Mekedatu is around 3km from sangama, you can always drive your way to mekedatu but if you like to walk, just follow the river on the banks and you will reach mekedatu, trust me its a walk worth taking, but may be touch risky, if you are in a gang go for it, otherwise dont try, lot of people come out there just to have drinks and have a nice time, so you never know how they can turn on you.
Once you reach Mekedatu, there will be few buses in a very bad shape on the otherside of the bank, to take you to the place where the water flow narows and rips through, its just around a kilometer you can always take a walk.
Once you reach there, the first sight scares you to the core, if the water is less you can always get down and have a closer look at how water gushes through the rocks, since the river gets narower the speed of the water increses rapily and it just gushes throug the the sorounding rocks. The speed of the water does scare you, you can see holes in the rocks which are carved by the rapidly flowing river, its a sight that stuns you for a moment.
The below snap was taken when the river was running low, checkout the holes in stones, they are actually carved by the high speed of flowing water.
Food - You do get small restaurants but better pack your food before leaving if you don't want to fall sick.