A method for constructing a sustainable water resource utilization system for coastal cities and its application

Abstract

The present invention discloses a method for constructing a system for sustainable utilization of water resources in coastal cities and its application. The method constructs a system for sustainable utilization of water resources in coastal cities with the goal of balancing the supply and demand of water resources and the coordinated development of economy, society and environment through key control variables. According to the supply and demand of water resources and the type of development and utilization in coastal cities, the system is first divided into a water supply system and a water demand system. Then, the key control variables of the system for sustainable utilization of water resources in coastal cities are determined, and the dynamic changes of the structure, efficiency and other aspects of the sustainable utilization of water resources in coastal cities are simulated by adjusting the key control variables. Finally, according to the adjusted key control variables, the balance of supply and demand of water resources in coastal cities is achieved, and the goals of sustainable utilization of water resources and the coordinated development of society, economy and ecological environment are met. The present invention proposes for the first time a method for constructing an "economic-social-ecological" system for sustainable utilization of water resources in coastal cities, which is scientific, effective and easy to promote and use.

Description

Technical Field

[0001] The invention belongs to the technical field of sustainable utilization of water resources, and in particular, is a systematic method for planning and implementing sustainable development and utilization of water resources in coastal cities. Background Art

[0002] Water resources are irreplaceable natural resources for human survival and development, the material basis for achieving sustainable development of the economy, society and ecological environment, a strategic economic resource, an organic part of the comprehensive national strength, and a key controlling factor in the coordinated development of population, economy, society, resources, environment, ecology and other factors.

[0003] Due to the particularity of my country's economic and social development, water resources issues have become a key factor restricting the sustainable development of the economy, society and ecosystems of many coastal cities in my country. It also determines the necessity for cities in my country to implement a sustainable development strategy based on the sustainable development of water resources to support the entire economy, society and ecological environment.

[0004] The economy of coastal cities is relatively developed, and with the continuous development of the economy and the improvement of people's living standards, the demand for water resources is increasing, and the contradiction between water supply and demand is becoming more acute. Therefore, there is a greater need for relevant methods or models for the sustainable use of water resources. At present, this field urgently needs a method for constructing a sustainable use system for water resources in coastal cities. Summary of the invention

[0005] Aiming at the problem that water shortage in coastal cities restricts the sustainable development of urban economy, society and ecological environment, the present invention proposes a method for constructing a system for sustainable utilization of water resources in coastal cities. Through the key variable control method, a sustainable utilization system for water resources in coastal cities with the balance of water resource supply and demand as the main goal is established, so as to realize the sustainable utilization of water resources in the process of urbanization development and achieve the purpose of coordinated development of urban economy, society and ecological environment. The method is objective and has universal applicability.

[0006] The present invention provides a method for constructing a sustainable utilization system of water resources in a coastal city, and the method is based on a key control variable method; the method is:

[0007] First, according to the supply and demand of water resources and the types of development and utilization in coastal cities, the system is divided into a water supply system and a water demand system. The water supply system includes four subsystems: surface water supply system, groundwater supply system, recycled water supply system, and seawater desalination supply system; the water demand system includes four subsystems: agricultural water system, industrial water system, domestic water system, and urban environmental water system.

[0008] Then, a sustainable utilization system of water resources in coastal cities is constructed, and the key control variables in the system are determined; the dynamic changes of the structure and efficiency of sustainable utilization of water resources in coastal cities are simulated by adjusting the key control variables;

[0009] Finally, based on the adjusted key control variables, calculate whether the difference between supply and demand of water resources in coastal cities meets the supply-demand balance relationship; so that the adjusted key control variables can meet the goals of sustainable utilization of water resources in coastal cities and coordinated development of society, economy and ecological environment.

[0010] Specifically, the steps are as follows:

[0011] (1) Classify water resources according to the supply and demand of water resources and the types of development and utilization in coastal cities; divide the sustainable utilization system of urban water resources into four water supply subsystems, namely, surface water supply system, groundwater supply system, recycled water supply system, and seawater desalination supply system, and four water demand subsystems, namely, agricultural water demand system, industrial water demand system, domestic water demand system, and urban ecological environment water demand system. The surface water supply is further divided into three types, namely, urban water storage, urban water diversion, and urban water extraction. The water supply system and water demand system need to include all water resources in the city;

[0012] The mathematical expression of coastal city water resources classification can be summarized as follows:

[0013] W 城市可供水量 =W 地表水供水量 +W 地下水供水量 +W 再生水供水量 +W 淡化水供水量

[0014] W 地表水供水量 =W 蓄水量 +W 引水量 +W 提水量

[0015] W 城市总需水量 =W 生活需水量 +W 工业需水量 +W 农业需水量 +W 生态环境需水量 ;

[0016] (2) Construct an “economic-social-ecological” system for the sustainable use of water resources in coastal cities and determine the key control variables of the system; follow the principles of scientificity, integrity and feasibility, and select variables that are located at the starting point of the system and play a key role as the key control variables of the system;

[0017] (3) Simulate the dynamics of urban water resource utilization by adjusting key control variables; implement various water-saving measures without limiting economic growth and increasing the urbanization rate;

[0018] (4) Based on the adjusted key control variables, calculate whether the difference between urban water supply and demand meets the supply-demand balance relationship, and check whether it meets the development requirements of sustainable utilization of water resources in coastal cities and whether it meets the requirements of coordinated development of coastal cities' economy, society, resources and environment; if not, readjust the key control variables until they meet the requirements.

[0019] The key control variables selected in step (2) must be located at the starting point of the system and must be variables that have a key impact on the sustainable use of urban water resources: industrial output value increase rate, water consumption per 10,000 yuan of industrial output value, urbanization rate, population growth rate, green space and road water quota, urban domestic water quota, rural domestic water quota, agricultural irrigation water quota, sewage treatment rate, sewage reuse rate, desalination water capacity, diverted water supply, and stored water supply.

[0020] In the step (3), firstly, various water-saving measures and technologies are considered to be implemented to achieve the purpose of reducing the urban and rural domestic water quota, the water consumption per 10,000 yuan of industrial output value, the green road water quota, the farmland irrigation water quota, etc.; secondly, the growth rate of the city's economic development and urbanization level is not restricted; at the same time, the efforts of urban sewage treatment and rainwater collection are increased, the sewage recycling rate is improved, the seawater desalination technology and industry are developed, and the water diversion and storage projects are scientifically constructed to enhance the city's water supply capacity in general.

[0021] In the step (4), the specific measures for adjusting the key control variables need to be combined with the actual development and utilization of water resources in coastal cities and the planning and development requirements, and follow the principles of scientificity, integrity and feasibility.

[0022] The "economic-social-ecological" system for sustainable utilization of water resources in coastal cities constructed by the construction method based on the key control variable method in the present invention is a complex system, which is a social and economic ecological system for sustainable utilization of water resources composed of the coupling of water resources with population, economy, and ecological environment.

[0023] The present invention can be applied to the planning and design of sustainable utilization of water resources in coastal cities, including:

[0024] (1) To provide methodological and theoretical guidance for the water resources departments of coastal cities to carry out the planning and design of projects related to the sustainable utilization of water resources.

[0025] (2) Provide theoretical and practical references for solving various problems in the sustainable utilization of water resources in coastal cities. The method of the present invention is used to evaluate the sustainable utilization of water resources in coastal cities and identify the main factors affecting the sustainable utilization of local water resources, thereby providing a basis for policy formulation.

[0026] (3) By using the method of the present invention, a water resource efficient utilization system is constructed to determine the priorities of various water resources, provide guidance for further formulating virtual water strategic planning and what measures should be taken to ensure a good trend in the sustainable development of water resources, and provide reference for other water-scarce cities to formulate a sustainable water resource utilization system.

[0027] Compared with the prior art, the advantages and positive effects of the present invention are:

[0028] 1. This invention proposes for the first time a method for constructing an "economic-social-ecological" system for sustainable utilization of water resources in coastal cities;

[0029] 2. The present invention integrates the key factors affecting the sustainable utilization of water resources in coastal cities into 13 controllable key control variables, which has wide applicability and ensures the scientificity and effectiveness of coastal cities in adopting this system method to carry out system research, engineering design planning, etc.;

[0030] 3. Compared with other methods, the present invention can analyze and evaluate the sustainable utilization of water resources in coastal cities in a simpler and more intuitive way, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of the construction method of the coastal city water resources sustainable utilization system of the present invention.

[0032] Figure 2 This is the sustainable utilization system of coastal city water resources and the distribution of key control variables of the present invention.

[0033] Figure 3 This is the system flow chart of Qingdao water resources carrying capacity SD model in Example 2.

[0034] Figure 4 The changing trends of water resources supply and demand in Qingdao under the four scenarios of Example 2 are shown.

[0035] Figures 5 to 11 They are respectively the changing trends of economic indicators, available water resources system-related indicators, agricultural water system-related indicators, industrial water system-related indicators, domestic water system-related indicators, urban environmental water system-related indicators, and sewage treatment and reuse system-related indicators in Qingdao during the period 2011-2030 in Example 2.

[0036] Fig.12 This is the order of water resource utilization in the generalized scheme of water resource allocation in Qingdao in Example 3. In the figure, the solid line represents the main form of water resource utilization in Qingdao at present, and the dotted line represents the water resource utilization subject to certain conditions and limits. DETAILED DESCRIPTION

[0037] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. After reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, the technical solutions of the present invention, and its features, advantages, etc. will become clearer.

[0038] Embodiment 1, as Figure 1 , Figure 2 As shown, the method for constructing a system for sustainable utilization of water resources in coastal cities in this embodiment specifically includes the following processes:

[0039] S101. Classify water resources in coastal cities according to their supply, demand and development and utilization types;

[0040] According to the supply and demand of water resources and the types of development and utilization, the sustainable utilization system of urban water resources is divided into four water supply subsystems, namely the surface water supply system, the groundwater supply system, the recycled water supply system, and the seawater desalination supply system, and four water demand subsystems, namely the agricultural water system, the industrial water system, the domestic water system, and the urban environmental water system. The surface water supply is further divided into three types: urban water storage, urban water diversion, and urban water extraction; the water supply system and water demand system need to include all water resources in the city;

[0041] The mathematical expression of coastal city water resources classification can be summarized as follows:

[0042] W 城市可供水量 =W 地表水供水量 +W 地下水供水量 +W 再生水供水量 +W 淡化水供水量

[0043] W 地表水供水量 =W 蓄水量 +W 引水量 +W 提水量

[0044] W 城市总需水量 =W 生活需水量 +W 工业需水量 +W 农业需水量 +W 生态环境需水量 ;

[0045] S102. Construct an “economic-social-ecological” system for sustainable use of water resources in coastal cities and determine the key control variables of the system;

[0046] Following the principles of scientificity, integrity and feasibility, variables that are located at the starting point of the system and have a key influence are selected as the key control variables of the system. Finally, 13 variables including industrial output value increase rate, water consumption per 10,000 yuan of industrial output value, urbanization rate, population growth rate, green road water quota, urban domestic water quota, rural domestic water quota, agricultural irrigation water quota, sewage treatment rate, sewage reuse rate, desalination water capacity, diversion water supply, and storage water supply are determined as the key variables of the system. The specific distribution of the constructed coastal city water resources sustainable utilization system and the selected key control variables in the system is shown in Figure 2.

[0047] S103, simulate the dynamics of urban water resource utilization by adjusting key control variables;

[0048] When adjusting key variables, we must meet the requirements of sustainable use of urban water resources and take into account the coordinated development of urban population, resources, environment and economy. Therefore, we must first consider implementing various water-saving measures and technologies to achieve the purpose of reducing urban and rural domestic water quotas, water consumption per 10,000 yuan of industrial output value, green road water quotas, and farmland irrigation water quotas; secondly, we must not limit the growth rate of urban economic development and urbanization levels; at the same time, we must increase the intensity of urban sewage treatment and rainwater collection, improve the sewage recycling rate, develop seawater desalination technology and industry, and scientifically construct water diversion and storage projects to enhance the city's water supply capacity as a whole.

[0049] S104. Based on the adjusted key control variables, calculate whether the difference between urban water resources supply and demand meets the supply and demand balance relationship, and verify whether it meets the goals of sustainable development of water resources;

[0050] According to the adjusted key control variables, calculate whether the difference between urban water supply and demand meets the supply and demand balance relationship, and check whether it meets the requirements of sustainable development of water resources in coastal cities and the requirements of coordinated development of coastal cities' economy, society, resources and environment. If not, readjust the key control variables until the requirements are met.

[0051] Example 2: Taking Qingdao as an example, the method for constructing a sustainable water resource utilization system for a coastal city is specifically described.

[0052] 1. Constructing a sustainable water resource utilization system based on the SD model of water resource carrying capacity

[0053] Qingdao has a relatively developed economy. With the continuous development of the economy and the improvement of people's living standards, the demand for water is increasing, the requirements for water quality are getting higher and higher, the contradiction between water supply and demand is becoming more acute, and the total amount of local surface water and groundwater has no greater development potential. Therefore, it is necessary to coordinate the planning of urban and rural water use, rationally develop, optimize the setting and efficiently utilize various water resources such as sewage, rainwater, seawater and guest water; make decisions based on the coordination of resources, environment and society, and fully demonstrate the technical feasibility and economic rationality; build a sustainable water resource system with water resource carrying capacity as the core, among which the water resource carrying capacity is aimed at balancing the supply and demand of water resources in Qingdao.

[0054] This study adopts the system dynamics (SD) method, with the help of VensimPLE software modeling, and through the simulation of various different schemes, studies and analyzes the dynamic relationship between water resources and population, environment and economic development in Qingdao.

[0055] 1. Classify water resources according to their supply, demand and development and utilization types in Qingdao, and establish a SD model.

[0056] The SD model is used to simulate the dynamic changes of Qingdao's water resources carrying capacity from 2011 to 2030 under different scenarios. In this study, the spatial boundary of the SD model of Qingdao's water resources carrying capacity is the entire Qingdao City, the simulation time period is 2011-2030, 2011 is taken as the base year, and the simulation step length is 1 year.

[0057] According to the supply and demand of water resources and the types of development and utilization, the sustainable utilization system of urban water resources is divided into four water supply subsystems, namely, surface water supply system, groundwater supply system, recycled water supply system, and seawater desalination supply system, and four water demand subsystems, namely, agricultural water demand system, industrial water demand system, domestic water demand system, and urban ecological environment water demand system. The surface water supply is further divided into three types: urban water storage, urban water diversion, and urban water extraction. The subsystems interact and are interconnected, and the mathematical expression after water resource classification can be summarized as follows:

[0058] W 城市可供水量 =W 地表水供水量 +W 地下水供水量 +W 再生水供水量 +W 淡化水供水量

[0059] W 地表水供水量 =W 蓄水量 +W 引水量 +W 提水量

[0060] W 城市总需水量 =W 生活需水量 +W 工业需水量 +W 农业需水量+W 生态环境需水量

[0061] This study used the SD professional modeling software Vensim-PLE to establish the system flow diagram of the SD model of Qingdao’s water resources carrying capacity (Figure 3).

[0062] With reference to Qingdao Statistical Yearbook 2012, Qingdao Water Resources Bulletin 2011 and relevant planning data, the initial values ​​of the main variables in the equation are determined, see Table 2.1.

[0063] Table 2.1 Initial values ​​of main variables in Qingdao's water resources carrying capacity SD model

[0064]

[0065] 2. SD model test

[0066] Input the parameters into the model for simulation operation, and compare the results with the historical actual data to verify the consistency and make a judgment on the reliability and accuracy of the model simulation. Due to the large number of model variables, this study mainly conducts historical verification on the total population and domestic water demand (see Table 2.2). Through analysis, it can be seen that the simulated values ​​of the two variables are basically consistent with the actual values, and the error is within 6%. It can be seen that the predicted value is relatively accurate and the model is effective.

[0067] Table 2.2 Model historical value test results

[0068]

[0069] 3. Scheme design and simulation results analysis.

[0070] According to the actual situation and future development direction of Qingdao City, decision variables are selected, various plans are designed, and simulations are carried out to analyze the changing trends of water resources carrying capacity that may be caused by various plans.

[0071] Following the principles of scientificity, integrity and feasibility, 13 variables that play a key role at the starting point of the flowchart (industrial output value increase rate, water consumption per 10,000 yuan of industrial output value, urbanization rate, population growth rate, green road water quota, urban domestic water quota, rural domestic water quota, agricultural irrigation water quota, sewage treatment rate, sewage reuse rate, desalination water capacity, diversion water supply, and storage water supply) are selected as decision variables. The dynamic changes in Qingdao's water resources carrying capacity are simulated by changing the values ​​of the decision variables. For details on the specific distribution of the selected key control variables in the sustainable utilization system of coastal city water resources, see Figure 2 (The bold fonts in the figure are key control variables).

[0072] This study designed four urban water resource utilization plans: natural continuation, economic development, water conservation, and comprehensive development.

[0073] (1) Natural continuation plan: No measures are taken, and the indicator values ​​of the decision variables in the plan maintain the current development trend.

[0074] (2) Economic development plan. Vigorously promote economic development, put economic development in the top priority position, and improve the speed of economic development by optimizing the industrial structure. The growth rate of industrial output value in Qingdao from 2011 to 2019 reached its maximum in 2012, reaching 15%. Therefore, in this plan, the growth rate of industrial output value will be increased to 15%. By 2030, the urbanization level will be increased to 95%, and other parameter indicators will remain unchanged.

[0075] (3) Water-saving scheme. We should consider the rational development and utilization of water resources and protect existing resources and the environment. We should change the development strategy, reduce the speed of economic development, limit the growth rate of urban population, improve the treatment rate and reuse rate of domestic sewage and industrial wastewater, adjust the water quota, and develop water-saving agriculture. By 2030, the sewage treatment rate in Qingdao will be increased to 100%, the sewage reuse rate will be increased to 50%, the rural per capita domestic water quota will be reduced to 40L / (person·d), the urban per capita domestic water quota will be reduced to 70L / (person·d), and the farmland irrigation water quota will be reduced to 450m 3 / hm 2 .

[0076] (4) Comprehensive development plan. Under the premise of rational development and utilization of water resources, taking into account the above three plans, by 2030, Qingdao's sewage treatment rate will be increased to 100%, sewage reuse rate will be increased to 50%, urbanization level will reach 95%, industrial output value growth rate will be maintained at 15%, and farmland irrigation water quota will be reduced to 450m3. 3 / hm 2 The per capita domestic water quota in rural areas will be reduced to 40 L / (person·d), and the per capita domestic water quota in urban areas will be gradually reduced to 70 L / (person·d).

[0077] According to the above scheme, the relevant parameters of the model were adjusted and the Qingdao water resources carrying capacity model was run. The simulation results are shown in Figure 4 .

[0078] Depend on Figure 4 From the natural continuation scenario (a), it can be seen that from 2016 to 2030, the total water supply and total demand of Qingdao City will increase over time, but the total water demand will be higher than the total water supply, that is, the supply-demand gap is <0, and the gap is getting bigger and bigger. In 2030, the total water demand of Qingdao City is 1.191 billion m 3The total water supply is 1.103 billion m 3 , the gap between supply and demand reached 88 million m 3 , Qingdao is in a state of water shortage, and the water supply will not meet the requirements of social economy.

[0079] Depend on Figure 4 From the economic development scenario (b), it can be seen that the rapid economic development has increased the demand for water resources. From 2015 to 2030, the total water demand in Qingdao City has always been higher than the total water supply, that is, the supply-demand gap is <0. In 2030, the total water demand will reach 1.701 billion m 3 , while the available water resources are only 1.139 billion m 3 , the gap between supply and demand reached 562 million m 3 During this period, the economy develops rapidly, but the water shortage situation in Qingdao will become more severe.

[0080] The water shortage in both the natural continuation and economic development options is mainly solved by diverting water from other places. According to relevant planning data of Qingdao City, Qingdao City plans to divert 477 million m3 of water from other places by 2020. 3 In 2017, Qingdao City has transferred 530 million m3 of water from other basins. 3 , far exceeding the planned water diversion volume. In addition, the lower reaches of the Yellow River have been dry many times in recent years, and the amount of water that can be diverted from the Yellow River has decreased year by year. Therefore, without taking measures to save water and develop other water resources, it is difficult to meet Qingdao’s water resource needs by simply diverting water resources, and it cannot fundamentally solve Qingdao’s water resource shortage problem.

[0081] Depend on Figure 4 It can be seen from the water-saving scheme (c) that through the implementation of various water-saving measures, the total water demand of Qingdao City has been greatly reduced. In 2030, the total water demand of Qingdao City will be 854 million m 3 The total water supply is 1.243 billion m 3 The total water supply in the year is always greater than the total water demand, that is, the supply-demand gap is > 0, which shows that the water supply and demand balance in Qingdao has been effectively alleviated, and water resources have basically been reasonably developed and utilized, but the economic development of this plan is slow.

[0082] Figure 4 The medium (d) comprehensive development plan combines the above three plans, implements various water-saving measures, increases investment in sewage treatment and sewage reuse, strives to improve sewage utilization, and does not restrict economic growth and increase urbanization. It can be seen that by 2030, the total water demand of Qingdao City will be 1.35 billion m 3 The total water supply is 1.393 billion m 3 , the gap between supply and demand is 42 million m 3, the supply and demand of water resources are basically balanced, and the development and utilization of water resources in Qingdao is relatively reasonable. In comparison, the comprehensive development plan comprehensively considers measures such as water conservation, sewage treatment, and optimization of industrial structure, which not only alleviates the situation of water shortage, but also promotes the improvement of Qingdao's overall economic level, and utilizes the coordinated development of Qingdao's social, economic and environmental resources. Compared with the first three plans, this study believes that this plan is desirable and can be used as a water resource utilization plan for Qingdao.

[0083] 4. Analysis of indicator change trends.

[0084] When adjusting key variables, we must meet the requirements of sustainable use of urban water resources and take into account the coordinated development of urban population, resources, environment and economy. Therefore, we must first consider implementing various water-saving measures and technologies to achieve the purpose of reducing urban and rural domestic water quotas, water consumption per 10,000 yuan of industrial output value, green road water quotas, and farmland irrigation water quotas; secondly, we must not limit the growth rate of urban economic development and urbanization levels; at the same time, we must increase the intensity of urban sewage treatment and rainwater collection, improve the sewage recycling rate, develop seawater desalination technology and industry, and scientifically construct water diversion and storage projects to enhance the city's water supply capacity as a whole.

[0085] (1) Economic development related indicators. Figure 5 It can be seen that the urbanization rate and urban population of Qingdao City show a stable increasing trend from 2011 to 2030. Among them, the urbanization rate will reach 0.95 by 2030, and the urban population will reach 9.92 million. The increase in urbanization rate and urban population will inevitably lead to an increase in urban water consumption, urban road area, and urban environmental water demand, which will in turn lead to an increase in total water demand.

[0086] (2) Available water resource system. Figure 6 It can be seen that during the period 2011-2030, the surface water supply in Qingdao City has changed relatively little, except for the 2015 surface water supply of 570 million m 3 , and the rest of the years were between 600 and 700 million m 3 In order to protect groundwater resources and ensure sustainable use, the groundwater supply in Qingdao City decreased significantly from 380 million m3 to 2015. 3 Reduced to 240 million m 3 , reduced by 140 million m 3 In order to further alleviate the water shortage crisis in Qingdao, the amount of wastewater treatment and reuse in Qingdao has shown a steady growth trend. It is expected that by 2030, the amount of wastewater treatment and reuse will increase to 360 million m 3With the development and improvement of seawater desalination technology, combined with Qingdao's locational advantages and policy support for desalinated water resources, Qingdao's seawater desalination capacity will show an increasing trend during 2020-2030, and it is estimated that the seawater desalination capacity will increase to 150 million m3 by 2030. 3 .

[0087] (3) Agricultural water system. With the implementation of the strictest farmland protection system and land conservation system, Qingdao City has further increased its efforts to revitalize existing land while strictly controlling the increase in land. Figure 7 It can be seen that the agricultural irrigation area in Qingdao is increasing during the period 2011-2030. Assuming that the irrigation water quota is 450m 3 / hectare remains unchanged, its agricultural water demand will inevitably increase with the increase of farmland irrigation area. According to the SD model, Qingdao’s agricultural water demand will increase to 170 million m3 by 2030. 3 .

[0088] (4) Industrial water system. Figure 8 It can be seen that Qingdao's industrial output value increased significantly during the period 2011-2030. It is estimated that the trend of industrial output value increase will be particularly obvious after 2019. At the same time, Qingdao's industrial water demand will continue to increase during the period 2011-2030, and it is expected that industrial water demand will increase to 760 million m by 2030. 3 . With the increase in industrial water efficiency, the corresponding industrial wastewater discharge is also increasing, but the increase is weaker than the increase in industrial water demand. In terms of water consumption per 10,000 yuan of industrial output value, as Qingdao vigorously promotes the construction of water-saving enterprises, water-saving irrigation areas, water-saving units, and promotes water-saving technologies and water-saving equipment, Qingdao's water resource utilization rate will be significantly improved, and it will be possible to support economic and social development with less water consumption. Therefore, the water consumption per 10,000 yuan of industrial output value will be reduced from 1.44m in 2011 to 1.44m in 2012. 3 / Ten thousand yuan will gradually decrease and is expected to drop to 0.4m by 2030 3 / 10,000 yuan.

[0089] (5) Domestic water system. Fig. 9 It can be seen that during the period 2011-2030, Qingdao's urban domestic water demand showed an increasing trend from 2011 to 2016, and a decreasing trend from 2016 to 2020; due to the combined influence of the reduction in urban water quotas and the increase in urban population, its urban domestic water demand will be basically stable from 2020 to 2030, with a small change range.

[0090] Assuming that the domestic sewage discharge coefficient is a constant value of 0.98, the change trend of domestic sewage volume is similar to that of domestic water demand. In addition to a leap-forward increase in 2015-2016, Qingdao's urban domestic water quota will continue to decrease from 2011 to 2030 as Qingdao implements the goal of building a water-saving city and protecting the water environment. By 2030, the urban domestic water quota will be reduced to 70m3. 3 / (person / day). The rural domestic water quota is decreasing and will be reduced to 40m3 by 2030. 3 / (person·day). As the rural population decreases, the rural living water demand also shows a decreasing trend.

[0091] (6) Urban environmental water system. Fig.10 It can be seen that during the period of 2011-2030, as the road area in Qingdao increases, the water consumption for road watering will increase. It is expected that by 2030, the water consumption for road watering will increase to 130 million m 3 According to Qingdao's overall urban planning, with the increase in the area of ​​ecological green space, public green space, production green space and protective green space in Qingdao, the corresponding water consumption for watering green space will increase significantly. The model predicts that the increase in water consumption for watering green space from 2021 to 2030 will be significantly higher than that from 2011 to 2020. Affected by factors such as road watering and watering green space, Qingdao's urban environmental water demand will show an upward trend and is expected to increase to 147 million m by 2030. 3 .

[0092] (7) Wastewater treatment and reuse system. Fig.11 It can be seen that during the period 2011-2030, the total amount of sewage in Qingdao is increasing, and it is estimated that by 2030 the total amount of sewage in Qingdao will reach 710 million m 3 With the improvement of sewage treatment standards and technologies, Qingdao's sewage treatment rate will reach 100% by 2030. During this period, Qingdao's sewage treatment volume will increase.

[0093] In this embodiment, according to the actual status of water resources development and utilization in Qingdao, 13 variables including industrial output value increase rate, water consumption per 10,000 yuan of industrial output value, urbanization rate, population growth rate, green road water quota, urban domestic water quota, rural domestic water quota, agricultural irrigation water quota, sewage treatment rate, sewage reuse rate, desalination water capacity, diversion water supply, and storage water supply are selected as key control variables of the SD model, and a comprehensive development plan suitable for the sustainable utilization of water resources in Qingdao is proposed. In the comprehensive development plan, while implementing various water-saving measures, the investment in sewage treatment and sewage reuse will be increased, and efforts will be made to improve the sewage utilization rate, while not restricting the economic growth rate and increasing the urbanization rate. According to the above principles, by 2030, Qingdao's sewage treatment rate will be increased to 100%, the sewage reuse rate will be increased to 50%, the urbanization level will reach 95%, the industrial output value growth rate will be maintained at 15%, and the farmland irrigation water quota will be reduced to 450m 3 / hm 2 , the rural per capita domestic water quota is reduced to 40 L / (person·d), and the urban per capita domestic water quota is gradually reduced to 70 L / (person·d). The final plan concluded that by 2030, the total water demand in Qingdao will be 1.35 billion m 3 The total water supply is 1.393 billion m 3 , the gap between supply and demand is 42 million m 3 , the supply and demand of water resources are basically balanced, and the development and utilization of water resources in Qingdao is relatively reasonable.

[0094] Example 3: Generalization of Qingdao City's water resources optimization allocation plan

[0095] The water resources optimization configuration scheme of this embodiment is a further optimization of the sustainable utilization system of water resources in Qingdao in Example 2, and a quantitative application analysis of the multi-objective problem optimization method in the sustainable utilization of water resources is used, that is, the key control variables are adjusted in step S104 of the construction method of the sustainable utilization system of water resources in coastal cities of the present invention to meet the supply and demand balance requirements, providing an important reference.

[0096] The optimal utilization of water resources in Qingdao involves multi-dimensional coordination relationships at different levels and subsystems of the complex giant system of human-ecology-environment-society-economy. It is a typical semi-structured, multi-level, multi-objective group decision-making problem. The maximum comprehensive benefit of economic benefit, social benefit and environmental benefit is selected as the goal of the optimization model. Combined with the actual situation of water resources development and utilization in Qingdao, the order of water resources utilization in Qingdao is proposed ( Fig.12 ) and the general plan for sustainable use of water resources in Qingdao:

[0097] (1) Based on the current status and conditions of water resources supply and demand in Qingdao, the recommended order of water supply for various water resources is: guest water > surface water > rainwater > recycled water > desalinated water > groundwater.

[0098] According to the expert scoring method, the judgment matrix of Qingdao water supply order coefficient is obtained (Table 3.1). The judgment matrix is ​​calculated by the cloud operator platform to obtain the eigenvector W = (0.52, 0.41, 0.31, 0.21, 0.63, 0.10), where the maximum eigenvalue λ max is 6.00, and the weights corresponding to the normalized water supply order coefficients of each water source in Qingdao are shown in Table 3.2. The consistency test CR value of the judgment matrix is ​​0, <0.1. The consistency test of the judgment matrix of the water supply order coefficient of Qingdao meets the requirements, that is, the weights of the water supply order coefficients of each water source in Qingdao are scientific and reasonable.

[0099] Table 3.1 Qingdao City Water Resources Type Importance Judgment Matrix

[0100]

[0101] Table 3.2 Water supply order coefficients of various water sources in Qingdao

[0102]

[0103] It should be noted that the relative importance of various water resources and the order of water supply are not static. For example, with the improvement of Qingdao's desalinated water quality standards, seawater desalination technology, and related supporting equipment, and the increase in water production, Qingdao's dependence on guest water will gradually decrease. At that time, the weight of desalinated water resources in Qingdao's water resources sustainable utilization system and the corresponding water supply order will increase and rise.

[0104] (2) Prioritize the use of guest water resources; while giving priority to the use of guest water resources, take into account the efficient use of surface water resources in the river basins under the jurisdiction of the city; guest water, surface water and groundwater resources are prioritized for domestic water use, and are used for industrial and agricultural water use. In addition, the overall urban water resource reserves are increased.

[0105] Qingdao's water allocation should give priority to satisfying people's drinking water needs, and make overall arrangements for industrial and agricultural production and other water use. The water equity coefficients for life, industry, agriculture, and ecological environment are shown in Table 3.3.

[0106] Table 3.3 Water use equity coefficient in Qingdao

[0107]

[0108] The order in which water is supplied to each user is proposed to be: domestic water > industrial water > agricultural water > ecological environment water.

[0109] (3) In the process of groundwater resource utilization, we should strengthen groundwater resource conservation, rationally control the exploitation of shallow groundwater resources, and strictly control the exploitation of deep groundwater resources.

[0110] (4) Rainwater resources are mainly used for urban ecological environment water use and to improve the ecological environment, such as urban cleaning, urban greening water, water landscape, etc. In addition, rainwater resources can also be used for groundwater recharge to increase groundwater levels and prevent or delay surface subsidence. At the same time, in order to conserve urban water resources, alleviate the pressure of urban water shortage, and effectively control urban rainfall runoff, it is recommended to improve the utilization rate of urban rainwater resources by improving and optimizing sponge city planning and construction.

[0111] (5) The base of recycled water resources is small and the water quality is relatively poor, so its use is limited. It is recommended that recycled water resources be used for ecological environment water, municipal water, industrial cooling water, etc. With the improvement of recycled water quality standards, recycled water resources can be used for agricultural irrigation in the future.

[0112] (6) Considering the sustainability and long-term use of regional water resources, it is recommended that desalinated water in Qingdao be mainly used for industrial purposes, supplemented by urban water allocation and strategic reserves, and that seawater desalination be made an important supplement to urban water supply and a strategic reserve water source. At the same time, desalinated water that has been deboronized, mineralized, and meets the health standards for human drinking water should be incorporated into the Qingdao municipal water supply network at a certain mixing ratio, as an important part of the city's public water supply in the future.

[0113] (7) From the perspective of planning and management, the sustainable use of urban water resources is analyzed. Standardization, refinement and differentiation of water supply management is an inevitable trend. The differentiation can be mainly reflected in the quality-based water supply.

[0114] With the rapid development of social economy, the water demand of Qingdao will continue to expand. Faced with such a tense water shortage situation, Qingdao should accelerate the construction of water source allocation network system, form a water resource allocation network system that radiates the whole city and mutually supports each other, and coordinate urban and rural water supply and increase water supply capacity while improving the regional water supply guarantee rate; at the same time, Qingdao has rich marine resources. With the development of seawater desalination technology and industry, it will gradually increase the amount of seawater desalination and the use of desalinated seawater; continue to increase sewage treatment and rainwater collection, improve the reuse rate of recycled water, and enhance water supply capacity in general.

Claims

1. A method for constructing a sustainable utilization system of water resources in a coastal city, characterized in that: The construction method is based on the key control variable method; the method is as follows: first, according to the water resources supply and demand and development and utilization types of coastal cities, the system is divided into a water supply system and a water demand system; the water supply system includes four subsystems: surface water supply system, groundwater supply system, recycled water supply system, and seawater desalination supply system; the water demand system includes four subsystems: agricultural water system, industrial water system, domestic water system, and urban environmental water system; Then, a sustainable utilization system of water resources in coastal cities is constructed, and the key control variables in the system are determined; the dynamic changes of the structure and efficiency of sustainable utilization of water resources in coastal cities are simulated by adjusting the key control variables; Finally, based on the adjusted key control variables, calculate whether the difference between water resources supply and demand in coastal cities meets the relationship of supply and demand balance; make the adjusted key control variables meet the goals of sustainable utilization of water resources in coastal cities and coordinated development of society, economy and ecological environment; The specific steps are as follows: (1) Water resources are classified according to the supply and demand of water resources and the types of development and utilization in coastal cities; the sustainable utilization system of urban water resources is divided into four water supply subsystems, namely, surface water supply system, groundwater supply system, recycled water supply system, and seawater desalination supply system, and four water demand subsystems, namely, agricultural water demand system, industrial water demand system, domestic water demand system, and urban ecological environment water demand system. The surface water supply is further divided into three types, namely, urban water storage, urban water diversion, and urban water extraction; the water supply system and water demand system need to include all water resources in the city; The mathematical expression of coastal city water resources classification can be summarized as follows: IN 城市可供水量 =In 地表水供水量 +W 地下水供水量 +W 再生水供水量 +W 淡化水供水量 IN 地表水供水量 =In 蓄水量 +W 引水量 +W 提水量 IN 城市总需水量 =In 生活需水量 +W 工业需水量 +W 农业需水量 +W 生态环境需水量 ; (2) Construct an "economic-social-ecological" system for the sustainable utilization of water resources in coastal cities and determine the key control variables of the system; follow the principles of scientificity, integrity and feasibility, and select variables that are located at the starting point of the system and play a key role as the key control variables of the system; (3) Simulate the dynamics of urban water resource utilization by adjusting key control variables; implement various water-saving measures without limiting economic growth and increasing the urbanization rate; (4) Based on the adjusted key control variables, calculate whether the urban water resources supply and demand gap meets the supply and demand balance relationship, and test whether it meets the development requirements of sustainable utilization of water resources in coastal cities and whether it meets the requirements of coordinated development of coastal cities' economy, society, resources and environment; if not, readjust the key control variables until they meet the requirements; The key control variables selected in step (2) must be located at the starting point of the system and must be variables that have a key impact on the sustainable use of urban water resources: industrial output value increase rate, water consumption per 10,000 yuan of industrial output value, urbanization rate, population growth rate, green space and road water quota, urban domestic water quota, rural domestic water quota, agricultural irrigation water quota, sewage treatment rate, sewage reuse rate, desalination water capacity, diverted water supply, and stored water supply.

2. The method for constructing a sustainable utilization system of water resources in coastal cities as claimed in claim 1, characterized in that: In the step (3), firstly, various water-saving measures and technologies are considered to be implemented to reduce the urban and rural domestic water quota, the water consumption per 10,000 yuan of industrial output value, the green road water quota, and the farmland irrigation water quota; secondly, the growth rate of the city's economic development and urbanization level is not restricted; at the same time, the city's sewage treatment and rainwater collection efforts are increased, the sewage recycling rate is improved, the seawater desalination technology and industry are developed, and the water diversion and storage projects are scientifically constructed to enhance the city's water supply capacity in general.

3. The method for constructing a sustainable utilization system of water resources in a coastal city as claimed in claim 1, characterized in that: In the step (4), the specific measures for adjusting the key control variables need to be combined with the actual development and utilization of water resources in coastal cities and the planning and development requirements, and follow the principles of scientificity, integrity and feasibility.

4. The "economic-social-ecological" system for sustainable utilization of water resources in coastal cities constructed by the construction method of the sustainable utilization system of water resources in coastal cities described in claim 1.

5. Application of the method for constructing a system for sustainable utilization of water resources in coastal cities as described in claim 1 in the planning and design related to sustainable utilization of water resources in coastal cities.

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