Graffiti that hasn't been approved should be illegal. It cost money to get the graffiti covered or removed. It is considered vandalism anyway when someone pains or draws on someone else property without their approval. So, yes, graffiti should be illegal IF it hasn't been approved by the county or the owners or county area etc.
The official definition of graffiti is, "writing or drawings scribbled, scratched, or sprayed illicitly on a wall or other surface in a public place". Meaning that graffiti is a form of vandalism. And because vandalism is illegal, I don't think any other forms of it should be considered 'ok'. That is my opinion on the subject. Note my 'opinion'.
Although you might not want to speak publicly about your project, if you do good enough you'll be rewarded! We aren't rewarded when actually speaking with people, but its good to know you did well because that'll make you more confident to talk to others just the same way.
What would best show the locations of your area's natural resources, such as rivers and forests is a map, since a map is a diagrammatic representation of an area of land or sea showing its physical features, like cities, roads, rivers, etc.
