Khlong Cha-Un (คลองชะอุ่น) is a subdistrict of Phanom in Surat Thani. The municipality describes plains surrounded by hills and headwater forest towards the eastern and western sides.
Water storage has particular local importance. The municipal plan identifies the Khlong Bang Sai Nuan reservoir at Ban Thap Khrist, while the Royal Development Projects Board documents a separate project for Ban Bang Hin in Village 5. Its account places that village on foothill ground between western hills and Khlong Cha-Un. These are specific community and irrigation locations within the wider tambon.
