Need to think of an environmental engineering solution for a country's problem(problem in a specific country)?

i have to pick a country, a problem in that country, and think of an environmentally conscious engineering solution for it. can be any country and can be any kind of problem. so for example if i did a 3rd world country i would probably pick something like water contamination but if i picked the U.S. i might do something related to transportation or cutting down on paper used by text books. also its best if i pick something i can make a small model of or some kind of visual representation because you get more points for that. there are so many countries and problems out there its kind of hard to choose one. any suggestions would be great. Thanks :)Need to think of an environmental engineering solution for a country's problem(problem in a specific country)?Currently I am writing a term paper on green roofs (living roofs). It's literally a roof garden. Helps reduce pollution and cut energy usage. Perfect for U.S.