http://www.geosociety.org/gsatoday/archive/17/10/pdf/i1052-5173-17-10-4.pdfsoil erosion is a very important topic, read this!
Also, think about the state of Louisiana. It's pretty much created COMPLETELY by the Mississippi River delta as it has spread out through history. The channels used to be able to snake and spread out the sediment evenly, but the river channel has since been contained. Why? It would be economically inefficient - New Orleans is a HUGE port, and the USA would be hurt economically if the channel was to just suddenly shift to the west or east over a few years. But think about how that affects the state. There's no new sediment! Which means Artificial levees = deeper (water erodes down instead of out) river channels + no flooding + no meandering = no soil
This is also related to New Orleans sinking and being prone to natural disasters like hurricanes. The city is literally below sea level. Why? No new sediment! The sediment that was deposited there contains a lot of ground water, obviously. New Orleans needs that water, so the city draws it up, leaving a ton of 'open space' below the city. The city also forms new buildings, grows in population, etc, and becomes HEAVIER. These two factors cause it to sink...
From a geology perspective, "Humans as Geomorphic Agents" would be a good topic if you like to talk about rivers.
Another thing could be to talk about the production of corn and beef and how toxic it is to our environment and our bodies. Corn fed cows = unhealthier beef = unhealthier people. Corn fucking sucks, takes up shit tons of water and soil and space... pesticides = no bees = global epidemic! and SOIL EROSION! Also, humans started eating meat essentially because we needed the calories, which we obviously most definitely do not need anymore, so maybe you could talk about how we need to focus far more on nutrition! If you have netflix, there are a few documentaries about healthy food. I remember one being called "Food Matters", where they essentially talk about what's fucked up with the usa's food style.
Groundwater is also a very, very important issue, and will very likely be a hot topic for the coming generations. Try checking out a copy of "Unquenchable" from the library. It covers many topics about what's wrong with water supplies in the usa.
I've also heard about insects being a fantastic source of protein/calories and easy enough to harvest, and that they might actually be a final way to feed an overpopulated planet.
This post was edited by JadeBlade23 on Jun 7 2013 05:25pm