Is Canal Made For Drainage Or For Garbage?

Drainage is one of the major problems in a highly populated place in my country. In order to solve the problem, the local government made small canals that would serve as water drainage. But, is making canals is the solution to the problem? Well, based on my personal observation and experience, yes it is a short term solution. Why short term? Because it is only good for a newly made canal. As time goes by, canals will overflow at wet season due to the garbage that had been thrown by undisciplined people. As far as I know, the main problem here is not the drainage system, but it were the people discipline. No matter how many canals made, no matter how many ordinances being implemented, but if the people' has no discipline, making of canals is not effective at all. It may lead you to ask, if it is for drainage or for garbage?