Guardian: By the end of October, navigating the river Negro in the Amazon was quite risky. Hudson Andre, a boat driver, had to be double careful to avoid being stuck in one of the sand banks that could be seen everywhere. Seasonal rains fell a month later than usual, and the region went through the worst drought in the last century. The river Negro was 15m lower than it should be. “I had never seen it this low,” he says. Boats were unable to reach many riverside villages. Thousands of riverside communities…