Where can I take the one day tourist bus from Xian to Hukou

Well, there is direct bus running at 08:00 from Xian Chengdong Bus Station to Hukou Waterfalls. It arrives at Hukou at 13:30 and costs about CNY120, but it doesn't go back the same day. It runs back at 08:00 the next morning. If you want to go back in the same day, the only way for you is to take bus from Hukou to Yichuan first and then transfer to another one to Xian. The last one departs at 17:30 from Yichuan. It arrives in XIan at 22:30. In this way, you may be very tired.