For the record, and from my limited readings, I don't think it's a problem that can be "solved," at least not in the way that most people think of problems being solved. It's one of those complex problems that has to be "managed." Right now it appears that it's being managed poorly. The trick is to manage it better.
Manage it? Throw their butts out and build an impregnable fence. Back up that fence with cameras, sensors, Border Patrols or soldiers. That's how I'd manage it. The cost be damned. We're going broke now.