As you really didn't specify where you want it to walk, I needed to get creative, there might be a better way to do this, but it should work.
if(myPlayer().getPosition().getY() > 3678){
ArrayList<Position> closestTile = new ArrayList<Position>();
if(closestTile.size() <= 383){
for(int i = 0; i <= 383; i++){
closestTile.add(new Position(3678, 2946 + i, 0));
}
}else{
closestTile.sort(new Comparator<Position>() {
public int compare(Position entry1, Position entry2) {
return entry1.distance(myPlayer()) - entry2.distance(myPlayer());
}
});
getWalking().webWalk(closestTile.get(0));
}
}else{
//do tele
}