(1. School of Geographical Sciences, Southwest University, Chongqing, 400715; 2. Key Laboratory of Ecological Environment in Three Gorges Reservoir Area of Southwest University, Chongqing, 400715; 3. Economic and Social Research Center of Southwest University Three Gorges Reservoir Area, Chongqing, 4007 15)
Abstract: Based on the concept of sustainable utilization of urban land, the urban land utilization system is evaluated quantitatively and scientifically. The evaluation index system of urban land sustainable use is established from five aspects: land productivity, production stability, resource and environmental protection, economic feasibility and social acceptability, and a preliminary study is made by mathematical methods. Taking Chongqing as an example, the sustainable land use in this city from 2000 to 2004 was analyzed and evaluated vertically. The results show that the level of sustainable land use in Chongqing is constantly improving. According to the evaluation results, this paper analyzes the problems existing in the sustainable use of urban land in Chongqing, and puts forward some measures to promote the sustainable use of urban land.
Key words: sustainable use of urban land; Index system; Coordination function method; Longitudinal comprehensive evaluation
China is currently in the take-off stage of urbanization. From 1978 to 1998, the number of cities in China increased from 223 to 668, and the urbanization level also increased from 17.9% to 30.4% [1]. The improvement of urbanization level has promoted the rapid economic development of China and solved a large number of rural surplus labor. However, at present, due to institutional and management reasons, there are some problems in the process of urbanization in China, such as unreasonable urban scale growth, inefficient land use, unreasonable land use structure, serious idle land, declining environmental quality, and unresolved equity issues.
The chapter "Promoting the development of stable human settlements" in the Agenda of China People and China 2 1 Century published by China puts forward eight specific contents of the sustainable development of human settlements: ① Providing adequate housing for all; (2) Improving the management of human settlements, with special emphasis on urban management, requires innovative urban planning through various means to solve environmental and social problems; ③ Promoting the planning and management of sustainable land use; ④ Promote the unified construction of environmental infrastructure such as water supply, sewage discharge, drainage and solid waste management; ⑤ Promote recyclable energy and transportation systems in human settlements; ⑥ Strengthen the planning and management of human settlements in disaster-prone areas; ⑦ The basis of promoting sustainable construction activities; (8) Encourage the development of human resources and improve the development capacity of human settlements. The above eight aspects actually put forward specific requirements for the sustainable development of human settlements, and also put forward corresponding requirements for the sustainable use of land in human settlements. Because the sustainable development of human settlements, cities and urban land use systems are closely related.
In the process of urban land use in China, it is the basic idea of sustainable development of urban land use system in China to realize the suitability of natural conditions, economic effectiveness, social acceptability, fairness and ecological environment quality, and to maintain the reasonable state of urban land use system in an orderly extension in time [2]. In this paper, the urban land use system is evaluated quantitatively and scientifically, and the evaluation index system of urban land sustainable use is established from five aspects: land productivity, production stability, environmental resources protection, economic feasibility and social acceptability, and a preliminary study is made by mathematical methods. Taking Chongqing as an example, the sustainable utilization of urban land was analyzed and evaluated vertically.
1 Construct the evaluation index system of urban land sustainable use
1. 1 principles for the construction of evaluation index system
The establishment of evaluation index system is actually to simulate the operation mechanism of the evaluated object on the basis of fully analyzing its basic structure and characteristics. The objective land use system itself is scientific, comprehensive and dynamic. Therefore, the design of evaluation index system should not only conform to the general principles of evaluation system, but also summarize the basic structure and characteristics of the evaluated object [2].
1. 1. 1 science
In order to ensure that the evaluation results conform to the objective reality, an index system will be established on a scientific basis, and an analytical model that can fully reflect the internal mechanism of sustainable land use will be adopted, and indicators that can reflect the meaning of sustainable urban land use and the degree of target realization will be put forward, with special attention to establishing the logical relationship between indicators.
1. 1.2 comprehensive system
Sustainable use is a systematic and comprehensive requirement, and the index system will comprehensively reflect all aspects of sustainable use of urban land, including population, resources, environment, economy and society and their coordination, so that the evaluation target layer, criterion layer, index layer and meta-index layer form a distinct organic whole.
1. 1.3 dynamic
The sustainable use of urban land is both a goal and a process. Therefore, the establishment of the index system will have dynamic simulation. Dynamic indicators comprehensively reflect the present situation, characteristics and trends of sustainable use of urban land.
1. 1.4 representativeness and conciseness
The selection of indicators should emphasize typicality and representativeness, and avoid selecting derivative indicators with similar meanings, duplication or combination with other indicators, so as to make the indicator system relatively simple and easy to use [3].
1. 1.5 Availability
In the selection of indicators, we should pay attention to the operability of indicators, that is, whether the selected indicators can be obtained under the existing technical and economic conditions.
1. 1.6 comparability
Comparability requires comparability of all indicators in the system, and comparability is the basis and prerequisite for obtaining accurate results.
Construction of 1.2 index system
There are several methods to form the index system, such as PSR method, system analysis method, target decomposition method and sustainable utilization three-benefit analysis method. Here, the target decomposition method is chosen to construct the evaluation index system. In order to grasp and set the basic points of evaluation as a whole, the basic framework of evaluation index system is designed according to the general principles of establishing index system and the basic objectives of urban land sustainable use evaluation. The framework follows the general principles of FAO《FESLM, and sets evaluation indicators from five aspects: land productivity, production stability, economic feasibility, resource and environmental protection and social acceptability. According to the actual situation of urban land use in Chongqing, 53 factors were selected from these five aspects to participate in the evaluation of crops, and the evaluation index system of sustainable urban land use in Chongqing was established (table 1).
Table 1 Evaluation Index System of Urban Land Sustainable Utilization in Chongqing
2 comprehensive evaluation method of urban land sustainable use
On the basis of the evaluation index system, combined with the actual situation of the evaluation object, certain analysis methods are selected for basic judgment, and the evaluation results are analyzed and studied to form an evaluation conclusion.
2. 1 index data collection
Generally, there are the following methods to collect index values.
(1) test method refers to inferring the data of the whole area from the sample data after statistical analysis and processing by testing the field sample points.
(2) Investigation method refers to obtaining the corresponding evaluation index data through experts and field investigation.
(3) Determining according to statistical data refers to obtaining data by consulting official statistical data.
(4) Remote sensing method obtains evaluation data by means of remote sensing measurement and analysis. Generally speaking, the indicators of natural resources can be collected through expert consultation and scientific experiments; Socio-economic indicators mainly obtain data through social surveys and statistical data; Environmental indicators are mainly obtained through scientific experiments [2].
2.2 Quantization and standardization of evaluation indicators
Some evaluation indicators are qualitative and some are quantitative, and sometimes the quantitative indicator value itself is not the value needed for evaluation, so it is necessary to quantify and convert the evaluation indicators. For qualitative social indicators, surveys and expert consultation are generally used to solve them. For example, the degree of public participation in land planning is divided into ten grades: 0 ~ 10 * * *, and the indicators of the survey year are graded by combining actual investigation with expert consultation.
The standardization of evaluation index can adopt range standardization, percentage standardization, fuzzy mathematics method, power conversion method, grading scoring method and so on. Percentage standardization is adopted here [2]. There are three situations between evaluation factors and evaluation objects:
(1) positive correlation, that is, the greater the factor index value, the more it can reflect the continuous situation;
(2) the inverse ratio, that is, the greater the factor index value, the worse the persistence;
(3) Moderate relation, that is, factor index value, has the best persistence in moderate value. In view of these three situations, the standardized processing formula of factor indicators is as follows:
(1) Positive factors:
Innovation of Land Information Technology and Development of Land Science and Technology: Proceedings of the 2006 Annual Conference of china land science Institution.
(2) adverse factors:
Innovation of Land Information Technology and Development of Land Science and Technology: Proceedings of the 2006 Annual Conference of china land science Institution.
(3) Mild factors
Let x be the median of a factor:
When Xi≥X,
Innovation of Land Information Technology and Development of Land Science and Technology: Proceedings of the 2006 Annual Conference of china land science Institution.
When Xi≤X,
Innovation of Land Information Technology and Development of Land Science and Technology: Proceedings of the 2006 Annual Conference of china land science Institution.
Where: the exponential value of a factor after treatment; Xi is the index value of a factor before treatment; Xmin is the minimum index of a factor before treatment; Xmax is the largest index of a certain factor before treatment.
The target value of each index is determined by combining international standards, design specifications, statistical data and empirical data. For example, refer to the national sustainable development standards, regional tenth five-year plan, 20 10 long-term plan, urban land classification and planning and construction land standards. See Table 2 for the standardized values of each single index obtained through calculation.
2.3 Determination of Index Weight
Because the above 53 meta-indicators have different contributions to the sustainable use of urban land, it is necessary to determine the weight of each indicator. There are many methods to determine the weight, such as expert scoring method, regression coefficient method, grey relational analysis method, analytic hierarchy process, principal component analysis method and relative weight method. Among them, Analytic Hierarchy Process (AHP) is a multi-level weight analysis decision-making method, which is based on an important principle in system theory-the hierarchy of the system. The urban land use system is regarded as a large system, and many factors are analyzed to divide the orderly level of each factor. Then experts are invited to objectively judge the factors at all levels, and then the quantitative expression of relative importance is given, and then a mathematical model is established to calculate the weight value of the relative importance of factors at all levels and sort them. Finally, planning decisions are made according to the ranking results, and measures to solve the problems are selected [4].
(1) Clarify the problem and construct the Analytic Hierarchy Process (AHP). To apply AHP, we should first select the most important key evaluation indicators from many complicated factors, and construct a multi-level index system according to their restrictive relations (see table 1), and then conduct hierarchical analysis according to the levels. Generally, it can be divided into target layer, criterion layer, index layer and meta-index layer.
(2) Construct a judgment matrix.
(3) Invite experts to fill in the judgment matrix.
(4) Sorting hierarchical documents. Its essence is to find the weight of single objective judgment matrix, that is, according to the judgment matrix filled by experts, calculate the weight of the related elements in the order of importance at this level.
(5) Overall ranking and consistency check of grades. By this method, the weight value of each meta-index can be obtained (Table 2).
Table 2 Standardized values and weights of evaluation indicators for sustainable urban land use in Chongqing
Note: The data in the table are calculated according to Chongqing Statistical Yearbook 200 1, Chongqing Statistical Yearbook 2002, Chongqing Statistical Yearbook 2003, Chongqing Statistical Yearbook 2004, Chongqing Statistical Yearbook 2005 and field survey data.
2.4 Comprehensive evaluation of sustainable land use
There are many methods to evaluate sustainable land use, such as artificial neural network method, coordination function method, compound ecosystem field theory, analytic hierarchy process, fuzzy evaluation method, multi-objective weight function method, regression model established by SPSS, time series analysis method of ARCH and ARIMA, etc. In this paper, the coordination function method of quadratic synthesis is used to evaluate the sustainable land use vertically [5]. The comprehensive evaluation function between each meta-index in the criterion layer is:
Innovation of Land Information Technology and Development of Land Science and Technology: Proceedings of the 2006 Annual Conference of china land science Institution.
The secondary comprehensive evaluation function is:
T=T C 1 +T C2 +T C3 +T C4 +T C5
Where w represents the weight of each index, t is the coordination degree of sustainable land use, and 0≤T≤ 1. Different T values have different degrees of sustainable land use. See Table 3 and Table 4 for the evaluation results and the corresponding sustainable land use degree.
Table 3 Evaluation results of urban land sustainable use in Chongqing (2000 ~ 2004)
Table 4 T coordination degree interval standard and corresponding sustainable land use degree
3 Analysis of evaluation results
The research shows that from 2000 to 2004, the degree of sustainable use of urban land in Chongqing developed from the initial sustainable use to the basic sustainable use, and then entered the stage of sustainable use, and the degree of sustainable use of urban land was accelerated. In these five years, the productivity and social acceptance of land have been slightly improved, but the stability of production and the protection of resources and environment have not changed much. The greatest contribution to improving the sustainable use of urban land is economic feasibility, which was accelerated from 2000 to 2004. The improvement of the economic feasibility of land shows that the economic value of this city's land has increased, that is, the output value of the secondary industry and the tertiary industry has increased per unit land area. Due to the development of market economy, the value of urban land itself has also been reflected. The land productivity has increased slightly, indicating that with the improvement of urbanization level, people flow, logistics and building capacity have all increased. The slight increase in social acceptability shows that people's living conditions have improved, which is the embodiment of the principle of fairness in sustainable development. At the same time, the land system has been gradually improved, and the degree of people's participation in land planning and land policy has increased. The stability of production and the protection of resources and environment have not changed much, which is a problem in the sustainable use of urban land in Chongqing. The stability of output has not changed much, which shows that the scale and structure of land use in this city have not developed in a good direction at the expected speed. Due to the large amount of land used by all walks of life, the contradiction between land supply and demand is very prominent, the city scale is unreasonable, and the land use structure needs to be optimized urgently. The protection of resources and environment has not changed much, indicating that the pressure on resources is still great, and urban environmental problems and three wastes problems need to be better solved.
In view of the problems existing in the above-mentioned urban land use process, the following measures should be taken for sustainable land use in this city in the future: ① to control the unreasonable growth of urban land, take effective measures, moderately develop peripheral groups, and change the current situation that population and industry are too concentrated in the main city; (2) Reasonably adjust the land use structure, increase the urban greening area, combine plane greening with vertical greening, and improve the ecological environment by using slopes and roofs as much as possible; ③ Take practical measures to prevent pollution and damage the ecological environment, adjust the land for large-capacity and heavily polluting enterprises in cities, and increase the land for urban pollution control facilities; Advocate the principle of "people-oriented", encourage the construction of affordable housing and low-rent housing, limit the construction of luxury houses and villas, vigorously popularize land science knowledge, enhance the awareness of land hardship, and enhance the public's awareness of participation; ⑤ Revitalize the urban stock land, raise it to the height of long-term development land, realize the change of the functional structure of the old city, improve the urban functions and realize the intensive use of land.
refer to
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[4] Liu Liming. Investigation and evaluation of land resources [M]. Beijing: China Agricultural University Press, 2005, 224 ~ 228.
[5] Li,,, Bao Haosheng, etc. PSR model and its application in the evaluation of sustainable land use [J]. Journal of Natural Resources, 2002 (5): 543