It refers to space during dam crestlevel; it is above maximum deposited beach face, storage bottom and normal water level as well as under maximum flood level.
某坝顶标高时，最高沉积滩面、库底、正常水位三者以上，最高洪水位以下的空间。
2
And just as each wave has a crest, it also has a trough. Sometimes your level of motivation will be like a rushing tsunami.
就像每个波浪有波峰，也有低谷，我们的干劲也是如此，会时高时低。
3
Revetments protect the space from dam crest to the line a certain distance, normally 2.5m, under the minimum water level of the dam upstream.