Chinese idiom · 成语
江河日下
Meaning
Rivers flow downward daily; steady decline.
Character by character
Origin and story
literaryWater flowing downward provides the image behind this expression for continuing decline. A related passage in Su Zhe's Luan Cheng Ying Zhao Ji (栾城应诏集) compares the unchecked course of human tendencies to great rivers rushing downhill day and night. This is an earlier parallel image, not secure proof that Su Zhe coined the exact four-character idiom.
The exact wording appears in later works, including Zhang Xuecheng's Wen Shi Tong Yi (文史通义), where it describes deterioration that a capable person may struggle to reverse. In ordinary modern usage, a business, an institution, or a state of affairs can be 江河日下. The image concerns downward movement, not a literal daily fall in a river's water level.
Sources and further reading
In everyday life
这家店不再重视服务，生意也就江河日下了。
Once this shop stopped taking service seriously, its business went steadily downhill.
Negative: indicates a continuing decline rather than a single temporary setback.