Water is colorless, odorless, and tasteless – we all know this from experience, and many of us have learned it as a strict definition back in school.
But have you ever watched a kid drawing water? Which crayon or pencil did they choose? Blue, right? We learn as we grow up that, on white paper, it’s the “right” color to use, and we also hear expressions like blue ocean strategy, the Blue Danube Waltz, or the Blue Lagoon, so that’s precisely how waters quite often appear in our mind.
Why blue? It’s all about physics or, to be more precise: optics. First of all, it’s important to note that one of the most common answers is true: what adds to the coloring of large bodies of water, such as rivers, seas, and oceans, is the reflection of the sky above, indeed. However, there is a more important reason: water absorbs the red spectrum of light, and the blue part of the spectrum is left behind to be reflected back as we watch it.
How about Tisza? Why is it called ‘blond’?
Indeed, Tisza was once known as ‘blond’ because the sand it picked up colored the water a beige. The silt came from the northern mountains and was whirling down to the southernmost part of the river.
Nowadays, Tisza has become much clearer, and it worries experts. Why is it hard to restore Tisza’s blondeness? The reason is that the lack of rainfalls reduces water levels until groundwater becomes the source of the river and its tributaries. When the groundwater reserves are depleted, the water yield of Tisza is diminished, while the increasingly extreme weather doesn’t allow groundwater to replenish as it used to.
Why is it hard to restore Tisza’s blondeness?
It’s known that more water can infiltrate into the soil in a calm rain than in a pouring one, especially if that soil is dry already, and flora can also slow down and store rainwater. Therefore, keeping and restoring the quantity and quality of vegetation in Tisza’s catchment area is essential.