Narrower and more turbulent sections of water in the upstream parts of the Mekong River, coupled with large annual water level variations continue to present a challenge to navigation. The seasonal variations in water level directly affect trade in this section of the river. Volumes of trade being shipped decrease by more than 50%, primarily due to the reduced draughts available during the low water season (June–January). Despite these difficulties, the Mekong River is already an important link in the transit chain between Kunming and Bangkok with about 300,000 tonnes of goods shipped via this route each year. The volume of this trade is expected to increase by 8–11% per year. Port infrastructure is being expanded to accommodate the expected growth in traffic, with new facilities planned for Chiang Saen port.