The water that runs off the hillsides, meanwhile, also increases peak river flows, eroding the banks and raising the risk of landslides.
山坡无法蓄水，也增加了长江的最高水位，侵蚀堤岸，易引发决堤。
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Though the theory is still up for debate, experts think this colossal canyon was formed 17 million years ago, when the Colorado River carved through the gorge, eroding the rock.