关键词: 适度指标, 土地集约利用, 指标标准化, 人口密度

Abstract:

Multi-factor comprehensive evaluation is widely used to assess intensive land use, and positive and/or negative indicators are usually employed in the evaluations. In practice, moderate indicators are exiting, which have positive effects on intensive land use within a certain value range, and negative effects when exceed the range, such as urban comprehensive volume rate, building density and population density. Moderate indicators pose a challenge to traditional multi-factor comprehensive evaluation method because the traditional method to standardize the indicators is based on a linear relationship between the original indicator values and standardization results. In this article, we propose an improved indicator standardization method based on the law of diminishing returns. This method supposes the land user as a consumer, the indicator standardization value F_i as utility and the indicator value x_i as consumption unit. Consequently, the contribution of moderate indicator to the assessment results of intensive land use follows the law of diminishing returns. The model to simulate the standardized values of moderate indicators should meet three criterion: when x≤x₀,f(x)’≥0;when x≥x₀, f(x)’≤0;f(x) is a second-order continuous and f(0)=0. Based on quadratic equation, we proposed a standardization formula: F_i=ax_i²+bx_i. This formula meets the three criterion, and the parameters a and b can be calculated by indicator ideal value x₀ and coordinate origin [0, 0]. Thereafter, a new multi-factor comprehensive model to evaluate intensive land use was built. This model combines the standardized moderate indicators derived from the improved method and the linear indicators calculated by the traditional method. Then, the population density of Chongqing was used to test and compare the improved and the traditional methods. The results show: 1) the population density of the metropolitan economic circle is greater than the ideal value 0.74×10⁴/km², and the weight of this indicator is 0.147 6. Moreover, the contribution score of population density in the intensive land use of this areas is 14.76. 2) The formula of the improved model is F_i=-1.826x_i²+2.703x_i. The improved method generated decreased value of the contribution of population density in the intensive land use of the metropolitan economic circle, compared to the traditional method. While, increased values were derived from the improved method in different degrees in other areas. 3) The evaluation results from the improved method are more objective and rational compared to the traditional method. Furthermore, the results from the improved method suggest policies more consistent with the population control strategy of the five functional districts of the Chongqing city. Although the quadratic multi-factor comprehensive evaluation model shows strength in standardizing population density of Chongqing, it needs further improvement and applications in other area.

Key words: moderate indicator, intensive land use, indicator standardization, population density