Some Challenges in the tropical rainforest is that Deforestation is common and its really bad because they're limiting the rainforest size just to build homes and towns. Basically, Just forgetting about the habitats and the animals and the other tribes.
Often, waterfalls form as streams flow from soft rock to hard rock. This happens both laterally (as a stream flows across the earth) and vertically (as the stream drops in a waterfall). In both cases, the soft rock erodes, leaving a hard ledge over which the stream falls