1.The depths at the Wailanjiang Sha are liable to change,especially after a strong wind.  2.In Wailanjiang Sha,the west stream runs from 1.5h after Low Water till 1.5h after High Water and the east stream from 1.5h after High Water till 1.5h after Low Water.The maximum stream velocity is 1kn at neaps and 4kn at springs.The east stream lasts longer during the flood.