Why Contours Matter

Here is a clear example of why it is vital to know your contours and not just put a gate where the fencing wire runs out.
For hundreds of years this hill was a Maori Pa, the food was grown on carefully levelled contour beds lined with clay.
Lately the area was fenced off.  You can see here the gate has caused people to walk off contour, and this small change has created a source of erosion.

The path drops to meet the gate, and so does rainwater. Then the rainwater continues to run downhill eroding all the fence posts.