Li Zhenghong¹  Sun Jichao¹  ZhangSheng¹  WangShan¹  Guo Xiuhong^2,1

1 Institute of Hydrogeology & Environmental Geology, Chinese Academy of Geological Sciences Shijiazhuang 050061;

2 School of Water Resources and Environment, China University of Geosciences , Beijing 100083, China)

 

Abstract:About 20 years of the researches on hydrogeology, environmental geology, groundwater dynamic monitoring, environmental monitoring are used to assess the environmental geology problems in the Huang-Huai-Hai plain, which have resulted from the irrational groundwater exploitation. The relevant countermeasures have been proposed for protection and control of the environmental geology problems. The assessments show that groundwater over-exploitation (maximum 363.11%) constantly is the reason that has induced the environmental-geology problems such as the regional depression cone, land subsidence, geo-fissures, land collapse, seawater intrusion, salinization and groundwater contamination in the Huang-Huai-Hai Plain. The big regional complex depression cones have been formed in the plain. There are over 20 big depression cones that have caused land subsidence, geo-fissures and land collapse. Groundwater contamination is mainly from the shallow groundwater in a form of point and linear only partial plane distribution in the plain where 29 cities are suffering from contamination such as Beijing, Langfang, Tangshan, Cangzhou, Suxian, Fuyang, Liaocheng, Dezhou and Dongying. The main excessive components are TDS、NO₃^-、NO₂^-、NH₄⁺、F、Cl^-、Fe、Mn.

Keywords: Environmental-geological problems, countermeasures, Huang-Huai-Hai Plain

 

The Huang-Huai-Hai plain includes Beijing, Tianjin, Hebei, Shandong, Henan, Anhui and Jiangsu, covering an area of 28.5×10⁴km². It is also one of the important industrial and agricultural bases but lack of the surface water resources. Groundwater resources are of importance in economic and social development in the Huang-Huai-Hai plain. With social economy development, human activities for exploitation of groundwater are aggravating day after day, while environmental geology problems relate to groundwater have severely influenced social and economic development, even life of the local people. Groundwater estimation on environmental geology problems made a significant sense to know the real situation, to protect and improve ecological environment and to advance society and economy sustainable development  in the Huang-Huai-Hai plain.

1Characteristics of the Natural Environment

The Huang-Huai-Hai Plain covers an area south of the Yanshan Mountains and east of the Taihang Mountains and north of the Dabeishan Mountains, including the Haihe and Luanhe alluvial-proluvial plain, the Huaihe plain and the panplain of the Yellow River, and goes down from west to east towards the Yellow Sea and the Bohai Sea like a dustpan. The Yellow River is taken as the boundary of Climate in this region that there is a great difference between the south and the north. The arid climate is predominant in the north part, the annual precipitation 500~600mm/a, and less than 500 mm/a in some area, the aridity 1.5~2.0; but in the south there is a warm-subhumid region, the annual precipitation 600~800mm/a, the aridity 1.0~1.5. The dense population, the industry and agriculture developing rapidly have made the water resources comparatively lack with the specific climate conditions in the region. Especially in recent years，the urbanization has made the issue even worse for the demands of water supply are increasing swiftly. Now the Huang-Huai-Hai Plain has become one of the most regions lacking water resource in China.

2 Environmental Geology Problems Induced by Unreasonable Groundwater Exploitation

In recent years, over-exploitation of groundwater is increasing day by day in order to meet the need of the economic development, by which Groundwater resources have been aggravated with occurrence of a series of environment problems, such as the regional depression cone of groundwater, land subsidence, geo-fractures, land collapse, sea water intrusion, salinization and groundwater contamination etc.

2.1 Depression cone enlarged by constant drawdown of the regional groundwater level

The depression cone is one of the most serious problems in the Huang-Huai-Hai Plain in china. The statistics show that the exploitation over 60×10⁸m³/a in 1980s to 1990s broke the equilibrium of groundwater. The shallow groundwater level went down to form 20 big depression cones (depression cone area over 100km²) even in the piedmont area where groundwater intensive exploitation as the well fields  could also form the depression cones over the mid-south of Tianjin, Tangshan, Bazhou, Baoding, Cangzhou, Shijiazhuang, Xinji, Ningjin and Xingtai in Heibei Province, Dongying and Jining in Shandong Province, Puyang and Xuchang in Henan Province, Huai’an and Binhai in Jiangsu Province (Fig.1). The situation tends to be from point to area, from the urban area to the countyside, from shallow aquifers to deep aquifers. The aquifer depletion becomes more and more serious and the environmental problems may take place as the land subsidence. The measures have been taken to control over-exploitation of groundwater since 1985 from 1985 to 1999. The result was about 2m/a recovered（as the deep groundwater depression cone at Hengshui）. The development of depression cone tends to be reduced at present.

2.2 Land subsidence

Overexploitation of groundwater, especially the concentrated well fields’ pumping, has caused the constant drawdown of the regional groundwater level accompanied with the lacunaris media compact and the land subsidence. It appears at the eastern suburb in Beijing, such as Changping, Shunyi, Fengtai, Tongzhou and Daxing etc. It is over 1800 km². The subsidence has distributed in Hebei Province such as Changzhou, Baoding, Hengshui, Renqiu, Nangong, Bazhou, Dacheng, Quzhou and Jinzhou and the central subsidence can be added up to 850mm. The subsidence averages 2.79mm/a in Xuchang in Henan Province, and about 57mmsubsidence in Puyang over 140 km² in 1997. Land subsidence 113mm in Kaifeng made the surface building destroyed. The subsidence area summed up 8798.12km², of which there is 4080.48 km² subsided over1000mm totally, some subsidence centers just located at city proper. To 1998, the subsidence center at city proper Tanggu, Hangu accumulated the most subsidence 2.81m, 3.09m and 2.84m respectively. The Huabei plain subsidence is serious made up a part of. subsidence rate reduced in evidence as a result of executive control subsidence measures by Tianjin Government. For example, exploitation reduction was from 1×10⁸m³/a in 1985 to 2435.26×10⁴m³/a  in 1998.correspondingly, and groundwater exploitation reduced form 27.4×10⁴m³/a•km² to 5.29×10⁴ m³/a•km²（Fig.2）.

Fig.2   The subsidence curve of subsidence region in Tianjin

 

 

 2.3 Geo-fractures

The geo-fractures have taken place frequently since 1980s on the alluvial fan, depression, the paleo-river course and exsisting river channel as a result of overexploitation groundwater. The fractures lasted a few meters to 500m and even longer. Some of them is over one thousand meters with the width about 2m at maximum in Handan, Yongnian, Cheng’an, Daming, Nanhe, Zhaoxian, Xinle, Zhengding, Gaocheng, Baoding, Renqiu, Suning, Bazhou, Zhuozhou, Wen’an and Gu’an town in Hebei Province. Geo-fractures in Shandong province mostly occurred in Zibo, Jining, Tai’an, Zaozhuang. They are from a few meters to hundreds of meters with the depth over 10m. Geo-fractures may bring great damages to industry, agriculture and even lives.

2.4 Land collapse

Land collapse is mainly distributed in Hebei Province such as Tangshan city proper, JingXian in Hengshui, Xushui and Zhuoxian, Zhaoxian in Baoding area, Wuji, Xinji and Luquan in Shijiazhuang area, Yongnian in Handan area, Nanhe, Qinghe and Renqiu in Xingtai. Land collapse in Xushui is of the most severity, its starting in 1974, frequently developing during 1993 and 1999. About 200 houses were cracking in EW direction. The land collapse is caused by groundwater pumping, rainstorm, groundwater infiltrating creep, water releasing media compact and etc.

2.5 Seawater intrusion

Seawater intrusion is kind of environmental geology problem along the coastal area. The seawater intrusion may cause high TDS, chloride in groundwater, water salted in the well. Groundwater then is unfit for drinking. Overexploitation of groundwater is the main reason to cause seawater intrusion. Seawater intrusion occurred in the middle of 1970s in the Huang-Huai-Hai Plain and intensified in 1980s in Zaoyuan waterhead of Qinghuangdao in Hebei Province and Shouguang-Weifang-Changyi area in Shandong Province

2.6 Soil salinization

Soil salinization is comparatively strong damage to crops. In recent years, the severe drought has increased compumtion of groundwater for agriculture and industry, thus it has caused groundwater level lowered and the waterlogging works with synthetic measures reduced salt accumulation in soil. As the result, the saline area in the Huang-Huai-Hai Plain has become smaller and the salinized area totals 30% compared in 1980s. The dominant soil salinization appears along the coastal area. In addition, it also appears at the inland wash of alluvium plain. Prevention against salinization should be executed effectively according to its cause and character combined with drought, waterlogging, alkali, salty. The reasonable and efficacious irrigation-drainage system is also important. Groundwater level should be kept lower and organic fertilizer for the farmland.

2.7 Groundwater contamination

Groundwater contamination commonly takes place in two sides of rivers, cities and the area around, mostly as point and line distribution but few as area distribution in the Huang-Huai-Hai Plain. The shallow groundwater contamination is comparatively serious. With exploitation period and amount increase, the deep groundwater is contaminated at various degrees. The main contaminants are total hardness, TDS, 3 types of nitrogen, sulfate, chloride, iron and manganese, in which the total hardness and TDS are most serious beyond standards. Contaminants mostly come form a large amount of sewage-farm, use of more fertilizer and pesticide, waste water discharge from industry. Contamination is influenced by human activities as well as hydrogeological conditions. Therefore, groundwater contamination is taken as a line from the mountainous area and the alluvial plain, the middle plain area and the coastal area from light to heavy contamination. The mountainous area and the alluvial plain belong to no or light contamination, the main contaminants nitrate, nitrite. The moderate contamination main happen in the middle part of the plain, the main contaminants total hardness, nitrite, ammonia nitrogen, TDS, pH, hydroxybenzene, sulfate. The heavy contamination is in the coastal area, the main contaminants nitrite, ammonia nitrogen, iron, manganese, fluoride and iodide.

3 Countermeasures and Advice to Groundwater Resource Protection

The Huang-Huai-Hai Plain is the most severe area at environmental geology problems in China. The social and economic sustainable development has been effected by environmental geology problems. And the overexploitation of groundwater is the direct cause, and water conservancy project, agriculture irrigation, distribution of supply well and unreasonable industrial structure are factors to effect environmental geology problems. Therefore, the measures are as follows:

1) Scientific management and programming should be strengthened on groundwater resources with combination of exploitation and recovery. The reasonable planning should be executed to control water level, irregular exploitation in order to stop ecological environment from deteriorating continuously. According to environmental capacity, the industrial structure should increase its efficiency for water utilization;

2) Watersaving and environmental law should be perfected. The solid waste cannot be dumped in the groundwater vulnerable zone and wastewater discharge should restrictedly be controlled. Pollution should be the first aim to control from pollution source;

3) Education should be enlarged on water protect. Water resources should be careful of economical use. The shallow groundwater is regarded as main exploitation layer with combination of shallow and deep, salty and fresh water mixing use. The principle should insist on the high quality water supply excellent using;

4) Research work on resources renewable, environment repairable and groundwater exploitation technology should be developed in advance and technology should be used to increase the treatment of waste water and re-use it;

5) Groundwater environment monitoring network should be improved in the municipal area and the industrial area to obtain first-hand data for protection of groundwater environment and more research work..

       

 

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