To exploit one's specific position, authority, or circumstances to advance oneself or gain personal benefits.

他在采购部门工作，就开始利用职权谋取私利，真是靠山吃山，靠水吃水。

To make use of local resources or adapt to one's environment to make a living; to live off the land.

这里的人们靠山吃山，靠水吃水，过着自给自足的生活。