Tutor: 0K, so what I'd like you to do now is to talk to your partner about your presentations on urban planning. You should have done most of the reading now, so I'd like you to share your ideas, and talk about the structure of your presentation and what you need to do next. Carla: 0K Rob. I'm glad we chose quite a specific topic-cities built next to the sea. It made it much easier to find relevant information. Rob: Yeah. And cities are growing so quickly-I mean, we know that more than half the world's population lives in cities now. Carla: Yeah, though that's all cities, not just ones on the coast. But most of the biggest cities are actually built by the sea. I'd not realised that before. Rob: Nor me. And what's more, a lot of them are built at places where rivers come out into the sea. But apparently this can be a problem. Rob: Well, as the city expands, agriculture and industry tend to spread further inland along the rivers, and so agriculture moves even further inland up the river. That's not necessarily a problem, except it means more and more pollutants are discharged into the rivers. Carla: So these are brought downstream to the cities? Rob: Right. Did you read that article about Miami, on the east coast of the USA? Carla: No. Rob: Well, apparently back in the 1950s they built channels to drain away the water in case of flooding. Carla: Sounds sensible. Rob: Yeah, they spent quite a lot of money on them. But what they didn't take into account was global warming. So they built the drainage channels too close to sea level, and now sea levels are rising, they're more or less useless. If there's a lot of rain, the water can't run away, there's nowhere for it to go. The whole design was faulty.