Aerial photos can be used to help identify river features. For example, geographers might be able to view the different courses, or they might be able to identify some of the main features and landforms such as waterfalls, levees, or meanders.
The image shows the river valley at the mouth of the Glenariff river. The meandering path of the river can just about be seen across the flat green section in the middle of the photograph.
The flat river flood plain is very obvious as is the high land that surrounds the river valley. Higher land in the Antrim hills will often have less vegetation and be a brown colour. The dark green areas towards the bottom left of the map indicate some planted forest.
It is possible that you might have to identify river features directly from an aerial photo or a satellite image but it is more likely that you will have to match this up with what you can see on an Ordnance Survey map.