Branching appears wherever a flow has to distribute itself over an area with a limited amount of energy: in river deltas, in lightning, in leaf veins, in blood vessels. The geometry is not a coincidence or a metaphor. It is the cheapest way to get from one channel to many.
On this coast the branching runs the other way as well. These are tidal estuaries, and twice a day the water reverses. The channels are cut by flow in both directions, which keeps them open further inland than a river alone would manage.
The colour is sediment and vegetation. The pale blue-green is suspended material in suspension, densest where the channels meet the sea; the darker green between the channels is mangrove, which holds the sediment in place and is the reason the pattern is as sharp as it is.
From the ground none of this is visible. A person standing on one of those banks sees a river, a mud flat and a wall of trees. The shape only exists at an altitude from which no one lives.
