Quantitative Analysis And Scenario Simulation Of Urban Heat Island Effect Coupled With Land Use Change In Wuhan, China

The level of urbanization is an important indicator for measuring the economic,cultural and technological development of both a country and a region,and the Urban Heat Island(UHI)effect is a typical urban climate phenomenon accompanied with the emergence of urbanization.Due to the urbanization,the accompanying expansion of impervious surface greatly affects the thermal properties of the underlying surface.As one of the most representative landscape signs reflecting the alteration of surface,land use/cover change is closely related to UHI.Therefore,exploring and analyzing the intrinsic relationship between UHI and urban land use change helps to reveal the formation as well as evolution mechanism of UHI.At present,the existing studies on the relationship between UHI and urban land use change are usually based on qualitative analysis,and lack quantitative models to determine the mathematical relationship between the two.On this basis,with the support of RS and GIS technology,this paper aims to analyze the temporal and spatial evolution characteristics of UHI from 2005 to 2015 in Wuhan,China.In addition,a new indicator called LCI(Land Contribution Index)is proposed and constructed for better quantifying the degree of contribution of each land use type to UHI.And based on the CA-Monte Carlo model,a scenario simulation of UHI coupled with land use plannnig is operated,from the results of which,countermeasures for the current status of UHI in Wuhan are proposed.The main work of this paper is as follows:(1)The spatial and temporal evolution characteristics of UHI in Wuhan were discussed.The result shows that,the UHI effect of the study area has been expanding from 2005 to 2015.In 2015,the area of strong heat island(including the UHI intensity levels of high and extremely high)accounted for 8.56% of the total urban area,twice as much as in 2005(3.35%).The early strong heat island was mainly distributed along the Yangtze River in Wuhan with a small scale,and then it radiated and spread to the surrounding area;while the weak heat island scattering in southwestern part of the city transformed into moderate or even stronger heat island.Moreover,in the second half of the research cycle,the proportion of the increasing UHI zone decreased from 31% to 17%,indicating that although the UHI effect in Wuhan is overall enhancing,its temporal and spatial characteristic has experienced an “intense first,then stable” process.(2)A model of the relationship between UHI and land use change was constructed according to LCI index.The result presents that,the respective thermal contribution of five land use types to UHI ranks as follows: construction land > unused land > 0 > agricultural land > forest land > water body.Construction land is the main land use type causing the aggravation of UHI,while the water body can suppress the UHI to the utmost extent.Due to the decrease of solar radiation in winter,the dropping vitality of each land use type results in the weakening of contribution to UHI compared with other seasons.(3)The scenario simulation of UHI coupled with land use planning was carried out.Taking UHI into consideration,the simulation determines the land use planning scenarios that meet the strategic objectives of the “General Land Use Plan of Wuhan City(2006~2020)”.The rationality of the three UHI simulated results under three land use planning scenarios is ranked as: Scenario ?>Scenario?>Scenario?.In Scenario ?,the intensity of UHI is relatively low in 2020,the area of construction land approaches the target in the Plan,and the holding amount of agricultural land has not crossed the “Red Line” in Wuhan.Such scenario is a state that conforms to the control of urban planning,and it is also the most suitable planning scenario for the sustainable development of urban ecological environment.(4)Aiming at the practical circumstance of Wuhan,methods and measures to alleviate the UHI are proposed.By optimizing the spatial distribution of land use,clarifying the protection of cultivated land and basic farmland,making intensive use of construction land,and by enhancing urban greenings,increasing forest area,as well as protecting urban low-temperature corridors such as water bodies and mountains,all contribute to improving urban thermal environment.