Whenever we see water it looks familiar. It doesn’t take very long to work out that we are looking at a river, lake or patch of sea. But this is quite impressive work by our brain, since we never see exactly the same thing twice. Every coastline, river, every pond even, is unique. Think of your two favourite stretches of water and I guarantee that they will appear quite different. Which is extraordinary when we think that the water itself is probably very similar.
Once we stop to ask why they appear different we are well on the way to realising that beauty is a good disguise. Pretty landscapes are nature’s way of tricking us into not spotting the clues, signs and patterns that lie in every scene. And when we know this trick we can beat it, we can look past it and find the clues.
The water may be the same compound but it is behaving differently and its relationship with land will be different in every place we travel to. Take the colour of water for example, every area of water will have its own colour. Most range between blue, green and grey. But there are surprises out there, like the salty Lake Hillier in Australia or Lake Setba in Senegal, that have both been colonised by an alga called dunaliella salina, turning these lakes bright pink.
At sea the colour of water has been used as a map for thousands of years and still is. Even in the age of GPS, it is much easier to pick your way through reefs in a small boat by using the colours you see than it is by staring at a screen. In fresh water scientists have developed a scale, called the Forel-Ule scale, to help decode the meaning of the colours we see. From the low nutrient waters that are indigo blue, to cola brown, which indicates very high concentrations of humic acids.
Some of the most interesting clues we will see will be found in patterns. Whenever a series of ripples of waves bump into something, they create a whole new set of patterns. We have all seen these patterns a thousand times, they are in every pond, lake, river and ocean we look at, but you have to know what to look for to make sense of them.
If ripples hit a stone in a pond, or great swell bumps into an island, the same patterns are formed. First the waves are reflected and these then bump into the incoming waves. This creates one unique pattern. Next the waves will bend and wrap around the island, because of a process called refraction, creating another pair of patterns on either side. Then there is an area of calm on the sheltered side of the island and finally there is my favourite pattern, where the the refracted waves meet each other once more on the far side and create a new cross-hatch pattern.
These patterns are very easy to spot once you know what to look for. And each time you see them you are tuning into the skill used by expert natural navigators, like the Pacific Islanders, who would sense these patterns in their outrigger canoes and use them to work out where invisible land was.
For more see the main page on the book How to Read Water