First, the environmental problems in the process of urban development
Cities are the product of the development of human social civilization to a certain historical period. Its emergence and development are determined by economic development and influenced by superstructure. In recent decades, the rapid growth of urban population and rapid economic development have caused a series of environmental problems:
1. The water pollution problem is outstanding.
Due to the rapid growth of urban population and the rapid development of industry, a large amount of sewage is directly discharged into the water without proper treatment, causing serious damage to the water environment. Recently, water pollution in China has been increasing. More than 850 rivers with monitoring data 1200 in China are polluted. Among the seven major water systems, the Liaohe, Haihe and Huaihe rivers are seriously polluted. 1, among 38 urban river sections, 1, 33 river sections are polluted to varying degrees. Across the country, 78% of the river reaches are not suitable for drinking water sources, 50% of the groundwater is polluted, and many cities such as Xi and Beijing have also experienced water supply crises. It is estimated that the economic losses caused by pollution in China reach 40 billion yuan every year.
2. Urban air quality has deteriorated seriously.
With the rapid development of industry and transportation and the extensive use of fossil fuels, dust, sulfur oxides, nitrogen oxides, carbon oxides, ozone and other substances are discharged into the atmosphere, which seriously deteriorates the air quality. China's air pollution belongs to "soot pollution", and the concentration of total suspended particulate matter in urban air in China generally exceeds the standard, with an average concentration of 309 μ g/m3; The concentration of sulfur dioxide is relatively high, and pollution in some cities is quite serious, with an average of 83 μ g/m3 in northern cities. Benxi, China, was once called "a city invisible to satellites" because of smog. However, excessive sulfides and nitrogen oxides in the atmosphere have caused acid rain in most parts of the country. The frequency of acid rain in Yibin, Changsha and other cities exceeds 90%, and the average PH value of rainfall in Changsha reaches 3.54. The arrival of acid rain not only destroyed the ecological environment, but also aggravated the corrosion and damage of buildings, railways and bridges, bringing huge losses to industry and agriculture. The greenhouse effect and ozone layer destruction caused by air pollution directly threaten human survival.
3. Solid waste is rampant, and the phenomenon of garbage siege is serious.
Human life and production produce a lot of solid waste. At present, China produces 660 million tons of industrial solid waste every year, including 30-40 million tons of hazardous waste, with a cumulative amount of more than 6.4 billion tons, occupying more than 500 million square meters of land. The annual output of domestic garbage is 1 ton, increasing at the rate of 7-8% every year. Due to the open-air accumulation of solid waste in China, two-thirds of the cities in China are surrounded by garbage. Stacking solid waste everywhere not only hinders the view, occupies land and spreads diseases, but also seriously pollutes the environment and intensifies the pollution of water bodies and atmospheric soil.
4. Noise disturbing people is very common.
At present, with the rapid development of industry, transportation, culture and entertainment in China's cities, the phenomenon of noise disturbing people is becoming more and more prominent. According to the monitoring of 44 state-controlled cities, more than two-thirds of urban residents in China live in an environment with excessive noise, and the equivalent sound level of regional environmental noise is distributed in 5 1.5-65.8d B(A), with the average equivalent sound level of Luoyang, Datong, Kaifeng, Haikou and Lanzhou. The equivalent sound level of road traffic noise ranges from 68.0 to 76.3 dB (A).
Second, the urban environmental protection planning and its main contents
Based on the above-mentioned environmental crisis, people have gradually realized the relationship between urban planning and urban development in recent decades, and began to use scientific planning to guide urban construction. The proposal of urban planning overcomes the disorder, blindness and randomness of urban development in the past, and provides technical and legal guarantee for the healthy development of the city. Urban environmental protection planning is an important part of urban planning. It is a planning system based on the investigation and analysis of the nature, scale and development direction of the city and the present situation of urban environmental quality in the overall urban planning, with the goal of protecting human living environment, reducing pollution and saving resources. According to the general policy and strategy that China's environmental protection should adhere to the simultaneous planning, implementation and development of economic construction, urban and rural construction and environmental construction, and realize the coordination and unification of economic benefits, social benefits and environmental benefits, urban environmental protection planning should mainly carry out the following aspects:
1. Preliminary preparation for urban environmental protection planning
These preparations are the basis of urban environmental protection planning, including urban natural environment information, such as geographical location, ecological environment, meteorology, hydrology and so on. Social and economic conditions of the city, such as population and gross national product; Investigation and analysis of monitoring data of atmosphere, water body and noise, sources and accumulated amount of solid waste over the years, pollution control and other environmental conditions; Present situation analysis and functional zoning of urban ecological environment.
2. Comprehensive air pollution control planning is to divide the functions according to the present situation and development trend of urban air quality, and calculate the maximum allowable emissions and reductions of each functional area according to the proposed environmental objectives, so as to formulate pollution control planning. To control air pollution, we should determine the primary pollutants according to the energy structure and traffic conditions of the city, that is, pollutants with high concentration, wide range and great harm, so as to control them in a targeted manner and prescribe the right medicine. At present, air pollution in most cities in China is mainly caused by coal burning and automobile exhaust, and the primary pollutants are sulfur dioxide and total suspended particulate matter. Therefore, the long-term goal of the planning should be to improve the backward olefin coal mode, improve the combustion efficiency, try to use gas fuel, briquette, solar energy, geothermal energy and other pollution-free or less polluting energy sources, implement regional central heating, eliminate small chimneys of thousands of households, improve the road hardening rate, and create a smoke-free control area by strengthening pollution control and improving pollution control technology. Adjust the industrial layout and make scientific and convenient use of atmospheric environmental capacity according to the law of atmospheric self-purification; Strengthen pollution source control and reduce pollutant discharge; Reduce automobile exhaust pollution through technical and administrative means; Improve the urban greening rate, select tree species with good pollution resistance, and vigorously develop plant purification.
3. Comprehensive water pollution control planning
Based on the investigation and analysis of the present situation of water pollution, the comprehensive water pollution control plan is to calculate the maximum allowable discharge and determine the best control scheme according to the environmental capacity of the receiving water body. At present, the degree of water pollution in seven major water systems in China is increasing and the scope is expanding. 1996 The polluted water of the Yangtze River, the Yellow River, the Huaihe River and the Songhua River 1996, the national industrial wastewater discharge was 50.29 billion tons, including 7.04 million tons of chemical oxygen demand, 2,457 tons of heavy metal1565,438 tons, cyanide and tens of thousands of tons of pollutants such as arsenic, phenol and oil. Domestic sewage accounts for about 24% of the total annual discharge, and the main pollutant is organic matter. According to the specific situation of water pollution in China, the comprehensive water pollution control plan should reform the backward production mode, adopt the technology of less waste and no waste, realize clean production, improve the sewage treatment effect and resource utilization rate, reduce sewage discharge, build effective sewage treatment facilities, strengthen the treatment of industrial wastewater and domestic sewage, and finally achieve the goal of effectively protecting water resources.
4. Comprehensive improvement planning of urban solid waste
The comprehensive treatment planning of solid waste is to implement the comprehensive utilization rate, treatment and disposal index system of all kinds of solid waste, and formulate the final treatment countermeasures according to the environmental objectives. At present, many cities in China are surrounded by solid waste, so it is urgent to solve the problem of solid waste. The purpose of solid waste comprehensive treatment planning is based on the economic bearing capacity of cities and urban solids.
Below is the subtitle.
With the help of pixel-level precision table drawing tools, web page layout can be designed more quickly and conveniently. Using the same tools as pencils and erasers to create tables, you can design tables of any size and shape directly on the web page. Using table drawing tools can flexibly design high-precision page layout, so that the table can match the page content. Tables can contain anything you like, including images, text, multimedia files and even nested tables. These complex web page layouts don't need any handwritten HTML coding.
Below is the subtitle.
With the help of pixel-level precision table drawing tools, web page layout can be designed more quickly and conveniently. Using the same tools as pencils and erasers to create tables, you can design tables of any size and shape directly on the web page. Using table drawing tools can flexibly design high-precision page layout, so that the table can match the page content. Tables can contain anything you like, including images, text, multimedia files and even nested tables. These complex web page layouts don't need any handwritten HTML coding.