The region between North Harbor at Wai'ao Village of Toucheng and Beifang'ao of Su'ao is called the Lanyang Alluvial Fan Coast. The ocean scenery is rather dull here. In addition to the heavy sand sediment in the rivers, the strong northeasterly monsoon winds are a defining force on the formation of this region. For example, the sand spit at the mouth of the Lanyang River is generally known as a sandbank which is levee-shaped sand sediment accumulated offshore as a result of waves and ocean currents. Along the inside of the entire coastline and under the monsoon winds there has accumulated an approximately 15- to 20- meter-high sand ridge that is steep on the east slope and gentle on the west side. The ridge hampers drainage on the plains and causes the wetlands in places including Zhu'an, Wushierjia, and Wuwei Harbor to flood after heavy rainfall or a typhoon.