UCLA has a sandbox you can use to visualize different land elevations as well as how water interacts with lower lying regions. The best part is it’s also available to the public so if you’re near them try it out. See how large you can make your mountains!
This PlasticRoad concept is a modular design that has a longer lifespan than modern roads and can also drain water from the surface. The idea is that the roads can be fitted together like blocks, making it quick to repair and easier to build since instead of carefully assembling it on site you just remove the damaged site and lie down a new one. Some additional benefits are that new roads can be built swiftly and they are made from recycled components and can be recycled themselves.