwater resources to improve the ecological environment.

Desertification in the autonomous region is serious, sandstorms are increasing day by day, and grassland degradation is becoming more and more serious. Hunshandake Desert, Mu Us Desert, Kubuqi Desert, Wulanbuhe Desert, Badain Jaran Desert and Tengger Desert are all rich in groundwater resources. Therefore, we should strengthen exploration and development and promote the construction of ecological environment projects.

3.8 The exploration of groundwater resources lags behind the needs of national economic development.

The degree of groundwater exploitation in the whole region is low, and the average exploitation amount is 1m/km2. Among them, the exploration area above1:50,000 scale is 4× 104km2, accounting for only 3.5% of the autonomous region. The exploration area of farmland water supply with the scale of 1∶65438+ ten thousand is only 14× 104km2, accounting for 12% of the total area. Most of them are1:200,000 ~1:500,000 scale surveys and general surveys. They are in the stage of water exploration and investigation, so they can only make long-term regional planning, and it is difficult to solve specific practical problems. In reality, many problems related to groundwater need to be solved urgently. Such as human and animal water, industrial and agricultural water, ecological environment improvement, industrial structure adjustment, ecological migration and saline soil improvement are all closely related to groundwater.