This image depicts a preliminary model of the accumulation of water flowing across the landscape during a rainfall event. Rain is assumed to be uniform across the area, and infiltration is ignored (this is a good assumption for intense, thunderstorm-driven flow events). Dark areas in the image shed water more effectively; light areas in the image are places where water flows in from adjacent hill slopes or upstream channels. The model is being improved to deal with flat sections of channel, where flow stalls in the current model.