Why is a topographical map important?

The next part of creating your planet for your fictional story will be creating a topographical map of your planet. This may sound easy, you think to just draw a map with a few squiggly lines then decide which gaps are land and which are water but I’m talking about a little more thought than that. First of all, remember the surface of a planet is always changing due to plate tectonics or the heat inside the planet moving to the exterior of the planet, expanding one ridge while pushing another area under the crust of the planet somewhere else. Knowing where those boundaries are can show where mountain ranges should be, where large canyons should be, where volcanoes are common, show things like probable locations for earthquakes, and where tidal waves are likely to go often.
Now that you know where your plates are, it should be easier to decide where your continents will be. Something to keep in mind is that on Earth science says that the continents were once one big continent. For that reason similar soils are found near coastal areas of different continents as are similar fossils. Another thing to consider is that humans only use about .08 percent of all water on the Earth and none of that is from the oceans as they are salt water. If you want to make fewer oceans, you may result in less rain so more deserts on your planet but you would have more landmass for your species to adapt to. It could also mean less marine life so there would be fewer fishermen and buying any kind of marine animal would be expensive. You could also think about making more usable water on your planet which could lead to faster technological evolution if water isn’t a problem. Imagine how much easier life would have been for the ancients if the ocean was fresh water. Then again, if they had plenty of fresh water on the coasts, would they have ventured inwards looking for a different life?
Once all these things are decided, you only have a few more steps before working on your species. The next step will be looking at where your climates are and what you need to decide about those.