North China. The boundaries of its jurisdiction are adjacent to Lianyungang and Suqian in east; Suzhou of Anhui province to the south; Huaibei to the west; Linyi, Zaozhuang, Jining and Heze of Shandong province to the north. The area can be divided into four sectors from east to west, constitute the Shandong–Jiangsu Traps (), the Tancheng–Lujiang Fault Zone (), the Xu–Huai Downwarp-fold Belt () and the Fault-block of West Shandong () respectively. Most of the area is located in the Xu-Huai Alluvial Plain, the southeast part of the North China Plain. The confluence of the former Si River and the former Bian Canal, situated off the ancient Xuzhou city north-eastwards. The city and its hinterland were the areas liable to severe flooding by the Yellow River since the tenth century. In 1194, the river changed its course to join the Si River, the former tributary of the Huai. From then on, it flowed along the north of the walled city until 1855. The city proper is bisected by its ancient course nowadays, while the Yunlong Lake () is located in the southwest. North of the lake is Yunlong Park. Climate Xuzhou has a monsoon-influenced humid subtropical climate (Köppen Cwa), with cool, dry winters, warm springs, long, hot and humid summers, and crisp autumns. The monthly daily average temperature ranges from in January to in July; the annual mean is . Snow may occur during winter, though rarely heavily. Precipitation is light in winter, and a majority of the annual total of occurs from June thru August. With monthly percent possible sunshine ranging from 44% in July to 54% in three months, the city receives 2,221 hours of bright sunshine annually. The lowest temperature recorded in Xuzhou was , on 6 February 1969, while the highest was , on 15 July 1955. Demographics According to the 1% National Population Sample Survey in 2015, the total resident population of Xuzhou reached 8.66 million, and the sex ratio was 101.40 males to 100 females. Economy Historically, Xuzhou and the surrounding regions were a predominantly agricultural area. Its arable land was severely depleted by the changes in the course of the Yellow River since the mid 11th century, and the drought-resistant crops: wheat, sorghum, soybean, maize and potato, became the local staples. Besides, cotton, peanut, tobacco and sesame also grew in low-yield. The local mining traces it origins to an iron mine, Liguo. It