Obviously you're bound to get a some different ideas here, but I'll give it a shot.Please help me.
1. how do you write the sound of the dog, when he's barking? wuf wuf?
2. how do you write the sound of spray of dust/sand?
3. how do you write the sound of ground hit by a log?
4. how do you write the sound of bushes hit by a branch?
The only one that really has a pretty standard range of answers in the first one:
1. A dog barking? Woof woof / bow wow / arf arf are three that are used on a fairly routine basis.
(Also, in the U.S. it's more often spelled woof. I have seen wuf, though.)
2. The spray of sand or dust? Now there's an onomatopoetic challenge. All I can think of is swoosh or whoosh or something like that, and those aren't very imaginative. I'm drawing a blank here.
3. The ground hit by a log? Piece of cake: thump or whump.
4. Bushes hit by a branch? Rustling comes to mind. Can't think of anything better.
Actually, the possible contexts associated with #2 and #4 could vary, and that makes it a little tougher. For example, it's difficult for me imagine a context in which dust could make any sound at all. And as for the sand, is it being blown against the side of something? That would make a big difference. The bushes and the branch: do you mean like a branch falling on top of or into some bushes? A bit unclear. Not that that would help me give you anything better, but sharpening the mental image is likely to help others more creative than me.