Xiao Yun is surrounded by mountains and faces the sea, and its terrain inclines from northwest to southeast. Land area 1050.75 square kilometers, low mountains account for 13%, hills account for 49%, plains account for 28%, and fresh water accounts for 10%, which belongs to the combination zone of hills, terraces and low mountains. The main stream of Zhangjiang (commonly known as Beixi) originates from Dafeng Mountain in Pinghe County and enters from the north of the county, with a total length of 67.8 kilometers, a domestic flow of 58.2 kilometers and a domestic drainage area of 862.3 square kilometers. The east, north and west rivers flow into the inland sea of Zhangjiang Bay; Rivers in the southeast flow into the inland sea of Dongshan Bay; Guanyangxi in the southwest flows into Zhaoan County and into the sea. There are 0/3 rivers in the county, with a total length of 225.7 kilometers. There is Fengtou Reservoir in the northwest with a storage capacity of 65,438+77 million cubic meters. There are 7 peaks above 1000 meters, of which 6 are the highest peaks at the junction of Zhangpu, Zhao 'an and Pinghe, and Xishan source (the main peak of Wushan mountain range), with an altitude of117 meters. It belongs to a typical subtropical maritime monsoon climate, with an annual average temperature of 265,438 0.3℃, a frost-free period of 347.4 days, a rainfall of 65,438 0.730.6 mm, mild climate, spring-like seasons and abundant wildlife, water and Chinese herbal medicine resources. This stratum contains a large number of minerals, such as granite, kaolin, crystal, alum, lead, zinc, gold and silver. The natural mangrove community in Zhangjiang Estuary breeds and inhabits 150 kinds of rare birds. It is a national mangrove nature reserve with the highest latitude, the largest area and the most species in China and an internationally important wetland. The county's coastline is 75.5 kilometers long and the sea area is 106.7 square kilometers. Large and small islands 12, and the larger bays are Zhangjiang Bay and Dongshan Bay.