东非国家小城镇形成与发展的潜力——基于最大熵模型分析

Town formation and development potential of East African countries based on maximum entropy model

21世纪以来,小城镇已成为东非快速城市化的重点区域。论文对坦桑尼亚、乌干达2个东非典型国家的城市进行了等级划分与数量统计,确定以10万人以下的城镇、小城市为研究对象。选取7个自然环境变量与6个社会经济变量,结合城市数据,构建最大熵模型。利用模型得到的平均生境适宜性指数(HSI)判别小城镇形成适宜度、划分潜力区,并与人口密度进行对比分析。研究发现:①距区域性主要交通干线距离、距全国性主要交通干线距离、归一化植被指数(NDVI)与距大城市距离对两国城镇、小城市的贡献率均较高;不同国家不同规模城市有其特有的高贡献率变量。②随城市规模增大,交通干线贡献率下降,自然环境变量贡献率上升。③坦桑尼亚北部HSI值整体高于南部,HSI高值区城镇呈团块状,小城市呈条带状。乌干达全境HSI较低,HSI高值区城镇以坎帕拉为起点呈放射网状,小城市为碎片状。两国HSI高值区基本位于路网、河流湖泊附近。④坦桑尼亚人口密度普遍小于乌干达,潜力区总面积则大于乌干达。潜力区与人口密度关系主要分为3种:比周边人口密度大,为历史悠久、经济实力强、靠近大中城市地区;与周边人口密度相近,为快速发展中的地区;比周边人口密度小,为区位条件优越地区。研究结果填补了资料稀缺的东非地区小城镇研究不足,可为东非国家未来城市建设及中方与东非的投资合作提供建议。

Since the twenty-first century,small towns have become a key region of rapid urbanization in East Africa.In this study,the cities of two typical East African countries—Tanzania and Uganda—were classified and towns and small cities with less than 100000 people were identified as the research regions.Seven natural environment variables and six socioeconomic variables were selected and combined with urban data to construct a maximum entropy model.The average habitat suitability index(HSI)obtained from the model was used to discern the suitability of small town formation,classify the potential areas for development,and compare and analyze them with population density.It was found that:1)Distance from regional major traffic arteries,distance from national major traffic arteries,normalized difference vegetation index(NDVI),and distance from large cities all have high contribution rates to town and small city development in the two countries;each country has its own high contribution variables specific to cities of different sizes.2)As the size of cities increases,the contribution rate of traffic arteries decreases and the contribution rate of natural environment variables increases.3)The HSI values in northern Tanzania are higher than those in the south overall.The towns in the high HSI area are clustered,and distribution of the small cities is in stripes.In Uganda,the HSI values are lower in the whole country,and the towns in the high HSI area are in a radial network distribution starting from Kampala,while the distribution of small cities is in a fragmented shape.The HSI high value areas in both countries are basically located near road networks and rivers and lakes.4)Population density of Tanzania is generally lower than that of Uganda,while the total area of its potential development areas is larger than that of Uganda.The relationship between potential development areas and population density is divided into three main types:(1)larger than the surrounding area's population density,for areas with a long history,strong economic power,and close to large and medium-sized cities;(2)similar to the surrounding area's population density,for areas under rapid development;and(3)smaller than the surrounding area's population density,for areas with superior location conditions.These results fill the research gap of small towns in East Africa where information is scarce,and provide references for future urban construction in East African countries and investment cooperation between China and East Africa.