At present, the problems faced by water use are mainly reflected in water resources, water environment, water ecology, water disaster problems and other aspects.
2.4.1 Water resources
The water resources problem is mainly the total amount of water resources is small, the per capita possession is decreasing, the support of water resources is declining, and from the general resource water shortage to the water supply shortage, water waste and water pollution interactions to form a comprehensive structural water shortage.
Beijing-Tianjin-Hebei metropolitan area is a serious resource water shortage areas, per capita water resources possession of only 317m3, equivalent to only one-seventh of the national average; mu average water resources possession of 306m3, equivalent to only one-fifth of the national average. In order to alleviate the shortage of water resources, the utilization of foreign aid water and recycled water is increasing (Table 2.6).
Persistent drought occurs in Beijing and the surrounding areas, with a 10-year average precipitation of 476mm from 1999 to 2008, which is only 81% of the multi-year average precipitation. The average inflow of water from Miyun and Guanting Reservoirs, the main surface water sources in Beijing, was 286 million m3 and 0.88 billion m3 respectively, and the reservoir storage capacity dropped from 1.54 billion m3 and 0.42 billion m3 at the beginning of 2001 to 1.13 billion m3 and 163 million m3 at the end of 2008 respectively (Figure 2.7). The annual per capita water resources in Tianjin is 160m3, plus the inbound and outbound water transfer from Luanxuan to Tianjin, the per capita water resources possession is 370m3, which is far lower than the world's per capita possession of 1,000m3 of the water shortage warning line, belongs to the severe water shortage area, is the national average annual per capita water resources 2338m3 one-fourth of the ten, that is, than the national average average of the average amount of water per month are lower. Water shortage has become a bottleneck restricting the development of Tianjin. Hebei Province is a serious resource-based water shortage province, the average amount of water resources for many years is 20.3 billion m3, the per capita water resources is 311m3, is one-seventh of the national average, less than one-third of the internationally recognized per capita 1,000m3 water shortage standards, and even less than the Middle East and North Africa, known as the drought and water shortage. In recent years, due to the rapid development of the economy and people's living standards continue to improve, Hebei Province, water consumption has increased year by year, the annual water consumption has been as high as 22 billion m3, but the amount of water available is only 17 billion m3, the contradiction between supply and demand is very prominent. According to relevant statistics, the daily water shortage in Hebei Province cities amounted to 1.5 million to 1.7 million m3, all cities have varying degrees of water shortage. Shijiazhuang average annual water resources for 2.24 billion m3, in recent years, the city's average annual actual water consumption has reached 3.5 billion to 4 billion m3, the deficit part of the main by over-exploitation of groundwater to make up. At the same time, the contradiction between overpopulation and resource shortage is exacerbated by the low level of reuse of water resources, weak concept of water conservation and serious waste. The economic circle as long as the rivers and groundwater reduction is serious (Source: Study on Water Resources Issues in Beijing-Tianjin-Hebei Metropolitan Area Based on Circular Economy).
Figure 2.7 The process of incoming water from Miyun and Guanting Reservoirs from 1999 to 2008
2.4.2 Water Environment Problems
The water environment problems of the Beijing-Tianjin-Hebei Metropolitan Area are mainly that the water pollution is not effectively controlled and managed. In 2004, the volume of urban domestic and industrial wastewater discharged amounted to 3 billion m3, of which 1.28 billion m3 was discharged in Beijing, 560 million m3 in Tianjin, and 1.12 billion m3 in 8 cities in Hebei Province, while the centralized wastewater treatment capacity of the 10 cities in 2004 was only 4.53 million t/day, and according to the calculation of 330 days of operation per year, the volume of wastewater treated annually was only 1.49 billion m3, which was less than half of the volume of urban wastewater discharged. The annual sewage treatment volume is only 1.49 billion m3, which is less than half of the urban wastewater discharge volume, and many sewage treatment plants are not able to operate normally due to management and financial problems.
River pollution remains serious. Of the 8,200km of rivers in the Beijing-Tianjin-Hebei metropolitan area that were evaluated for water quality in 2004, only 4,000km of them met the environmental quality standards for surface water of class I-III, and about 4,200km were polluted to varying degrees, which accounted for 53% of the polluted rivers. Among them, Tianjin Jijie Canal and North Canal, Zhangjiakou Yanghe, Shijiazhuang Xiaohe and Baoding Fuhe are seriously polluted.
In the 25 large reservoirs, most of the water quality is good, but the water quality of Beijing Guanting and Chengde Miaogong two reservoirs is worse than Class III, while the water quality of other reservoirs in the reservoir area meets the Class III standard. The water quality in Baiyangdian area is generally poor, with 56% of the water surface in category IV, 22% in category V, and 22% inferior to category V (Table 2.13).
The evaluation of surface water and groundwater according to the Environmental Quality Standard for Surface Water (GB3838-2002) and the Environmental Quality Standard for Groundwater (GB/T14848-93) shows that water quality pollution in the Beijing-Tianjin-Hebei metropolitan area has been quite serious. In the surface water, the polluted river length of Luanhe River and Jidong Coast accounted for 40.5% of the evaluated river length, the north system of Haihe River accounted for 63.7%, and the south system of Haihe River accounted for 77.5%.
Since the water sources of the cities in the metropolitan area are mainly reservoirs and groundwater, the evaluation of reservoirs and groundwater quality results show that: in the current situation of the evaluation of the 15 reservoirs, most of the reservoirs water quality of Ⅲ, Miyun, Dahiting and Gangnan reservoirs water quality is better for the Ⅱ, Guanting and Yanghe reservoirs are the worst, the quality of the water for the Ⅳ. The main exceeding items are total phosphorus, permanganate index, coliform bacteria and dissolved oxygen.
Through the evaluation of shallow groundwater quality in 314 observation wells in the evaluation area of 67,261km2, there is no Class I and Class II water quality, Class III, Class IV and Class V water area of 19,372km2, 19,255km2 and 28,634km2, respectively. the main exceedance of the standard items are ammoniacal nitrogen, total hardness and nitrite nitrogen. In the evaluation area, Chengde groundwater quality is good. The evaluation results of major reservoirs and groundwater quality are shown in Table 2.13 and Table 2.14.
Table 2.13 Water Quality Condition of Reservoirs of Major Water Sources in Beijing-Tianjin-Hebei Metropolitan Area in 2004
Note: According to the Environmental Quality Standard for Surface Water (GB3838-83), which has been implemented since June 1, 2002, based on the environmental functions and protection objectives of surface water, it is classified into five categories in order of functionality:
Class II: mainly applicable to the centralized drinking water surface water source primary protection zone, rare aquatic organisms habitat, fish and shrimp spawning grounds, baiting grounds for young fish;
Class III: mainly applicable to the centralized drinking water surface water source secondary protection zone, Fish and shrimp wintering grounds, migratory corridors, aquaculture areas and other fishery waters and swimming areas;
Class Ⅳ: mainly applicable to general industrial water areas and recreational water areas not in direct contact with human beings;
Class Ⅴ: mainly applicable to agricultural water use areas and general landscaping requirements of the waters.
Table 2.14 Shallow Groundwater Quality in the Plain Area of the Beijing-Tianjin-Hebei Metropolitan Area, 2004
Source: China Water Affairs Bureau, Water Resources Special Report, 2004.
More than half of the rivers in the city do not meet the water quality standards, and some of the shallow groundwater in the plain area is polluted. Some sections of the 520km of rivers within the Sixth Ring Road are seriously polluted. The water quality of the treated rivers cannot be guaranteed due to the small amount of new water replenishment.In 2008, Beijing's annual sewage discharge of 1.320 billion m3, the total annual sewage treatment of 1.043 billion m3, sewage treatment rate of 78.9%, there are still a large number of untreated wastewater discharged into the rivers and seepage wells and seepage pits. Forty-eight percent of the city's rivers are polluted to varying degrees, and 46 percent of the river water bodies exceed the IV water quality standards, of which 45 percent exceed the V category, and most of the rivers downstream of the city are heavily polluted with ultra-V water bodies. Guanting Reservoir upstream area of a large number of waste sewage discharged into the reservoir caused the reservoir water quality exceeds the surface water environment Ⅲ standard, after 1997 has not been used as a source of urban drinking water, Miyun Reservoir in recent years, there is also a trend of eutrophication. Groundwater exceeds the Ⅲ standard accounted for 47.5%, mainly for the total hardness, turbidity and NH3-N exceeded.
If we do not consider the primary natural water quality, and only consider the water quality condition caused by secondary pollution, the monitoring wells in the metropolitan area represent an area of 72,551km2, of which the area of uncontaminated (Ⅲ water quality) accounted for 49%, mildly contaminated (Ⅳ water quality) accounted for 24%, and heavily contaminated (Ⅴ water quality) accounted for 27%, and the main pollutants are ammonia nitrogen, nitrite nitrogen, and so on. Groundwater contamination in the cities (Table 2.15).
Table 2.15 Contaminated Groundwater in Plains (Including Basins) of Municipalities Unit: km2
Source: Water Report of China Water Affairs Bureau, Beijing, 2004.
2.4.3 Water Ecology Problems
The water ecology problems in the Beijing-Tianjin-Hebei metropolitan area are mainly manifested in the three aspects of river breakups, wetland shrinkage, and over-exploitation of groundwater. The main reason is caused by the reduction of water resources and the destruction of the water environment.
2.4.3.1 River Discontinuation and Sharp Reduction of Water Intake to the Sea
In the plain section of Luan River, Steep River, Jijiang Canal, Chaobai River, North Canal, Yongding River, Baigou River, South Rejecting Horse River, Tang River, Zaolong River, Hutuo River, Busan River, Ziya River and so on, more than half of the river has been drying up, among which the section of Yongding River below Sanjiadian, the section of Jijiang Canal below Jiwangzhuang, and the section of Hutuo River below Huangbizhuang reservoir are drying up almost all the year round. In 2004 (a dry year), the amount of water entering the sea in the Luanhe, Chaobaihe, Daqinghe and Ziyahe rivers was only 1 billion m3, which was more than 95% less than the average annual amount in the 1950s. The drying up of the rivers has deprived aquatic plants and animals of the conditions for their survival, and they have lost their roles of groundwater recharge, sand transport and salt drainage, as well as the functions of river navigation and landscape. Due to the decrease in the amount of water into the sea, the main estuaries of aquatic organisms in the deterioration of the living environment, estuarine siltation intensified, the annual dredging task is heavy.
2.4.3.2 Wetland shrinkage, role decline
Baiyangdian, Qingdian Puddle, Huangzhuang Puddle, Qilihai, Dahuangbao Puddle, Tuanbo Puddle, Beidagang, Dalangdian, Nandaigang and other nine important lakes and wetlands in the plains, the area of 2,570km2 in the 1950s fell to 469km2 in 2000, a reduction of 82%. The shrinkage of wetlands has greatly reduced its function as the "kidney of the earth" to regulate the climate, store flood water, purify water bodies, provide wildlife habitat and serve as a biological gene pool.
2.4.3.3 Groundwater over-exploitation
Tangshan, Shijiazhuang, Baoding, Langfang, and other cities in the plains, where groundwater is the main source of water, have been forced to increase the exploitation of groundwater, and the shallow groundwater level is declining at a rate of 1 to 2 meters per year. The proportion of groundwater extraction has been increasing, from 67% of the total water supply in 2000 to 78% in 2004, and the groundwater level continues to fall as a result of reduced recharge from precipitation infiltration and other sources. Groundwater is over-exploited and aquifers have been depleted in some areas. For a long time, due to the persistent drought and shortage of water resources, coupled with the lack of awareness of the protection of water and ecology, the development of soil and water resources in some areas has been excessive, and the problem of competition between human beings and nature for water has been prominent, with the phenomenon of water use in the national economy crowding out the use of water in the ecological environment serious. The annual over-exploitation of groundwater in Beijing is about 580 million m3. Due to the excessive exploitation of water resources, the ecological water use of rivers, lakes and groundwater systems has been squeezed out, which has triggered a series of ecological and environmental problems, such as river outflow, shrinking lakes, degradation of wetlands, drying up of underground aquifers, and sanding of land. Beijing's groundwater resource management work, after more than a decade of efforts to achieve certain results, especially in the Beijing Municipal District, the serious over-exploitation of the situation has been controlled, but at present the vast majority of suburban counties on the development and utilization of groundwater resources is still a lack of macro-control means.
2.4.4 Water Disasters
Water-related disasters such as floods, mudslides, droughts and typhoons account for more than 80% of natural disasters. The crisis of water resources will inevitably bring a series of problems such as the deterioration of ecosystems and the destruction of biodiversity, seriously threatening the survival of human beings.
There are various types of urban water disasters, according to geographic location, there are basically five types: ① mountainside type: the city built in the alluvial fan of the mountain passes or foothills, in the rainfall is often larger due to mudslides, landslides, etc., resulting in heavy casualties. ② Along the river type: the city is close to large rivers, once the dike breaks near the city, the city will be besieged by floods. ③ Lakefront type: the city is located in the lake, when the flood season lake water level is high, the low-lying areas of the city will suffer from flooding. ④ Coastal type: the city is located on the waterfront, due to factors such as regional subsidence, often serious flooding. ⑤ Depression type: the city is built in low-lying areas or areas with drainage difficulties as well as insufficient urban drainage facilities, so that the city flooding losses are serious, and some cities are flooded with a slightly larger amount of rainfall.
Beijing-Tianjin-Hebei metropolitan area as the main urban area, the problem of water hazards first manifested itself in the hardening of urban pavements, the streets of rainwater siltation, rainwater infiltration brought about by untimely waterlogging disasters, thus affecting the normal work and life in the city. In particular, Beijing has experienced consecutive droughts in recent years that have led to sandstorms and dust storms, causing deterioration in the city's air quality. The water disasters faced by downtown Beijing are mainly the disruption of urban transportation brought by heavy rainfall and the resulting damage to road beds, while some scenic spots around Beijing face mudslides, such as Miyun, Huairou, Yanqing, Fangshan, Mentougou, and Pinggu, which are the high incidence areas of mudslides. In addition, the lack of water resources, low precipitation, urban heat island effect is serious. Tianjin urban water disasters are manifested as coastal type, mainly waterlogging disasters, while the eight urban areas in Hebei are mainly depression-type water disasters (Source: Research on water resources issues in the Beijing-Tianjin-Hebei metropolitan area based on circular economy).