This can be explained in accordance with the General Relativity theory of Einstein's which says that the time dilation depends directly on the intensity of gravitational field (for an observer outside the field).
So, as the intensity of the field increases so does the time dilation.
The black hole has highly intensified gravitational field and as such the time dilation near the boundary of the black hole also increases immensely and stops at the event horizon.
Thus the gravity of a black hole is sufficient enough to slow down a clock as one gets nearer to it.
The only thing I can think of is that they are both relatively detached from the rest of the world. They both rely a lot on their own resources. Isolationist to a certain degree.
Answer:River restoration immediately benefits the quality of the ecosystem through re-engineering channels that improve the ecology and reduce floods. It also enhances biodiversity in the area by restoring natural functions. Rivers are important natural habitats for different plants and animals