Water crossing can be pretty dangerous, the strength of the water pushing against the car can wash it off the road or crossing. This can be dangerous, however a few hints may help you cross water safely, but beware if you are worried do not cross the river or water. See video. Advice given by James Gorrie, he has over twenty (20) years driving to remote parts of the NT Have a look at driving history
Great video for water crossing.
Driving on wet roads is normal in the wet season and the roads can become water crossings. Learn how to drive across water in 4WD course in Darwin
Darwin can get very wet have a look at slippery dirt roads in Darwin