Heavy rain can quickly wash away the rich top soil on flat, open land.

飘泼大雨能很快地冲走那里的平坦开阔的表层土壤。

youdao

At the very top the flat, a door was open and Shazzia welcomed me with a smile.

BBC: Afghanistan: Through veiled eyes

Near the top, a path broke off and led to a flat open plot, where the castle should have been, but, save for an old stone wall, there were no ruins to be seen.

NEWYORKER: Master of Play