The water of a river in Tianba Village has bisected into different colors as a result of flooding. The emerald clear water on one side, while the yellow and muddy on the other side. 

It's not magic of nature or artificial scenery, but a demonstration of deforestation and why forests matter to us.

Before figuring out the mystery, we must to understand the geographical location of the river. Tianba is a small village in south China's Hunan Province, and its river has two main branches. One tributary coming from a township called Wudaoshui, the other one flowing through the forests of Badagong Mountain National Nature Reserve.

Forests can soak up excess rainwater like a sponge, meanwhile protect the soil from washing away by catastrophic floods. Established in 1986, Badagong Mountain National Nature Reserve is the first national nature reserve in Hunan Province. As its ancient and unspoiled forest ecosystem is well protected, the impacts on river and water preserve are obvious.

The forest has multiple layers, including the forest floor, herbs, shrubs, understory, canopy, and emergent. The dense branches and leaves on the higher layers can intercept rainfall, which reduces the force of rain on the earth. The loosen litters and humus of the forest floor act like a sponge, which can storage a great amount of rainwater, therefore minimizing the effects of floods and landslides.

The abnormal view in the video is caused by deforestation along a branch of the river in the Wudaoshui township that lost 60 percent of its forest in 1958. Despite conservation programs have been carried out for years, the forest recovery needs time. Thus the river flowing through the area is still muddy; while the forests in Badagong Mountain National Nature Reserve have been preserved until today, and the water from the region is clean and clear. 

(Video and image provided by Gu Zhirong)

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