Sustainable utilization measures of groundwater resources in Beijing

Transcription

1 Sustainable utilization measures of groundwater resources in Beijing LI Yu 1*, CUI Yu 1, SUN Ying 2, LI Zhi-ping 2, WANG Xin-juan 2, WANG Li-ya 2, YANG Qing 2, WANG Rong 2 1 Beijing Geology and Mineral Resources Exploration and Development Bureau, Beijing , China. 2 Beijing, Beijing , China. Abstract: Groundwater is the main source of water supply for Beijing. Through analysis of the water resources in Beijing from 1980s up to now, this paper finds the major problems in the exploitation and utilization of groundwater in Beijing lie in the over-exploitation and pollution in groundwater, which are primarily caused by the rapid growth of population, enduring imbalance between exploitation and replenishing of groundwater and the contamination of groundwater. Thus based on this, this paper puts forward proposals and opinions to exploit groundwater in a scientific and moderate way, and to comprehensively protect the groundwater resources and environment in Beijing. Keywords: Groundwater; Environment; Sustainable development Introduction With a mere volume of water resource averages 118 m 3 (Beijing Water Authority, 2013) per capita, far lower than the internationally recognized water shortage limit of m 3, Beijing is rated as a region of serious water shortage. Simply since the founding of new China, Beijing has undergone several water crises (LIU Zhen-da, 1996) that have left profound impact on the social and economic development. During such crises, groundwater plays a vital role in supplying water for the municipality to bridge it over the crises, but long-term excessive exploitation of groundwater has charged Beijing a high price. As the limitation of water resources and the growing demand of water have become an evitable question during the urbanization process, the key of Beijing s sustainable development lies right in how to coordinate the rapid pace of urbanization and the shortage of groundwater. * LI Yu, (1971- ), Senior engineer, mainly engaged in the research and management of hydrogeololgy, engineering geology and environmental geology. dkjliyu@126.com. 1 Issues existing in exploitation and utilization of groundwater Beijing is one of the few metropolises that mainly rely on underground source for water supply in the world. Among the current multiple supplies of water for Beijing, the groundwater takes up approximately 60%, and even when river water is led to Beijing via the South-to-North Water Diversion in 2014, it still accounts for nearly 50% of the water supply. Amid the 181 water works in Beijing, 170 water works are sourced underground, i. e. 70% of the running water comes from underground. Groundwater acts such an irreplaceable role in sustaining the water supply for Beijing. Upon the South-to-North Water Diversion to Beijing, new towns in suburbs and rural areas will continue to rely on groundwater as the main source. Groundwater will still be an important component of water supply in Beijing. However, as indicated by the monitoring results, the total volume of groundwater is declining and the quality is deteriorating in Beijing. 60

2 1.1 Continued decline of groundwater level, with some shallow aquifers drained In 1960s, burial depth of shallow groundwater in plain area of Beijing is normally less than 5 m. For the past three decades, shallow groundwater has been constantly declining, by 0.3 m in 1980s, 0.5 m in 1990s and 1.2 m in 2000s. As of 2013, burial depth of groundwater in plain area of Beijing has reached the average of 24.5 m (Beijing Water Authority, 2013), with shallow aquifers in western areas such as Fengtai District basically drained. In Miyun-Huairou-Shunyi area, the exploitation by water works and of the water origin of Chaobai River in 2003, an emergency water source built up in 2008 in Huairou, has caused considerable decline of groundwater level, the burial depth up to over 40 km (Hydrogeology and Engineering Geology Team of Beijing, 2013). Storage of underground corresponding to the decline of groundwater also changes drastically (Fig. 1). In 2013, the storage of groundwater reduced by 6.5 billion m 3 compared to the same period in 1998, by billion m 3 compared to the beginning in 1980, and by billion m 3 compared to the beginning in Fig.1 Cumulative amount of loss and average depth relationship of groundwater in Beijing Groundwater is not only a precious natural resource, but also an important eco-environmental factor. The constant decline of groundwater level and annual expansion of the depression cone will result in drainage of aquifers in some areas to form underground desertification and degeneration of underground eco-system. Cutoff of rivers, shrinkage of wetlands, and exhaustion of springs and wells have become a negative image of the municipality. Among the Eight Great Sights of Yanjing, five are related to water, which has all lost their original styles. The spring of Yuquan Mountain, dubbed as the First Spring in the World by Qianlong Emperor of Qing Dynasty, has disappeared for nearly 40 years (YANG Tian-ming and FU Yan-yang, 2008). 1.2 Secondary disasters in the municipality caused by continued excessive exploitation of groundwater Beijing is sited on the alluvial-proluvial Plain of the Yongding River, its composition and structure of Quaternary sediment particles capable of sedimentation. As revealed by the study, the land subsidence and subsidence speed are closely related to the speed of decline of groundwater level and the volume of decline (Hydrogeology and Engineering Geology Team of Beijing, 2013). Constant exploitation of groundwater is the main cause of land subsidence. Areas of over 100 mm of subsidence accumulated is monitored to account for over a half of the plain area, 2.2 times larger 61

3 than that in 1999 (Hydrogeology and Engineering Geology Team of Beijing, 2013). Uneven land subsidence has caused or enlarged the ground fractures. In 1980s, ground fractures were found in Shunyi, Changping, Huairou, Pinggu and Tongzhou (Hydrogeology and Engineering Geology Team of Beijing, 2013). Such ground fractures have caused tremendous harm to the safety of productive and domestic facilities and infrastructures. At first, it damages the buildings and structures, and causes loss of the use value of land resources to some extent; secondly, it lowers the ground elevation to reduce or invalidate the anti-flood facilities and raise, tilt or even scrap the deep water pipe; and at last it affects the operation of rail transportation and increases the cost for maintenance and servicing. 1.3 Contamination of shallow groundwater, with some areas unsuitable to supply water for the municipality According to the monitoring result, around a half of the plain area monitored is found to exceed standards regarding the quality of shallow aquifer water, with the groundwater generally suffering from the 3-nitrogen pollution (Hydrogeology and Engineering Geology Team of Beijing, 2013). As the toxic, harmful and organic pollution features small in amount and diverse in categories, and the pollution mainly comes from all aspects of production and living in cities. In a word, the pollution of shallow groundwater presents a trend from city to suburb, from shallow layer to deep layer, and from inorganic pollutant to organic pollutant, which severely threatens the safety of groundwater source. At present, the quality of deep groundwater is generally good, but the excessive exploitation of the deep confined water also speeds up the land subsidence. 2 Analysis of causes 2.1 Rapid growth of population increases the rigid demand of domestic water Although the Overall Plan of Beijing ( ) stipulates the population in Beijing 62 shall be contained within 16 million by 2010 and 18 million by 2020, the permanent residents have currently reached million (Beijing Municipal Bureau of Statistics, Beijing Investigation Team, National Bureau of Statistics, 2013), far more than the planned, over 5 times more than the 4 million in 1950s (Beijing Municipal Bureau of Statistics and Beijing Investigation Team, National Bureau of Statistics, 2013) (Fig. 2). Besides, as living standards are climbing, domestic water consumption has increased by 8 times to 900 million m 3 from 100 million m 3. As the urbanization process accelerates, water demand of all regions and counties is generally rapidly growing (YU Yang-yong, 2013). In lack of surface water, groundwater has become somehow the only source for suburb towns. As Miyun, Huairou, Pinggu, Shunyi, Changping and Fangshan face not only the increased local demand, but also the task to supply water for central districts, so excessive exploitation of groundwater has become the only option. 2.2 Enduring imbalance between exploitation and replenishing of groundwater The imbalance between exploitation and replenishing of groundwater means the exploitation amount is over the replenishing amount of groundwater. Generally, groundwater is replenished around 50% by rainfall and 20% by penetration of groundwater. As the cities move forward, the replenishing conditions for groundwater are deteriorating. Hardening of ground in cities has reduced the penetration of rainfall (ZHU Lin et al. 2013). Due to water impoundment in the reservoir upstream, downstream rivers of surface waters such as Yongding River and Chaobai River have been cut off successively, with riverways resisting against penetration and water reservation and watering in fields, reducing replenishing of groundwater by 37% (Hydrogeology and Engineering Geology Team of Beijing, 2003). In 1970s, increased exploitation and reduced replenishing led to more exploitation amount than replenishing amount. At the beginning of 1980s, reduced replenishing due to years of rain shortage and increased exploitation caused an imbalance between exploitation and replenishing resulting in lowering the groundwater level and forming a

4 depression cone, the situation became worse ( Beijing, 2007; Beijing Bureau of Prospecting and Developing of Geological Mineral Resources and Beijing, 2008). Since 1999, Beijing has suffered draught for successive 13 years, with sharp reduction of replenishing of groundwater. In 2002, the impoundage of Miyun Reservoir fell below the warning line of 1.5 billion m 3 as prescribed by the water resource planning in Beijing. In 2004, it fell to as low as 646 million m 3, with the water supply security facing unprecedented challenges. Even at the face of reduction of replenishing, Beijing still supports the economic and social construction through expanded exploitation, emergency exploitation, and continual excessive exploitation, to guarantee the safety of water supply of the municipality. From 2003 up to now, the four emergency water sources-huairou, Zhangfang, Pinggu and Changping, have supplied an accumulative amount of 3 billion m 3 water. Meanwhile, there are increasingly more running water works, industrial parks, garden greening and golf courses that rely on groundwater as their source. From 2009 to 2013, the motor-pumped wells have increased by to (Beijing Water Authority, 2013). Continuous exploitation results in excessive exploitation at different levels at all districts and counties, leaving a long-term imbalance between exploitation and replenishing of groundwater. As of 2013, the area of groundwater depression cone totals km 2 (Hydrogeology and Engineering Geology Team of Beijing, 2013). Over a half of groundwater at the plain area is exploited excessively. Groundwater is at the brim of drainage in face of long-term imbalance between exploitation and replenishing. Fig. 2 Population variation of Beijing 2.3 Pollution severer than what the environment can bear has further reduced the usable groundwater Although the aquifer has a certain self-cleaning ability, pollutants that are accumulated over the capacity of the environment will threaten the quality of groundwater. Groundwater is contaminated primarily by domestic or livestockresulted wastewater, industrial wastewater, landfill, agricultural non-point source pollution, and soil pollution. The pollution source is closely related to the replenishing source of groundwater, and the pollutants are discharged into groundwater mainly by means of rainwater leaching pollutants abundant in the soil, lateral infiltration of groundwater as well as direct discharging from seepage well, seepage pit and abandoned motor-pumped well. Currently there are still 253 non-formal landfills in Beijing. The unsuitable discharge of Three Wastes by old industrial areas such as Shijingshan Industrial Park and East Suburb Chemical Industrial Park, as well as the use of seepage wells and pits left years ago, has greatly contaminated the soil and groundwater in near suburbs. Besides, many non-settled abandoned 63

5 motor-pumped wells are open louvers for groundwater, which are easily contaminated. Due to pollution, groundwater in shallow aquifers in Chaoyang, Tongzhou and Daxing is no longer suitable for drinking, which can only be used for production. To gain drinkable water, source wells are dug deeper and deeper. Deep groundwater is known to be easy in exploitation but difficult in restoration. Long-term excessive exploitation will cause secondary disasters. 3 Countermeasures for sustainable utilization of groundwater resources 3.1 Population control Rapid growth of population is demanding more water for domestic life in cities, which is a main cause for water shortage in Beijing. The domestic consumption of water accounts for 45% (Beijing Water Authority, 2013) of the total in this severely water-short city of Beijing, far higher than the average of 36.85% of other cities. Viewed from the angle of non-growth of water demand, the key for sustainable exploitation and use of water resources in Beijing lies in the containing of population. It is suggested to decide the population and scale by water so as to achieve a moderate development. 3.2 Strengthening of the groundwater management system construction The most strict water resource management system shall be implemented to strengthen the construction of management and control capacity. The guarantee and restraint of water resource to the economic and social development shall be strengthened to comprehensively perform the censorship of water impact. The Three Controls and One Protection policy is to control the exploitation of groundwater not to increase, control the quantity of motor-pumped wells not to increase, control the groundwater level not to decline, and protect the groundwater to keep at an excellent quality. The responsibilities of the local management of groundwater shall be implemented and listed into the performance examination system of the governments of districts and counties by the municipal government. During the Thirteenth 64 Five-Year Plan period, the self-supply wells replacement shall be completely finished to formulate the plan of water supply to quality of groundwater and realize an optimal use of optimal water based on the function division of groundwater. The layout of industrial structure shall be adjusted to strictly control the examination of water consumption in all industries and enterprises and resolutely eliminate the Three High industries. The allocation of water resources in Beijing shall be constantly optimized to lower the proportion of groundwater in urban water supply by 5-10%. The Censorship for groundwater resources shall be established at proper time to establish a sound system for legal enforcement and inspection for the exploitation and use of groundwater, to increase the punishment on violations such as private, unreasonable and excessive exploitation. 3.3 Strengthening of the conservation and preservation of groundwater resource (1) To reduce groundwater exploitation, take artificial injection measures, reserve groundwater and establish groundwater resources regulation system. Reduce the exploitation of groundwater at excessive exploitation area with exploitation suspension and pressure exploitation measures adopted to contain the continued decline trend of groundwater level and mitigate the ground sediment. The replacement of source for agricultural water shall be accelerated. Replace the groundwater with renewable water to greatly promote the adjustment of agricultural structure and reduce water consumption for agricultural irrigation. Establishment of facilities to use the rain and flood shall be comprehensively promoted to increase the penetration capacity of rain and flood to store and penetrate the rainwater. The availability of South-to-North Water Diversion shall be made full use of to regulate more water to replenish the debt. First replenish the water source places and emergency water source places, speed up the groundwater conservation of collective water source places, and increase the strategic storage of water resources. According to the principle of Balanced

6 Exploitation and Replenishing of groundwater, allocation of water resources shall be optimized to actively promote the joint regulation and storage of surface water and groundwater, realize a stable recovery of groundwater level and improve the water eco-environment. The layout of water source places shall be optimized and regulated to increase the strategic storage of groundwater resource and guarantee the water consumption demand at critical period. (2) To prevent first and effectively separate the pollution source of groundwater Plan for groundwater protection and pollution prevention/control actions in Beijing shall be implemented. Discharge reduction deal with source pollution of domestic wastewater, industrial wastewater, and agricultural livestock and poultry, as well as the pollution coming from informal landfills, gas stations and golf courses to promote the effective disposal of domestic wastewater and garbage discharge in rural areas, develop the green agriculture to reduce non-point source pollution, and control the ground pollution source. In the groundwater source places, scaled farms and agricultural facilities as well as industrial production and development are forbidden, existing farms, greenhouses and industrial enterprises shall be removed in plan, and green belt shall be provided in a certain range around the fault zone around the water source places. Through filling the abandoned motor-pumped wells, cutting off and guiding the pollution, constructing a clean eco-drainage basin, cutting off the spread means of pollution, and preparing and implementing the areas for use of renewable water to protect the groundwater against pollution. The groundwater monitoring network shall be further integrated and optimized to establish the monitoring system for prevention and control of groundwater pollution and guarantee the safety of water source in Beijing. 3.4 Increasing of investment in basic study on groundwater (1) Improvement of groundwater monitoring system As to the monitoring of exploitation of groundwater, the key shall be laid on the construction of the intelligent metering facility for agricultural motor-pumped wells to gradually realize the remote metering monitoring of agricultural water consumption. As to the groundwater level and quality, existing groundwater monitoring networks in Beijing shall be integrated and completed, with more networks provided for vital groundwater source places and areas already detected to be polluted to enhance the monitoring accuracy. Meanwhile, monitoring network dedicated for soil and vadose zone shall be established to gradually realize a whole-process monitoring from the pollution source, to pollution means and the aquifer. Bedrock water shall be involved in the monitoring network to gradually cover the whole city and relevant areas in Hebei, to comprehensively realize a whole-aspect, threedimensional monitoring from the plain to mountainous regions, from shallow to deep reserves, and from water amount to water level and quality, thus providing solid data basis for implementing the most strict water resource management. (2) Strengthening of basic study on groundwater, to establish a technical support system for prevention/disposal of geological issues. The groundwater exploitation and protection mechanism to ensure not only the current water consumption demand, but the long-term development especially water consumption demand in special periods, shall be explored and set up. In-depth study on the rule of replenishing and circulating of groundwater and on the rule of transfer of pollution shall be performed actively in typical areas to execute the demonstration project for restoration of groundwater pollution and research and develop feasible prevention/ treatment technologies. Scientific research on hazards of excessive exploitation of groundwater shall be performed, layered pressure exploitation scheme shall be formulated with ground sediment as the constraints, demonstration project for groundwater recharge in the sediment center area and comprehensive treatment of ground sediment shall be constructed, and the early warning mechanism targeting at various hidden troubles upon the safety of infrastructures and the eco-environment of the city shall be established. 3.5 Promotion of public participation in protection of groundwater (1) Improvement of the publicity of protection 65

7 of groundwater resources. Various media, websites and public advertisements shall be made full use of to boost the publicity of the city and water status quo and make comprehensive introduction to the public the rigid situation faced by the groundwater resources, thus truly improving all residents water saving awareness and forming a social consensus of development centred on water, and treasuring and protecting the groundwater. The publicity shall cover the basics about the groundwater; the irreplaceable role of groundwater to the city; the eco-civilization idea of balanced exploitation and replenishing to advocate the natural conservation and protection, with full use of nature-formed trenches, ponds, rivers, lakes and wetlands to firmly resist against excessive exploitation; change of groundwater between the past and present in Beijing; and the recharge planning for groundwater in Beijing. (2) Improvement of public participation mechanism and establishment of the social monitoring system. The public participation and monitoring mechanism shall be completed to practically protect the environmental benefits of the masses. The column for groundwater shall be provided at the governmental website to publicize the contact of management, monitoring and supervision departments for the groundwater, receive the feedback from the masses on groundwater, and establish the system of response at prescribed period of time. The publicity resources of the management, monitoring and supervision departments for the groundwater shall be integrated to periodically convene information issuance meeting and promote the experience in conversation and preservation of groundwater. Before the planning for water/groundwater resources of the whole city is formulated or major water-related projects especially groundwater projects are initiated, opinions from the mass shall be widely collected to reduce the impact to the groundwater by major water-related projects. References Beijing Bureau of Prospecting and Developing of Geological Mineral Resources. Hydrogeology and Engineering Geology Team of Beijing Beijing Groundwater. Beijing: China 66 Land Press. Beijing Municipal Bureau of Statistics, Beijing Investigation Team, National Bureau of Statistics of the People s Republic of China Beijing statistical yearbook. Beijing Water Authority Beijing water statistical yearbook (2013). CHEN Bei-bei, GONG Hui-li, et al Groundwater system evolution and land subsidence process in Beijing. Journal of Jilin University (Earth Science Edition), 42(1): Beijing Dynamic monitoring report of groundwater level in plain area of Beijing. Beijing Evaluation report of groundwater resource in plain area of Beijing. Beijing Monitoring report for land subsidence in Beijing. Beijing Operation report of groundwater environment monitoring network in plain area of Beijing in Beijing Evaluation on Groundwater Resource and Environmental Investigation in Beijing. Beijing Result report of investigation and assessment on sustainable use of groundwater in North China Plain (Beijing). LIU Zhen-da Review and thinking on water crises in Beijing. Beijing Water Conservancy, 6:8-9. YANG Tian-ming, FU Yan-yang Cause Analysis and disposal proposal for spring changes in Haidian District of Beijing. Groundwater, 30(5): YU Yang-yong Analysis on population change and water resources in Beijing. Labor Security World, 2: ZHU Lin, LIU Chang, et al Precipitation infiltration change in plain area of Beijing in the context of urbanization. Earth Science- Journal of China University of Geosciences, 38(5):