National Geographic: This story is part of a special series that explores the global water crisis. For more, visit National Geographic’s Freshwater website. Memories of floodwaters in New Orleans’ Lower Ninth Ward are still fresh in the minds of those displaced by up to 20 feet of Hurricane Katrina storm surge as it poured through a levee break there five years ago. It is not surprising that people in this lower-income neighborhood on the banks of the Industrial Canal have a tenuous relationship …