Environmental Impact Assessment of Land Use Planning Based on "3S" Technology —— A Case Study of Ecological Sensitivity Zoning in Fengdu County, Three Gorges Reservoir Area

(School of Resources and Environment, Southwest University, Chongqing, 4007 15)

On the basis of introducing the application of "3S" technology in land use planning, taking Fengdu county in the Three Gorges reservoir area as an example, the application of "3S" technology in environmental impact assessment of land use planning was further elaborated through ecological sensitivity zoning of Fengdu county, with a view to providing useful reference for rational land use planning.

Key words: land use planning; Environmental impact assessment; "3S" technology; Fengdu County

The Environmental Impact Assessment Law of the People's Republic of China came into effect on September 6, 2003. Article 7 of Chapter II of the Law stipulates that "when planning, the relevant departments of the State Council and the local people's governments at or above the municipal level with districts and their relevant departments shall organize environmental impact assessment and prepare relevant plans for land use, regional, river basin and sea area construction and utilization. This law formally established planning environmental impact assessment as China's environmental impact assessment system. In the past, China's environmental impact assessment was mostly carried out around construction projects, and the research on environmental impact assessment of land use planning was still blank in China. At present, China is starting a new round of overall land use planning, which requires us to carry out research on environmental impact assessment of land use planning and establish a scientific environmental impact assessment system and method.

"3 S" technology refers to the integration technology of geographic information system (GIS), remote sensing (rs) and global positioning system (GPS). Since 1990s, "3 S" technology has developed rapidly and been widely used. "3 S" technology is the main means to realize the informationization of land use planning and the modernization of land use planning management. However, due to the reasons of technology and talents, only part of "3S" technology was used in the planning process in the past, which is far from the requirements of land and resources informatization. Therefore, the land use planning management information system was established after the planning work was completed. Research purposes: It is considered that the new round of land use planning should make full use of "3S" technology, improve the informatization level of land use planning, and fully adapt to the needs of land use planning under the new situation.

1 regional overview

Fengdu County is located in the center of the Three Gorges Reservoir Area and the territory center of Chongqing. The landscape of the county consists of a series of folded mountain systems, with the Yangtze River passing through it. The county covers an area of 2904.07 square kilometers, of which hills account for 3 1.7%, low mountains account for 39.4% and Zhongshan accounts for 28.9%. The climate belongs to the humid monsoon climate in the middle subtropical zone, with mild climate, abundant rainfall, distinct four seasons, abundant heat and obvious three-dimensional climate throughout the year. Annual average temperature 18.5℃, annual average precipitation 1 123.4mm, frost-free period 3 18 days, sunshine hours 1365438+. Fengdu County is located on the tourist hotline of the Three Gorges of the Yangtze River. The implementation of the economic strategy with the development of tourism as the guide has made the county's social economy develop rapidly and the living standards of urban and rural residents have improved significantly. With the completion of the Three Gorges Project, the natural ecological environment and economic and social status of Fengdu County will undergo great changes. Due to the specific geological structure and highway construction, small and medium-sized water conservancy projects, resettlement and town building, quarrying and mining and other human engineering activities in the county, the geological environment in this area has been transformed and destroyed to varying degrees, the geological environment conditions have deteriorated day by day, and the land use has changed greatly. At the same time, after the completion of the reservoir, the self-purification ability of the water body will be greatly weakened, which will easily lead to sediment deposition and water pollution, which will adversely affect the safety of people's lives and property in the reservoir area. Fengdu county is located in the center of the Three Gorges reservoir area, and the Yangtze River flows through the territory for 47 kilometers. Its environmental situation is directly related to the long-term stability of the Three Gorges Project and the safety of people's lives and property in the whole reservoir area.

2 Based on "3S" technology, environmental impact assessment analysis of land use planning

The main tasks of this round of land use planning environmental impact assessment are: ① to investigate regional ecological and environmental problems and analyze resource supply and environmental capacity. Investigate the main ecological environment problems in this area, especially the land ecological environment problems, and analyze the severity, distribution, scope and harm of important ecological environment problems; Investigate the supply of the main restricted resources in this area; Investigate the regional environmental capacity. ② Analyze the relationship between regional land use and ecological environment. Analyze the impact of regional land use scale, structure and layout, infrastructure construction, land development and consolidation, ecological construction projects and other land use activities on the ecological environment. ③ Put forward land use control indicators and spatial control measures that are beneficial to regional environmental protection and ecological construction. According to the conditions and characteristics of regional ecological environment and land use, an environment-friendly land use model is put forward. Put forward a reasonable layout from the perspective of environmental protection and ecological improvement; According to the regional ecological environment problems and natural, economic and social conditions, this paper puts forward reasonable ecological construction principles, standards, objectives, land use arrangements and policy support suggestions. Based on this, in this round of land use planning EIA, ecologically sensitive zoning should be considered, and the spatial layout of land use should be rationally planned to provide useful reference for protecting the ecological environment. The refinement of this part is mainly realized by "3S" technology, which mainly includes remote sensing technology, that is, multi-spectral satellite remote sensing data, radar remote sensing data, aerial survey remote sensing data, global positioning system, field observation and geographic information system, so as to objectively and accurately provide data such as land type, land use, landform type, vegetation coverage and urban distribution. , and the planning scope of ecological zoning.

2. 1 Land use planning based on "3S"

Land use planning is a kind of spatial planning. With the help of "3S" technology, not only the basic data can be processed, but also the spatial data model of land suitability evaluation can be established with the support of spatial analysis model to assist in the preparation of land use planning with optimal time and space.

2. 1. 1 Spatial analysis model of overall land use planning

(1) Land suitability evaluation based on GIS. Land suitability evaluation is a process of evaluating whether land is suitable to determine the type of use under a certain management level. By evaluating the suitability of land units for different land use types, we can make clear the land suitability of each land use type and its quantity, quality and structural characteristics, reveal the restrictive factors affecting the determination of land use types and their limiting degrees, and thus provide a basis for the overall land use planning. Traditional land suitability evaluation is based on collected data, personal experience and certain principles. Therefore, the evaluation results are subjective, and the map of the evaluation results needs to be drawn by hand, and the related work such as area calculation and statistical analysis is time-consuming and laborious and prone to errors. Using GIS technology to evaluate land suitability can overcome the above problems. With the help of GIS technology, according to a certain mathematical model, making full use of the existing data resources, the land suitability is evaluated by single factor and multi-factor comprehensive evaluation, and the classification and grading of land suitability in the evaluation area are realized. It has related statistics, analysis, planning and management functions, integrates data management, land evaluation and office automation, and effectively promotes the standardization, systematization and modernization of land suitability work.

(2) Spatial prediction model Land use planning is strategic and needs to accurately predict the land supply and demand in a period of time. Scientific forecasting models and methods are the premise of successful forecasting. Traditional prediction mostly adopts economic mathematical models such as regression, smoothing, curve fitting and grey prediction, and there are nearly 20 kinds in four categories. These models take the administrative unit as the basic unit, regard the spatial entity as a point, and the calculation results deviate from the actual situation.

(3) The land spatial allocation model based on GIS makes use of the spatial analysis function of GIS, which is helpful to make the most effective use of land resources in space. The following standards can be used to guide the land allocation of land use planning: ① to meet the needs of urban development while taking into account the protection of high-quality agricultural land; ② The choice of urban development land should be reasonable. First, the most suitable land should be developed. ③ Properly solve the contradiction between different land use types; (4) Land development should be planned to prevent disorderly spatial layout. The above criteria for maximizing spatial benefits are to save land resources. Firstly, the spatial distribution of agricultural suitability and urban development suitability in the study area is obtained through the evaluation of land resources. The calculation of land suitability takes into account factors such as soil, topography, traffic and land use. If other constraints are not considered, the land use mode should be consistent with the land suitability. In land planning, the most common problem is how to solve the conflict between urban land and agricultural land, and the land suitable for urban development is often the most suitable for agricultural production. According to the suitability of land, the contradiction between urban development and cultivated land protection can be reasonably solved by using GIS, which is a multi-objective spatial decision-making problem. The linear segmentation method proposed by Eastman and others can be used to solve this problem.

2. 1.2 planning scheme based on GIS

The land planning scheme supported by GIS has the characteristics of modeling, quantification, diversification and dynamics, and the planned scheme is more scientific. The determination of planning scheme always involves the simulation, evaluation and comparison of different schemes. GIS can automatically generate planning schemes with different parameters according to the existing information, planning model and the last round of planning, display different schemes in the form of graphs and tables, and simulate the results of implementing different schemes. It is worth mentioning that land use planning involves the vital interests of every citizen and the planning of social sustainable development. Public participation is very important to the scientificity of the planning scheme and the implementation of the final scheme. In view of this, the planning scheme is expressed by visual means such as Web GIS, electronic map and virtual geographical environment, so that different user groups can deeply understand the scheme and put forward suggestions for modification. Land use planning experts and management decision-making departments can carry out collaborative planning with the support of GIS and other technologies. In the collaborative planning environment, not only the planning scheme is visualized, but also the operating tools for discussing the environment and modifying the planning scheme are provided.

2. 1.3 making of planning drawing

According to the relevant provisions of the state, the basic maps of the main map results of the overall land use planning include the current land use map, the land use planning map, the basic farmland protection map and the urban land scale map. GIS has strong cartographic ability, and can output the required map according to the planning scheme. Because the mapping function of GIS does not meet the requirements of land use planning map in terms of graphic symbols and color distribution, it is necessary to improve the mapping module of GIS according to the relevant provisions of land use planning map, or connect the corresponding mapping software with GIS database to obtain relevant information from GIS for mapping and output various required planning maps. The combination of GIS and RS can make maps with higher visibility, and remote sensing data is more timely and visible than map data. Remote sensing data is used as the background data of land use planning map, which is convenient for users who generally use map results to understand the planning results. There are many intermediate achievements in land use planning based on "3S", most of which are expressed in graphic form. Although the Regulations regard these achievements as necessary achievements, they are important resources and foundations for land use planning. GIS also provides tools and symbol libraries for making these maps, and these results can be easily compiled.

2.2 Example of Eco-sensitive Zoning

In order to ensure the sustainable utilization of natural resources and the contradiction between coordinated development and protection, based on "3S" technology and according to four factors (see table 1), the land in Fengdu County is divided into four types: the most sensitive area, sensitive area, low sensitive area and insensitive area (Figure 65438

Table 1 Ecological Sensitivity Analysis of Land Use in Fengdu County

Figure 1 Ecological Sensitivity Zoning of Fengdu County

2.2. 1 most sensitive area

Generally, it is a river and its affected area, with a slope of more than 20% and a high ecological value. It is mainly distributed in the south of Fangdou Mountain, Gaojia Town and Xingyi Town. This area is extremely sensitive to urban development and construction. Once destructive interference occurs, it will not only affect this area, but also bring serious consequences to the whole regional ecosystem, which belongs to the key area of natural ecosystem.

Sensitive area

Generally, the woodland in gentle areas is sensitive to human activities, and the ecology is difficult to recover, which plays an important role in maintaining good functions and climate environment in the most sensitive areas. Therefore, it should be carefully developed. It is mainly distributed in Zhongshan area south of the Yangtze River, Shi Zhi Town north of the Yangtze River, Shetan Town and Baohe Township in the northwest of the Yangtze River and other high-yield fields in hilly areas.

2.2.3 Low sensitive area

Generally, it is an area of cash crops such as barren hills, shrubs and grass forests, which can withstand certain human interference, but serious interference will lead to soil erosion and related natural disasters, and the ecological recovery will be slow; Low sensitive areas are distributed in many towns, but unreasonable development is easy to transition to sensitive areas.

Insensitive region

Mainly abandoned farmland in dry land, it can withstand a certain intensity of development and construction. The land can be developed for various purposes, mainly distributed in the northeast of the Yangtze River and near the urban area.

3 Conclusion

For some time, backward land information technology has been an important factor restricting the development of environmental impact assessment of land use planning in China, especially the lack of real-time dynamic information, which can not make changes in land use information and adjustments in planning schemes in time. "3S" technology is an ideal technical support means for environmental impact assessment of land use planning, which can effectively analyze land use planning.

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