You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "where is the mouth of the river severn and what is it called?" whose answer is Severn Estuary.
Each document should contain about 30 words, and these documents should contain useful information.

Query: mouth of river severn
Useful Output:

Doc 1: Here is my complete flyby of the River Severn. Starting in the Plynlimon hills, travelling through Caersws, Newtown and Worcester,
Doc 2: River Severn Source to Mouth (OS Open Rivers)
Doc 3: Discover Britain's longest river, the Severn, starting in the Cambrian mountains with its meandering tributaries and the famous Severn Bore wave at its mouth.
Doc 4: It flows from the moorlands of central Wales, generally southeastward through England to its Irish Sea mouth in the Severn Estuary. It is
Doc 5: Find the perfect mouth of river severn stock photo, image, vector, illustration or 360 image. Available for both RF and RM licensing.