I wish I could remember the details, but I saw a documentary a few years back about an area of the African plains where the animals would come to enjoy the waters of the annual flood of this certain river. But of course there aren't any heavy rains and no mountains, so where does the water come from? Well, traveling up the river they show that it originates in a forest. Recently the river has become smaller and smaller, drying up in some places. It's pretty clear that the reason is that development in and around the forest is of course shrinking the forest itself, thus less area to collect and retain water, thus drying up the river, thus thinning the plains animal population through drought.