1.Here there is a gradual descent to the sea.
这里有个通向海的缓坡
2.This gradual descent continued through 2008, the last year for which data are available.
这一逐渐下降趋势持续至2008年底,即可获数据最新年份。
3.a gradual descent from land to sea
由陆地逐渐倾斜至海