Urban Water Supply

Overview

Shenzhen is located in southern China, the average annual rainfall of 1966.3mm, the average total water resources for many years 20.51 × 108m3, per capita water resources of 250m3 (2005), per capita freshwater resources per capita possession of only one-ninth of the country and one-sixth of Guangdong Province. The shortage of freshwater resources to the people of Shenzhen City, life and economic development has brought a greater impact on the municipal government to implement the policy of tilting towards water, and vigorously strengthen the construction of urban water supply projects. The total water supply capacity of the city's existing water supply projects at 97% water supply guarantee rate is 15.04×108m3, and after the implementation of the second phase of the Eastern Water Supply Project and the North Line Diversion Project, the total water supply capacity of the city's water supply projects at 97% water supply guarantee rate is 19.27×108m3, of which the water diverted from outside the country is 15.93×108m3, and that of the local and other sources is 3.34×108m3, basically meeting the needs of industrial production and people's living. It basically meets the needs of industrial production and people's life. With the development of population, economy and society, the water consumption of Shenzhen will continue to grow in the future, and it is predicted that the population of the city will reach 10.14 million in 2020, and the GDP will reach 2 trillion RMB, and the water demand is predicted to reach 26×108m3 by then.

Shenzhen's water supply source is mainly based on the diversion of water from outside the country and the main source of water locally, with a small amount of groundwater and seawater utilization. Overseas water diversion mainly relies on the Dongshen Water Supply Project and the East Water Supply Project, two major overseas water transfer projects, the water supply network trunk line and its branches, Longkou - Xikeng Water Supply Project, the North Ring Pipeline and the Shenzhen Reservoir east of the Shawan Pumping Station as the raw water transmission and distribution system to realize the Dongshen Water Diversion, the East Water Diversion and the local water sources are interlinked and reasonably deployed. Outside the water diversion and water transmission and distribution projects combined with local water storage project formed the city's water supply network system.

Shenzhen city water supply plant is a multi-center, group layout, water plant construction, water supply, water supply scale, technical conditions vary, both facilities, equipment, advanced technology, automation degree of large-scale water plant, but also facilities and equipment is simple, obsolete, backward, small and medium-sized water plant. At present, the city *** there are nearly 27 water supply enterprises, 59 water plants, the daily water supply capacity of about 590.5 × 104m3, the length of water pipeline about 1.3 × 104km, the water population of nearly 13 million people, the city's main water supply enterprises in 2006, the total water supply of 14.5 × 108m3.

Two, the status of the city's water resources

(a) hydrometeorology

Shenzhen City is a southern subtropical oceanic monsoon climate, abundant rainfall, long hours of sunshine. The average annual temperature is 225℃, the measured maximum temperature is 38.7℃, the measured minimum temperature is 0.2℃, the frost-free period is 355d, the average annual sunshine hours is 1933.8h, the average annual humidity is 76.8%. The city is located in the East Asian monsoon zone, controlled by the monsoon circulation, with a clear alternation of air currents in the winter half year and summer half year, which affects the climate change in all seasons. The ocean has a strong influence on the city's climate, making the annual and daily differences in temperature in the Shenzhen area small, with large annual rainfall, many rainy days and high atmospheric temperatures. The presence of geomorphic zones, such as the Coastal Range, allows for a large north-south difference in winter temperatures and decreasing wind speeds from south to north.

(2) Rainfall

Shenzhen's average rainfall over the years is 1,966.3 m m. The distribution of precipitation in the region is mainly affected by the Coastal Range and other geomorphic zones, showing a decreasing trend from southeast to northwest. The average rainfall over the years: above 2000 m m in the eastern region, 1700-2000 m m in the central region, and below 1700 mm in the western region.

Shenzhen precipitation is analyzed in terms of its causes, and the typhoon rainfall brought by typhoons accounts for a larger proportion of the annual precipitation. According to the statistics of 30 years from 1950 to 1979, the average typhoon rainfall for many years is 689.0mm, accounting for 36% of the average precipitation for many years. The typhoon rainfall in the largest year could reach 1648mm (1964), accounting for 69% of the precipitation in that year. Another feature of Shenzhen's precipitation is the high intensity of precipitation and heavy rainfall. The average annual rainstorms over the years account for about 40% of the annual precipitation. The intra-annual distribution of rainfall is very uneven, with the multi-year average flood season from April to September accounting for 85.3% of the annual precipitation.

Shenzhen hot climate, often windy, multi-year average rainfall, water evaporation is also large. According to many years of statistical calculations, the average evaporation for many years is 1752mm.

Surface evaporation is unevenly distributed within the year, the flood season (April to September) high temperatures, water surface evaporation, evaporation accounted for 54.8% of the year; the non-flood season (October to March) low temperatures, water surface evaporation, evaporation of small, evaporation of the whole year, 45.2%.

After analyzing, after 1980, the evaporation capacity of the reservoirs in Shenzhen City has a tendency to increase, of which after 1990, the evaporation capacity of the water surface has obviously increased by 16% compared with the decade from 1980 to 1990.

The general trend of spatial changes in evaporation is decreasing from southeast to northwest inland (Figure 2-1-8).

Figure 2-1-8 Tiegang Reservoir evaporation changes in the process line

(D) total water resources

The total water resources in a certain area is the local precipitation formed by the surface and underground water production, that is, surface runoff and underground water resources amount of the sum.

1. Surface water resources

Surface runoff in Shenzhen is mainly recharged by rainfall. According to the results of Shenzhen Comprehensive Water Resources Planning, the average annual runoff in Shenzhen is 19.18×108m3, and the annual runoff is 18.28×108m3, 13.90×108m3 and 7.70×108m3 at 50%, 75% and 97% guarantee rate, respectively.

2. Groundwater Resources

Shenzhen's underground water according to its storage According to its storage conditions, hydrophysical properties and hydraulic characteristics, groundwater in Shenzhen can be divided into three major types: loose rock pore water, bedrock fissure water and karst water. The total reserve of groundwater resources is 10.34×108m3, of which about 5.85×108m3 (i.e. variable reserve) exists in the form of runoff.

3. Total water resources

Based on the above analysis, the total amount of surface water resources in Shenzhen is 19.18×108m3, and the total amount of groundwater resources is 5.65×108m3, and after deducting the double-counting amount of 4.34×108m3, the total amount of water resources in Shenzhen is 20.5×108m3.

The city's average precipitation over the years is about 196.3mm. 1966.3mm in about 56% of the formation of river runoff, the remaining about 44% consumed in surface water bodies, vegetation, soil evapotranspiration and diving evaporation; 23% of the annual precipitation infiltration of groundwater recharge groundwater resources, the remaining part of the main consumption of diving evaporation. This is basically in line with the natural geographic characteristics of Shenzhen and precipitation, surface water, groundwater, three water transformation law.

4. River system

Shenzhen city **** there are more than 310 large and small rivers (including its tributaries), of which, the basin area of the river is greater than 10km2 of the 69 rivers, greater than 100km2 of the river 5, mainly Guanlan River, Longgang River, Pingshan River, Shenzhen River and Maocou River. Among the 310 rivers, 71 rivers are tide-sensitive. The large number of small rivers and gullies, their wide distribution and short dry streams are a feature of Shenzhen's water system.

See Table 2-1-7 for an overview of Shenzhen's major rivers

Table 2-1-7 Overview of Shenzhen's major rivers

Continued

5. Summary of current water supply

Shenzhen's water supply is mainly from the territory of the medium-sized and small-scale water storage projects and diversion of water from outside the country, the groundwater project is generally used as a part of the manufacturers of self-provided water sources.

Figure 2-1-9 Statistical map of water supply in Shenzhen in 2006

In 2006, the city's total water supply amounted to 17.31×108 m 3, of which the total amount of water diverted from abroad was 11.89×108 m 3, accounting for 68.7% of the total water supply. SAR was 5.31×108 m 3 , Bao'an District was 3.76×108 m 3 , Longgang District was 2.82×108 m 3 . the composition of water supply was 16.76×108 m 3 from surface water sources, accounting for 68.7% of the total water supply, 5,541×104 m 3 from underground water sources, accounting for 3.2% of the total water supply, and 42×104 m 3 from sewage treatment reuse, accounting for 0.02% of the total water supply. 0.02%.

Table 2-1-8 Water supply quantity of Shenzhen administrative district in 2006 is shown in Table 2-1-8, and the statistical map of water supply quantity is shown in Fig. 2-1-9.

Table 2-1-8 Water supply quantity of Shenzhen administrative district in 2006 Unit: ×104m 3

Three, current situation of water supply project

(A) Water supply pattern

At present, in terms of the pattern of water supply, Shenzhen has Formed in the SAR area, Bao'an area (including Guangming New Area) and Longgang area for the three major units of the regional water supply pattern.

The development of water sources and raw water transmission and distribution pipeline network in the SAR is relatively complete, has initially formed by the North Ring Water Transmission Pipeline to supply the eastern deep water and the water supply network from the trunk line to supply the eastern water supply system. In the maintenance period of the project outside the country, mainly by Shenzhen, Meilin, Xili and Changlingpi reservoirs to transfer water supply.

The Baoan area mainly utilizes the water supply network trunk line to introduce the eastern water, Longxi project to introduce the eastern deep water, combined with the Tiegang, Shiyan, Changliupi and other storage reservoirs to form the main water supply water source network. Among them, the central and western part of Baoan District (Baoan center cluster, western high-tech cluster and western industrial cluster) mainly rely on the Tie Shi branch line, Shisong branch line to introduce the eastern raw water, as well as Tie Gang, Shi Yan reservoir storage water supply, the eastern part of Longhua, Guanlan area (the central comprehensive cluster) through the Xikeng Reservoir to take the Longxi water supply project from the Longkou pumping station of the eastern deep water is the main.

Longgang area water source by the eastern water source, east deep water source and local water source 3 parts. Local water is relatively lack of, can only meet the streets a small amount of water, most of the raw water rely on the eastern water supply project and the east deep water supply project supply, which the eastern raw water through the water supply network trunk line, through the pingdi branch line, the cross-gang storage project, dashanpi emergency water supply project, bingkeng reservoir emergency water supply project supply; the east of the deep water rely on the Longkou pumping station and the sandy bay pumping station supply. Raw water project under construction in Dapeng Peninsula will send the eastern water to Chikao Reservoir for storage and to Kwai Chung Trail Heart Reservoir to supply Dapeng Peninsula.

(B) water supply project

Shenzhen water supply project status, mainly including water diversion projects outside the country, water transmission and distribution projects, water storage projects, as well as a small number of water lifting, groundwater and seawater utilization projects.

1. Overseas water diversion projects

Shenzhen's overseas water source comes from the Dongjiang River. Dongshen water supply project and the eastern water supply source project are the two major overseas water source backbone project in Shenzhen.

The East-Shenzhen Water Supply Project is an inter-basin large-scale water transfer project that provides raw water from the Dongjiang River to Hong Kong, Shenzhen City and the towns of Dongguan City along the project route. The project design scale of water supply is 24.23×108 m 3 / a, the design flow rate is 100 m 3 / s, its water consumption distribution: Hong Kong 11.0×108 m 3 , Shenzhen 8.73×108m3 , along the 4.0×108m3 , maneuvering surplus water 0.5×108m3.

East water supply water supply project is divided into two phases, the first phase of the project draws 3.5 ×108 m 3 / a, the first phase of the project drawdown of 3.5 The eastern water supply source project is divided into two phases, the first phase of the project draws 3.5×108 m 3 / a, the design flow rate of 15 m 3 / s. At present, the construction of the second phase of the eastern water source project, the project draws 3.7×108m3 / a, the design flow rate of 15m3 / s. After the completion of the two phases of the project, the eastern water supply source project can divert water of 7.2×108m3 / a.

2. Transmission and distribution projects

In order to achieve the water diversion from outside the country and the local reservoirs joint dispatch, Shenzhen has built a water supply project. Dispatch, Shenzhen City, built the water supply network trunk line, the North Ring Water Transmission Trunk Pipeline and the North Line Diversion Project and other water transmission projects, through the Tie Shi Branch Line, Shisong Branch Line, Pingdi Branch Line, Henggang Storage Project, Longkou - Xikeng Water Supply Project and other branch line projects, connecting Shenzhen, Xili, Songzikeng, Qinglinyuan, Tiegang, Shiyan and other storage reservoirs, the raw water from the Dongjiang River will be transported to the city's various districts to form a dual source of water in the eastern water and the East Deep Water Water supply guarantee system. At present, the city has built and under construction at all levels of supporting auxiliary water branch line 15, with a total length of 213.7km.

3. Water storage project

As of 2006, the city *** there are 173 water storage reservoirs, of which the water supply reservoirs have 124, including 10 medium-sized reservoirs, small (1) 62 reservoirs, small (2) 52 reservoirs, the water supply reservoirs in the 50 percent, 75% and 97% of the guaranteed rate of water supply in the case of 4.04 × 108m3, 3.31 × 108m3 and 2.69 × 108m3.

4. Other water supply projects

Shenzhen City is currently built in a larger river water project there are two, respectively, located in the Maochew River and Guanlan River. Maozhou River water lifting capacity of 5 m 3 / s, Guanlan River water lifting project water lifting capacity of 6 m 3 / s. The city also has a small amount of groundwater mining projects each year, the annual extraction of about 0.55 × 108 m 3, of which 0.23 × 108m3 of shallow groundwater, deep groundwater 0.32 × 108m3. Shenzhen City, a region with rich seawater resources, the city currently has no desalination projects, seawater is basically used for industrial cooling of power companies. Seawater is basically used for industrial cooling water for electric power enterprises, and the amount of seawater directly utilized in Shenzhen in 2006 was 72.9×108m3.

Four, urban water supply project planning and implementation

(A) water planning pattern

In order to ensure that Shenzhen's water supply security, the city's planning for the construction of new reservoirs and expansion of reservoirs, construction of reserve water supply projects, and non-traditional water resources utilization, Improvement of water supply network construction and supporting water plant construction.

Through the rational allocation of water resources, Shenzhen city water supply in the future will form the overall layout of the Dongjiang River runoff, local reservoirs and seawater as the "source", to the eastern water supply water supply project, Dongshen water supply project and water supply network trunk line, the northern diversion project and other water transmission projects as "line ", Shenzhen, Tiegang, Gongming, Songzikeng, Qinglin Trail and Gulf reservoirs as the "storage center", water purification plant as the "point" of the cross-basin, cross-regional diversion, storage, lifting, supply and use of coordinated urban water supply Water resources development and utilization system.

(2) water construction

1) the construction of offshore water supply project: the completion of the second phase of the eastern water supply project.

2) water storage project construction: the new Dongchong Reservoir, Dongzi Reservoir, Pilot Reservoir *** 3 sits of reservoirs; expansion of the Tiegang Reservoir, Tongluo Trail Reservoir, Changling Pi Reservoir, Songzikeng Reservoir, Goose Neck Reservoir, Pilot Reservoir, Kankang Reservoir, Tiekeng Reservoir and Damali Reservoir 9 reservoirs. The new water supply under 97% guarantee rate of new and expanded reservoirs is 1960×104m3, increasing the storage capacity by 1.20×108m3.

3) Reserve water source construction: completion of the Qinglin Trail Diversion and Storage Project, Gongming Water Supply Storage Project, and Bay Reservoir Project, increasing the storage capacity by 4.0×108m3.

4) Water supply network construction: completion of the North Line Diversion Project (120×104m3/d), Dapeng Peninsula branch water supply project (Shahu - Kwai Chung section) (40×104m3/d), Dapeng Peninsula water source project - Damguang branch project (30×104m3/d), Yantian branch water supply project (18×104m3/d), the big industrial city branch water supply project (55×104m3/d) 6 zones of sub-division of the water supply Water transmission and distribution project construction.

5) non-traditional water resources development and utilization of construction: the implementation of the Olympic Sports Center rainwater utilization project, Longhua second line of the expansion of rainwater utilization project, Shenzhen Qiaoxiangcun Affordable Housing Residential Area, Longgang Senior Technical School rainwater utilization project and Lianhuashan Park rainwater utilization project; to carry out the Nanshan Shekou (2.7 × 104t / d), Fuhuade Power Plant (0.2 × 104t / d) ) desalination and Yantian, Nanshan, Dapeng Peninsula area seawater direct use of pilot project construction; construction of Nanshan, Futian, Binhe, Luofang, Xili, Caopu and other sewage treatment plants as the main sewage reuse project area, to carry out Shekou, People's Mansion, Bank of China District, Whale Hill Villa, Yuezhong District, Jade Park District and Fuhua Building, such as the pilot project of water reuse construction.

New Nanshan Water Plant, Hongmushan Water Plant, Guangming Water Plant, Zhu Au Water Plant (Phase IV), Phoenix Water Plant, Shiyan Water Plant, Otter Lakes Water Plant, Big Industry City Water Plant, and other major water plants; expanding the Shekou Dongbin Water Plant, Penjieshan Water Plant, Yantian Water Plant, Koshihtang Water Plant, Wufengrake Water Plant, Guanlan Xiqian Water Plant, He'au Water Plant, Nankang Water Plant, Miaokeng Water Plant Goosegongling Water Treatment Plant, Pingdi Water Treatment Plant and Center City Water Treatment Plant and other major water treatment plants. Newly built and expanded water plant with a new scale of 246 × 104m3 / d.

V. Environmental Impact Assessment

(A) water supply water source water environment status quo

1. Water supply reservoirs

According to the status quo survey, the main water supply reservoirs in Shenzhen City, the overall quality of the water in a good condition, the vast majority of reservoirs for the Ⅱ type of water quality, the Shenzhen Reservoir, the Tiegang Reservoir, the Chikao Reservoir in the individual water period have reached Ⅰ type of water quality, the Shenzhen Reservoir, the Tiegang Reservoir, the Chikao Reservoir. Shenzhen Reservoir, Tiegang Reservoir, Chikao Reservoir, have all reached the water quality standard of Class I during the individual water period, and the water quality condition has further improved. Shenzhen has been delineated water source protection area of 28 reservoirs, only 7 reservoirs water quality exceeds the standard, of which 5 are not set up routine monitoring section of the reservoir, the remaining 2 are located in Shiyan Reservoir and Luotian Reservoir, the main exceedance of COD and permanganate, exceeding the standard is mainly due to the tributaries into the reservoir of the COD contribution rate is larger, measures should be taken to further control the pollution load of the tributaries into the reservoir. The nutrient status of drinking water sources in Shenzhen is generally good, only individual reservoirs have mild eutrophication, and the number of these reservoirs only accounts for 7% of the number of evaluated reservoirs.

Summary of water quality evaluation results of major reservoirs in Shenzhen in 2005 is shown in Table 2-1-9.

2. Lifting rivers

According to the results of the latest river survey, the city has different degrees of pollution in both large and small rivers due to the discharges of industrial and domestic sewage as well as the mixing of rainwater and sewage. Large and small rivers are polluted to varying degrees, the vast majority of which do not meet the water function, water quality requirements. As the source of water supply in Shenzhen City, Maozhou River and Guanlan River water environment quality deteriorates year by year, the water pollution problem is particularly prominent.

Table 2-1-9 Summary of water quality evaluation results of major reservoirs in Shenzhen in 2005

1) Maozhou River: the annual average values of dissolved oxygen, permanganate index, biochemical oxygen demand, non-ionic ammonia, volatile phenols, petroleum and total phosphorus in the upper reaches of Maozhou River exceeded the standard of Class III, and the monitoring values of suspended solids, nitrite nitrogen, total mercury, total cadmium and hexavalent chromium exceeded the standard, and the quality of water was worse than Class V. The water quality in the lower reaches of Maosou River was worse than Class V, but the water quality in the lower reaches of the river was worse than Class V. Downstream of Maozhou River, suspended solids, dissolved oxygen, permanganate index, biochemical oxygen demand, total cadmium, petroleum and total phosphorus exceeded the annual average value of total hardness and non-ionic ammonia monitoring value also exceeded the standard, water quality worse than V.

2) Guanlan River: the annual average values of dissolved oxygen, permanganate index, biochemical oxygen demand, non-ionic ammonia, volatile phenols, petroleum and total phosphorus in Guanlan River exceeded the standard of Class III, and the monitoring values of suspended solids, nitrite nitrogen, total mercury, total cadmium and hexavalent chromium also exceeded the standard, and the water quality category is inferior to Class V.

Shenzhen's lack of local water resources, the deterioration of the water environment of the existing water supply sources, not only seriously affect the quality of urban landscape and habitat, but also further aggravate the shortage of water resources.

(2) Water Environment Protection Planning

1. Planning Objectives

To curb the imbalance trend of local water ecosystems of water supply sources and to promote its benign cycle by adopting various water ecosystem protection or restoration measures such as the construction of water culverts and forests. Ensure that the water quality of urban drinking water sources in reservoirs meets the standard from 98% to 100%. The average forest land cover in the water source protection area reaches more than 65%, and the degree of forest closure reaches more than 95%.

2. Main Measures

1) Pollution Source Control: Pollution source control includes the control of point source and surface source of polluted water. Point source pollution control to intercept sewage outfalls, sewage treatment and drainage system construction as the focus. Surface pollution control mainly includes ① source control; ② lakeshore greening combined with natural wetlands to control surface pollution around the lake; ③ end treatment.

2) Artificial wetland: artificial wetland system is the use of wetlands to purify sewage capacity of man-made construction of ecological engineering measures, this measure is the stone, sand, soil and other materials according to a certain proportion of the composition of the substrate, and planted after the selection of aquatic, wet plants, composed of engineered wetland system similar to the state of the natural wetland. Artificial wetland is divided into floating plant system, aquatic plant system and submerged plant system. Through the purification effect of substrate, plants and microorganisms, it has high removal rate of TN, TP, COD, BOD and heavy metals, etc. It can obtain the best ecological, economic and social benefits of sewage treatment and resource utilization, and it is one of the important engineering measures for controlling surface source pollution.

3) front reservoir: the original watershed and reservoirs are divided into the main reservoir, front reservoir and upstream of the watershed area. The former reservoir can be regarded as a sewage treatment system, which is the upstream sewage is incorporated into the former reservoir before entering into the reservoir, and then discharged into the main reservoir after the water becomes clear through sedimentation and absorption by plants. The pre-positioned reservoir purifies the flowing water that originally went directly into the main reservoir, which can reduce the pollutants in the source water of the main reservoir, and at the same time can reduce the amount of sediment entering the reservoir. The former reservoir technology is one of the effective ways to prevent and control surface source pollution in the water source protection area of the reservoir because of its lower cost, can benefit from multiple parties, suitable for a variety of conditions and other advantages.

4) Restoration of the reservoir waterfront zone: through the implementation of artificial wetlands, ecological gravel and vegetation restoration and other ecological projects in the reservoir waterfront, poor hydraulic flow conditions and heavy pollution in the area of water disposal and purification, adsorption and transfer of pollutants and nutrients from the surface source, improve water quality, interception of fixed particulate matter, reduce the particulate matter in the water column and sediments, while providing habitat for the biological reproduction and growth, to achieve the ecological restoration of the reservoir waterfront zone. Ecological restoration.

5) Water source protection forest: water source protection forest construction can improve the structure of the forest phase, increase woodland coverage, improve the water conservation capacity, effective control and mitigation of surface pollution. Due to the filtering, absorbing and shading effects of forests, when precipitation and runoff pass through the filtering and retention effects of the forest canopy, deadfall layer and soil layer of forests, the types and concentration of harmful compounds in water can be greatly reduced; and due to the characteristics of the water body, such as low water temperature and mobility, and thus the water quality is pure, rich in dissolved oxygen, and with fewer pathogens.

6) Reservoir water body restoration technology: through the controllable artificial stream ecosystem, adjusting the conditions of water flow, light intensity and substrate, etc., exerting the characteristics of rapid growth and reproduction of the living algae, removing excess nutrients from the water body, improving water quality and increasing dissolved oxygen. At the same time, combined with the water grass restoration and landscape construction and other projects, the use of food web theory and biological manipulation technology, in line with the surface water Ⅲ standards of the lake to adjust the fishery structure, focusing on the proliferation of indigenous fish, the development of ecological fisheries without environmental pollution, the construction of fish ornamental areas and angling areas; inferior to the surface water Ⅲ standards of the lake, to consider fish algae control measures, focusing on the construction of fish algal control areas.

7) water source protection area isolation project: isolation project is mainly in the first level of water source protection area boundary set boundary pillars, build fence, the implementation of semi-enclosed management, removal of seedlings, flower farms, replanting of water culverts, lychee, and other fruit forests in the first phase of the natural growth, and gradually transformed into water culverts. The implementation of the reservoir primary water source protection zone isolation project can effectively block outsiders from entering the protection zone, roadside crash barriers, interceptor pools (constructed in other projects), etc. can effectively reduce the risk of hazardous transport goods dumped into the reservoir, improve the safety and security of the water quality of the reservoir.

Six, problems and recommendations

(a) Problems

1) The contradiction between water supply and demand still exists. According to the prediction of Shenzhen City in 2020, urban water demand will reach 26 × 108m3, can be determined by the water supply of 19.27 × 108m3, water supply gap of 6.7 × 108m3, this part of the gap in the planning and utilization of non-traditional water resources development and increase the diversion of water to make up for the outside world. However, the development and utilization of non-traditional water resources is a long-term and gradual process, to meet the water in the long term there is still a certain gap.

2) non-traditional water resources utilization is still in its infancy. From the water supply source, the development and utilization of water resources in Shenzhen City is mostly limited to traditional water resources, vigorously develop and utilize rainwater, seawater, sewage (in) water and other unconventional water resources, is the establishment of a resource-saving society requirements, but also to solve the shortage of water resources in Shenzhen City, one of the ways. Shenzhen City has a rich amount of unconventional water resources, has a certain potential for development and utilization, but due to the lack of scientific planning guidelines and other practical difficulties, whether it is the reuse of sewage treatment, seawater utilization or rainwater utilization is only in the initial stage.

3) the lack of multiple water sources optimization and deployment system. Shenzhen City, many water sources, transmission and distribution network is complex, the existing water deployment is mainly a single water source project demand deployment. In the future, with the development of non-traditional water sources, water supply network is gradually built and improved, a variety of water sources need to be implemented between the joint scheduling to ensure that the water works to maximize their respective functions, to achieve the best economic benefits.

(B) Recommendations

1) To carry out research related to the solution of the long-term water demand gap. Because of the long-term water demand in Shenzhen City, there is still a certain gap, just rely on increasing the use of non-traditional water resources to solve the existence of many aspects of uncertainty is not enough. In order to ensure the security of urban water supply, Shenzhen should strengthen the water cooperation with neighboring cities, carry out research on increasing water diversion from abroad from the perspective of optimal allocation of river basin and regional water resources, and economically and rationally put forward measures to solve the gap in the long-term water demand of Shenzhen.

2) Establishment of water supply source optimization scheduling system. In order to make full and reasonable use of limited water resources, the need to establish to take, transmission, distribution of water subsystems composed of optimal scheduling system, to maximize the reliability of the project water supply and economy.

3) Strengthen the water supply pipe network connection of each cluster. SAR outside the water supply is mainly street as a unit, the lack of connection between each other, is not conducive to increasing the complementary nature of water supply and improve the security of water supply. It is recommended to increase the water supply network links between the groups, so that the water supply between the groups and even between the districts can be adjusted to improve the water supply of the city's water supply guarantee rate.

4) Further increase the development and utilization of non-traditional water resources. Due to the lack of local water resources in Shenzhen, long-term reliance on water diversion from abroad has a certain degree of insecurity, but also does not accord with the development of the circular economy of the overall idea, the future should focus on strengthening the development and utilization of non-traditional water resources. At the same time, the government should formulate relevant laws and regulations for the development and utilization of non-traditional water resources to give certain preferential measures, so that the development and utilization of non-traditional water resources with economic power and policy protection.