| Yangtze River Delta region is China’s largest economic zone, the densely populated, economically developed, fragile ecological environment, natural disasters, facing the pressure on the environment, natural disasters and climate change risk increases with each passing day, flood, typhoon and storm surge disaster is very serious. It is the high-risk area in China. Population, as an important carrier, is the main object in disaster risk management and climate change adaptation. Population data is based on census data and it reflects the whole administrative unit, poor commonality of data, and natural geographical unit spatial mismatch, not conducive to and multi-source data fusion using. Existing gridded population data is global scale, national scale. Their spatial resolution and precision are not suited when we use them to study the population distribution characteristic analysis in region. Establishing a regional scale grid population data, which can truly describe population spatial distribution, reflect the actual population spatial distribution, provides more accurate population distribution data when used to social, political and economic analysis.Using ArcGIS software, basing on demographic data, administrative data, land use data, DEM data, road data, network, schools, hospitals distributing data and using multiple regression model, we simulate the population distribution of the Yangtze River Delta. Then we analyzed the population spatial distribution pattern of Yangtze River Delta coastal lowlands with 200 m * 200 m grid population data. The results are as follows:(1) Established a 200 m * 200 m grid population data in Yangtze River delta. We calculated the land use type of area ratio, average elevation, average altitude, roads, rivers, school mean impact value of population distribution influence factor to establish the geographical factor database of district administrative level. Using ArcGIS to create 200 m * 200 m grid vector data, Then we select higher coefficient impact factor of population distribution, respectively is terrain, rivers, highways, urban land index, rural index, index of cultivated land, woodland index, hospital and school level, establishing grid geographical factor database. According to the population agglomeration degree classification, the study was divided into 10 blocks, and the correlation analysis was carried out, and the factor model was selected by stepwise regression method. After grid computing, merging blocks, we obtain the 200 m * 200 m grid population data.(2) Analyzed the spatial distribution of population in Yangtze River delta. The population distribution is uneven, the formation of hot and cold areas of population distribution. High population density zones, which are mainly concentrated in Jinqu basin area of Shanghai City, Northern Zhejiang Hangjiahu Plain, along the coast of Hangzhou Bay area, Zhejiang southeast coastal areas, Zhejiang Hilly Basin, Jiangsu, Nanjing, Suzhou, Wuxi, Changzhou and other southern and the northern city of Xuzhou City, Jiangsu most of the northeastern region with less population, in the mountains of southern Zhejiang, the population of the Northwest Territories populated, forming cold spots. Shanghai Laoximen is the highest population density value area of 101725 /km2, the average population density is 675 /km2 in Yangtze River delta.(3) Defined the Yangtze River Delta coastal lowlands. The Yangtze River Delta coastal lowland distribution is within the distance from the coast of 180 km, accounting for 32.2% of the total area of administrative region is within the range of 60 km. A total of 1327 streets(township), area of 70051km2, accounted for 33.5% of the Yangtze River Delta provinces, the Jiangsu coastal lowlands area is the largest, 58731km2, accounting for 58.19% of total Province. The contribution rate is also the largest. 37.7% of the area is below 4 m and 4 m, 87.2% of the area is in 3-7 m, 61% of the area within 60 km from the coastline, the largest area to 13.89% of the total area is within 10 km distance from the coast line. With the distance from the coastline increasing, the lowland area decreased.(4) Analyzed the spatial distribution characteristics of the coastal lowland population in the Yangtze River Delta.The low population of the Yangtze River Delta is not evenly distributed, and there is a huge space difference in population density. Population density is greater than 30000 people / km2 in regions of high density, when 8.94% of the population is concentrated in the land of 0.16%. Population density 3000 people / km2 area only accounted for 4.58% population but accounted for 49.06% of the total population. The population is highly concentrated in a small area. 87.84% of the area population is less than 1000 people /km2, the population accounts for 32.25%. The population is highly concentrated in the small area.In 2010, Jiangsu, Shanghai and Zhejiang Province coastal lowland population accounted for 56.24% of the total population in Jiangsu Province, 97.09% in Shanghai, 10.62% in Zhejiang. The coastal lowland population is huge, about 1/2 of the total population of the Yangtze River Delta. 87.84% of the area population is less than 1000 people /km2, population accounted for 32.25%. The Yangtze River Delta coastal lowlands in nearly 70% of the population is concentrated in the altitude of 3-7 m region. There is nine percent of the population distribution at an altitude below 7 m. 29.3% of the population concentrated within 20 km, more than 60% population distributes in the distance from the coastline within 60 km; 80% of the population distributes in the distance from the coast line is less than 90 km.Yangtze River Delta coastal lowland population density high value area is located at an altitude of 0-4m and population density were more than 10000 people / km2 and to 3m regional population density maximum value and achieve 32055 people / km2. With the altitude increasing, the population density decreased and stabilized. And in the 30 km of distance from the coastline of population density larger and at a distance of a coastline of 10-20 km within the region the average population density is the largest regional to 25776 people / km2.Away from the coastline 160-170 km region, population density appears a small high peak(12575 people / km2). Population density of the island is large, Zhoushan city as the main gathering area of the population.The comparison of Landscan 2010, GPW V3 2010 and 200 grid data shows that the landscan statistics the total population of at least, then GPW V3 2010, and 200 m grid data calculated the maximum. A total population calculated by GPWv3 and LandScan are lower than the census data. The spatial distribution of population is difficult to obtain the real situation, because of the lack of verification and evaluation technology, precision and population spatial assessment is still a challenging problem. |
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