Heat Island Intensity Reduction-oriented Urban-rural Built-up Area Dynamic Simulation And Spatial Governance Path Research

China is experiencing rapid urbanization in recent decades,which is manifested by the rapid expansion of built-up area.However,this excessively extensive urban growth has brought about a series of natural environmental and social problems while promoting the rapid development of the economy,among which the urban heat island(UHI)effect is the most obvious one.The UHI refers to the phenomenon that the temperature in the urban areas is higher than that in rural areas,which has been observed in the most cities in the world.The UHI effect destroys the ecological environment of cities,improves the energy consumption of cooling facilities,and even poses threats to human health.One the one hand,the mega-city,such as Beijing,has planned the strategies to reduce the size of built-up area and to optimize the layout of built-up area undering the guidance of the new urbanization strategy and construction of ecological civilization,and put forward new requirements for the dynamic reduction of built-up area.On the other hand,the increasingly serious UHI effect is gradually threatening the productions and residential lifes.These is an urgent need for scientific guidelines to alleviate the UHI effect.This paper organically combines the UHI mitigation with the dynamic reduction of built-up areas under this background,which can be used to reveal the response mechanism of UHI to land use/cover change(LUCC).Then this paper delineats the dynamic reduction of built-up areas to achieve the goal of UHI mitigation and urban structure optimization,and form a systematic spatial governance path for dynamic reduction of built-up areas(including new built-up areas and built-up area reduction)for UHI mitigation.It has significant theoretical guidance and practical value for China's layout of built-up area under the sustainable development theory to achieve the strategic goals of optimization of built-up layout and UHI mitigation.This paper first exhibited the research background and significances of this research.Subsequently,based on the “driving force-pressure-state-impact-response” analysis framework,the core issues of the study were analyzed,and the interaction between urban land use changes and thermal environment changes was expressed from three methods.Taking the key areas of Beijing as an example,the process of land use/cover change in Beijing was analyzed with the help of Google Earth Engine platform and machine learning algorithm,and the fundamental driving force of past LUCC was urban expansion and economic development.We then used data fusion method to obtain the spatiotemporal pattrens of UHI effect in last 16 years.Furthermore,we utilzed the regression method to study the response mechanism of heat island effect to land use/cover change.Three scenarios were set up to carry out a simulation of dynamic reduction of construction land for UHI mitigation.Finally,the new built-up and built-up reduction area with the goal of reducing the intensity of the heat island were delineated,and the "object-factor-management-control" space governance path was proposed to form a monitorable,controllable and adjustable space Governance system.The main conclusions of the paper are as follows:(1)Expansion of construction land is mostly at the expense of arable land occupation and reduction of unused land.Specifically,the construction land in the study area expanded rapidly from 1994 to 2018,with the growth rate gradually increasing from 1994 to 2012 and decreasing from 2012 to 2018.The expansion mode has changed from the previous filling and marginal expansion to marginal expansion and jump expansion.In general,built-up area expansion is still carried out in a "spreading pie" manner.In addition,the main expansion directions of construction land are northeast,east and southeast,while the west is expanding very slowly.Qualitative analysis results show that the demand for economic development is the fundamental driving force for LUCC.(2)LUCC is the main influencing factor of UHI intensity change.Firstly,the use of data fusion model provides an accurate algorithm for generating long-time high spatial resolution of land surface temperature(LST).The study of the spatiotemporal patterns of the UHI shows that the intensity of the heat island in the central area of Beijing has showed a decreasing trend from 2003 to 2018,while the intensity of the heat island in the surrounding area has showed an increasing trend.The results of spatial clustering analysis show that the heat island intensity in the central area belongs to the high value area,while the heat island intensity in the surrounding area belongs to the low value area.Subsequent research on the response mechanism of LST to LUCC shows that land use/cover change is the main driving factor of UHI intensity change.(3)The degree of mitigation of heat islands in different scenarios in 2035 based on 16-year LST data is significantly different.The distribution of construction land under the three scenarios in 2035 is more concentrated and continuous than in 2018.The reason is that the built-up reduction areas is mostly located in scattered rural settlements and rural industrial and mining land in the outer suburbs,while the new built-up is mostly located on the edge of the existing built-up area.In terms of the heat island mitigation effect,the sprawling development scenario(Scenario 3)has the highest heat island reduction effect,followed by the planning-oriented development scenario(Scenario 1),and the compact development scenario(Scenario 2)has the least effect of heat island reduction.(4)Based on the results of scenario simulations,construct the “object-factorcontrol” spatial governance path.First,we zone the new built-up area and built-up reduction area.Then,the spatial configuration mode of different elements in each area is clarified.Multiple governance subjects are launched to jointly participate in the spatial management and control of the dynamic reduction of built-up area for heat island mitigation.This procedure can achieve the “monitoring-evaultion-forecast-adjustment” dynamic governace management mechanism to form a space governace system that can be monitored,controlled,and adjusted.