These are the Ryde Falls near Oxford which is about an hour north of Christchurch. It’s about a 2.5 hour walk along an easy track (with a few stream crossings!) to get into the falls. It’s a lovely bush track with more bell birds singing away than I think I have seen anywhere! And lots of fantails following you along the track as well. If you are looking for a half day walk not far from Christchurch, I would highly recommend it.
For more information check out the New Zealand Tramper website at http://tramper.co.nz/?2304