Children play by a canal and a Baja, 3 wheeled taxi. There are 13 larger rivers that flow through the Jakarta. 18 main canals and 500 smaller canals. The canals were built by the Dutch two centuries ago to control flooding by channelling excess water back into the sea. In the rainy season they come under massive pressure because of the amount of water a rubbish, which builds up and blocks the flow of water.