衰退过程 meaning in English

degenerative process
deteriorative process

Numerical analysis for the decline of subsurface flow
地下水流衰退过程的数值解析
The development and decline of subsurface flow in soil changing slope due to rainfall infiltration were studied with numerical analysis
摘要用数值解析研讨了降雨渗透变化坡面的地下水流的进展和衰退过程。
In numerical calculations , the effects of rainfall pattern , shape of slope layer and changing slope to the development and decline of subsurface flow were examined
数值计算验算了降雨的方式，斜坡地层的形状以及坡度的变化对地下水位进展和衰退过程的影响。