When a stream leaves an area that is relatively steep and enters one that is almost entirely flat, this is called an alluvial fan. It is shaped like the letter E, and to fully understand what an alluvial fan is, you have to understand how streams work.
Also known as anastomosing,. Usually found close to very high mountains, braided streams have multiple channels that continuously branch and join along the entire length of the stream, which in turn creates numerous longitudinal bars between the channels.
Deltas result when streams enter a standing body of water, usually an ocean. Deltas are like alluvial fans in one aspect because there are distributary channels which spread out from a single channel.