Flooding is a major problem worldwide, especially in poorer countries. Scientists are studying how well a 1-D computer model can predict floods in different rivers. They compared the model's predictions to a more complex 2-D model. The results showed that the 1-D model worked better for some rivers than others. In rivers with wide flood plains and varied terrain, the 1-D model's predictions were less accurate. The model was also sensitive to the size of the flood.