Hi, welcome to Just Answer. I will help you with your question.
There is a legal right for rainwater to be percolated away naturally by adjoining owners. Anything over and above rainwater - there is no such right.
There is an obligation upon a neighbour to take such reasonable care when doing things on his own land not to unreasonably affect his neighbour. This includes packing down the land so that rainwater can no longer percolate the substrata in the usual way.
You should therefore be able to claim nuisance as a consequence of what he has done.
Thanks for your information.
Thanks for your help. However knowing my neighbour he will ignore the information you have given me. What can I do then?