private void calculateDownslopes() {
        for (Corner c : corners) {
            Corner down = c;
            //System.out.println("ME: " + c.elevation);
            for (Corner a : c.adjacent) {
                //System.out.println(a.elevation);
                if (a.elevation <= down.elevation) {
                    down = a;
                }
            }
            c.downslope = down;
        }
    }