ZHANG Lin

Abstract：Urban land resource is a kind of scarce resource， whether the land supply can be effective will directly affect the development of the city. Shenzhen， one of China's largest cities， has a population of more than 10 million， but an average annual land supply of less than 50km2.This paper analyzes the land supply data of Shenzhen （2010-2019） by SPSS， summarizes the characteristics and shortages of land supply in Shenzhen by using GIS system， and predicts the total land area of Shenzhen in 2025.The results show that there are defects in the land supply control measures in Shenzhen and the actual annual land supply plan cannot reach the expected planned quantity; In recent years， the development of urban space mainly extends to the northeast and the west; There is a lack of coordination of land supply from year to year， the land supply fluctuates greatly， and the adjustment of the internal structure of all kinds of land has not appeared in recent years. By establishing a mathematical model， it is predicted that the total land area of Shenzhen will reach 1，049.68 km in 2025. For Shenzhen， the future land use situation will be severe and the space expansion will be under great pressure.

Keywords： Land Supply; Land Policy; GIS

1.Introduction

Sustainable and effective supply of land resources is the foundation of urban development， full and reasonable utilization of land resources is also a powerful driving force of economic development. However， the land supply mode adopted in China in recent years makes land supply decouple from urban planning， and urban planning can't be realized through land supply regulation. The root of this problem is the unreasonable distribution of land resources in the supply of land. To achieve the rational distribution and utilization of land resources， it is necessary for governments to perfect the urban land supply mechanism， strengthen the management of urban land supply， respect the law of the market， give full play to the role of the market mechanism， rationally determine the supply and reserve of various types of residential land， and realize the scientific and reasonable supply of urban land in a planned way. For Shenzhen， it needs more planning intervention and guidance in advance in the supply of construction land， to guide the orderly construction of Shenzhen city， reasonably shape the urban space， highlight the urban characteristics， and avoid homogeneous development with other cities.

2.Forecast of Land Supply Scale in Shenzhen

It is found that there is a linear relationship between GDP， fixed asset investment， the population and the scale of construction land， and they can be used as the dominant factor affecting the scale of construction land. Therefore， this study uses multiple linear regression to establish a prediction model between the scale of construction land in Shenzhen and social-economic impact factors.

Y = B0 + B1X1 + B2X2 + B3X3

In the formula， Y represents the scale of construction land in the urban area of Shenzhen， X represents the dominant factor affecting the scale of construction land， and B represents the coefficient of each impact factor.

Make：

X1—GDP

X2—Fixed Asset Investment

X3—The Population

The 2010-2019 Shenzhen urban construction land area， GDP， fixed asset investment and population are statistically sorted， and the constant B0 and coefficients B1， B2， B3 are estimated and tested.

Using the above data， a multiple linear regression equation is established by SPSS software， and the equation is obtained as follows：

Y= 0.156X1-0.247X2 + 0.084X3 + 678.469

Using regression coefficient significance test， R2 = 0.999， significance = 0.000， less than 0.005， indicating that the fitting degree is high， the model is reliable and can be used to predict the construction land scale of Shenzhen in 2025.

By substituting the predicted GDP， fixed asset investment and population into the multiple linear regression equation， the construction land scale in an urban area of Shenzhen city in 2025 will be 1049.68 km2.

3.Conclusion

In terms of land supply characteristics：

1. The scale of land supply， there are the following problems： There are defects in the land supply control measures， the actual annual land supply plan cannot reach the expected plan; The construction area is close to the upper limit of the planning target， and the problem of limited construction land scale will always exist; The supply of residential land in Shenzhen is reducing year by year， and the ratio of industrial land and commercial land is too high.

2. In terms of the spatial distribution of land supply， the land supply in Shenzhen is not well-coordinated with the planning， resulting in urban development that cannot be fully developed as planned; The eastward direction differs greatly from the westward and northeastward direction in terms of the number and scale of land supply cases; The land use situation in Shenzhen is grim， and the pressure on space expansion is large. For example， the scale of new construction land used in 2009-2020 is 58.31km2， with an average of fewer than 5 km2 per year.

3. The timing of land supply is mainly manifested in the lack of coordination of land supply during the year; There is large fluctuations in land supply; The adjustment of the internal structure of various types of land in recent years has not appeared

Land supply control strategy：

The land supply scale， through the establishment of a mathematical model， it is forecasted that the total land area of Shenzhen will reach 1049.68km2 in 2025， exceeding the land load limit of Shenzhen. Therefore， the urgent task of Shenzhen is to digest the required land in the existing land by adjusting the land type and urban renewal.