Impacts Of Urbanization On Malaria In Shenzhen Based On Remote Sensing And GIS

Malaria is a serious infectious disease, which was one of the most serious infectious diseases in our country and the world. In recent years, malaria morbidity and mortality have declined at home. However, continuous urbanization makes human facing a serious threaten from virus mutation and resurgence of old epidemic. The distribution of malaria is very wide, and it can be influenced by many factors in the process of the outbreak and the transmission. Therefore, under the background of rapid urbanization in China, analysis of malaria outbreaks and changes in transmission patterns can help to carry out an era of malaria prevention and control work, and it can be helpful to study the morbidity and transmission characteristics of infectious diseases in the same kind. At the same time, it is useful in promoting the healthy development of urbanization in China. Shenzhen is located in the Pearl River Delta and has a warm, monsoon-influenced, humid subtropical climate. It is not only a representative city of China’s urbanization process but also a city of high morbidity of malaria in China. The combination of remote sensing and GIS is used to study the effects of the urbanization on malaria in Shenzhen. The content and main conclusion of this paper are as follows:(1) The comprehensive measurement of urbanization level in Shenzhen was constructed by using the composite index method. In this work, the multiple data of 30 years since the development of urbanization in Shenzhen was collected before analysis, in order to establish the index system of urbanization level of Shenzhen from four aspects of population, economy, spatial geography, and social environment. According to the principle of compound index, the comprehensive urbanization level measurement is constructed by using analytic hierarchy process. The comprehensive measure index in Shenzhen increased from 5% in 1980 to 92% 2009, which shows that the level of urbanization in Shenzhen has improved distinctly. During 1980~2000, the level of urbanization in Shenzhen was at a fast growth rate, but when it hits 50%, the speed of urbanization has gradually leveled off.(2) The land use information of Shenzhen was extracted basede on remote sensing images. According to the National land use classification standard, we established the land use classification system of Shenzhen. The object-oriented method was used to classify the Landsat TM images in the year of 1980, 1990, 2000~2010. The classification accuracy of all these years were above 80%. On the basis of the analysis, the spatial variation of the urbanization of Shenzhen is analyzed, and the land use in 2020 was predicted using Markoff model as well. From the land use transfer matrix, we found that the increase of urban area is an important factor of decrease of grassland and cultivated land area.(3) The temporal and spatial distribution characteristics of malaria in Shenzhen were studied. By analyzing the time distribution of Shenzhen, we found that the month 6-10 is the high morbidity period of malaria. The spatial analysis found that the distribution of malaria in Shenzhen may occur in all regions, but the central and western coastal areas of Baoan Distric is the high morbidity region of malaria. Meanwhile, GM(1,1) model was used to simulate and predict the time series of malaria morbidity in Shenzhen. Moreover, the temporal and spatial scan statistics were used to analyze the malaria data from 2005 to 2009, and the aggregation time and aggregation areas of the year of 2007, 2008 and 2009 was detected.(4) The relationship between urbanization and malaria in Shenzhen was analyzed. Correlation analysis showed that there was a significant negative correlation between urbanization and morbidity of malaria. The result of curve fitting analysis showed that the exponential function model had the highest fitting degree. The grey correlation analysis method was used to study the effects of various urbanization factors on malaria. The results showed that the factors of economy and space urbanization had a highest correlation with the morbidity of malaria. Through the single factor analysis of variance method, we had found that the temperature had a significant effect on the occurrence of malaria, and wetland and grassland had the most closely relationship with the occurrence of malaria.