(fig.) gulf; chasm; wide gap / (originally) the Hong Canal in Henan, which in ancient times formed the border between enemies Chu 楚[Chu3] and Han 漢|汉[Han4]
鸿
=
江
+
鸟
:
Helga Horse (hu) is going to kill and eat a turkey (鸟) in the engine's kitchen ((e)ng2) when suddenly a huge river (江) forms and an eastern bean goose (鸿) floats by to rescue the turkey.
沟
=
勾
+
氵
:
In front of the outhouse (ou1) Guy Fawkes (g) drew (勾) a photo-realistic comic (勾) of an open gully (沟) on the floor. The people are afraid to step onto it because it looks so real. They only start to believe Guy Fawkes that it's not as he spills a bottle of water (氵) over his chalk painting.