I modeled a castle below based on Chateau de Chenonceau. Now I wanted to create flowing water for it to stand in.
I started by creating a polygon plane where I want the water surface to be, and applied an OceanShader material to it. (Right click –> Assign New Material.. –> Ocean Shader)
The default ocean texture looked like this:
The size of the waves were too large, so I increased the Scale (under Ocean Attributes in the attributes editor) to 3.
This made the water surface look like this:
The default colour was too bright, so I made the Water Color (under Common Material Attributes in the attributes editor) darker.
To make it look more realistic, I added a Noise node to Water Color. (Click on Water Color  in attributes editor –> Select Noise)
In the Noise attributes editor, under Color Balance, I adjusted the Default Color, Color Gain, and Color Offset.
This made the water surface look a bit more realistic with colour variance imitating shadows and depth.
It still looked a bit bright though, so back in the Ocean Shader attributes editor, I reduced the Diffuse to 0.
Now for animating the water. In the Ocean Shader‘s attributes editor, under Ocean Attributes tab, there is Time.
To make the water surface flow continuously, I put an expression in that Time slot (rather than keying values and animate it using the timeline or graph editor).
I tried it out by typing “=time” in the Time slot. This made the wave too fast for what I wanted. I decreased the Time by replacing the expression with “=time/2”.
Below is how the animated water turned out. Try to view it in HD to see the details.