The country gate slopes up and down to the yard. Is there anything special?

The gate is a courtyard with an up and down slope. What's the point? Last time I entered the gate, the slope up and down may have been solved. Then when I went up and down, Mr. Du didn't want to be washed away by the water. If you enter the yard, is it snowing downhill? If it is a slope, he calls it a water inlet. If it is uphill, it is not water, and it will not be bad inside.