水灾发生的影响英文表达可以是"flooding impacts"或"the effects of a flood"。

水灾是由于某些原因导致的洪水，可能是由于降雨过多，河流溢水，海啸或洪水等。水灾会对人类的生命和财产造成严重的损害。

一些英文例句及其中文翻译如下：

The flooding caused by the heavy rains has had a significant impact on the local community. (由于大雨造成的洪水对当地社区产生了重大影响。)

The effects of the flood were devastating, with hundreds of homes and businesses being destroyed. (洪水的影响是毁灭性的，数百座房屋和商业场所被摧毁。)

The flood has disrupted transportation and left many people stranded. (洪水中断了交通，使许多人被困。)

The floodwaters have contaminated the water supply, making it unsafe to drink. (洪水污染了供水，不安全饮用。)