Changes to rivers and streams can happen naturally, but has increased over the years due to which kind of human activity?

The modifications in the streams and rivers have taken place naturally, however, because of the human interferences it has augmented in an uneven manner. There can be various reasons related to it, but the most important would be the development of the dam and the redirection of the flow of water.  

There are various modifications done when the building of the dam is done, at certain times the natural direction of the flow of water is changed and thus, it leads to modifications in the streams and rivers.  

what following? you said which of the following. but there is no be more specific.

the answer for apex is "1 and 6"