Laoniuwan has two main parking lots: Chengwan and Niuzhuanqiankun, about a dozen kilometers apart.
Most drivers park at Chengwan, then take a boat to Tieniu Square (the scenic area directly adjacent to Niuzhuanqiankun). From Tieniu Square, you can see the first bend of the Yellow River, then take a bus back to Chengwan to pick up your car.
However, every year in mid-to-late August, flood discharges cause the Yellow River water level at Laoniuwan to be very low, even drying up in some sections. Boat service is suspended, forcing you to go to Niuzhuanqiankun. From there, take a shuttle bus to the terminal, then walk 1.1 kilometers to Tieniu Square. This walk is lined with farmhouses and B&Bs, making it convenient for dining.
During flood discharges, the water level is low and yellow, severely impacting the landscape. I personally think the scenic area should offer discounted admission during this period.