If you are planning to make a garden pond to your garden you can use several items.
Dig the hole and put a liner or a plastik ready made pond. If you use a membrane liner then to protect it you should use a nonwoven filter.
Select some stones and pebbles for the slopes or use a three dimensional mat to protect sliding the soil or stones inside the pond.
You can use a product called Enkamat or similar.
This products holds the particals and if some plants start to grow through it it will protect the slopes.