River systems of Thailand divides into two major branches, the " Tiền Giang" (Front River) and "Hậu Giang" (Back River). These in turn enter the South China Sea through nine estuaries. The following are the principal tributaries of Mekong River which flow through Thailand (tributaries entirely outside the Thai border not shown). The Mekong drains a considerable portion of northeast Thailand. In terms of Thai territory drained, it is second only to the Chao Phraya system. The Salawin River rises in Tibet (Tibetan: རྒྱལ་མོ་རྔུལ་ཆུ།) after which it flows through Yunnan, where it is known as the "Nujiang" River (), although either name can be
Tapi River, Thailand Tapi River, Thailand The Tapi (or Tapee) river (, , ) is the longest river in southern Thailand. The river originates at Khao Luang mountain in Nakhon Si Thammarat Province, and empties into the Gulf of Thailand at Bandon Bay near the town of Surat Thani. It has a length of . The river drains an area of and in 1997 had a yearly discharge of or per year. The Phum Duang River (or Khiri Rat River), which drains another west of the Tapi watershed, joins the estuary west of Surat Thani in Amphoe Phunphin. The river was named on