Hi I have a property in Ipswich QLD and the soil in the back is slowly eroding away. The house behind ours has a trench dug out on their side of the fence (was there 15+ years ago) with large pipes allowing water to go somewhere towards the front of the property. This is slowly causing the soil to erode as the water runs into this trench (sloping land) taking away dirt with it. You can also see more of the concrete that supports the fence posts.
I have contacted them about this over the years but they have not done anything to rectify this (e.g. build a retaining wall on their side).
What can I do about this? The gap under the fence is over 30cm in some places. Is it my responsibility to build a small retaining to stop the erosion, or should they? Or am I being unreasonable?