moat around a city

strokes 14
strokes after radical 11
吃一堑,长一智 吃一塹,長一智 chi1 yi1 qian4 - zhang3 yi1 zhi4
Fall into the moat and you'll be wiser next time (idiom); One only learns from one's mistakes.

地堑 地塹 di4 qian4
trench, rift valley

东非大地堑 東非大地塹 dong1 fei1 da4 di4 qian4
Great East African rift valley