The researchers pointed out that low-frequency processes, such as fluctuations in stream flow and groundwaterlevels, would not usually be apparent to human populations.
研究人员指出，低频过程诸如河流流量和地下水水位的波动，通常不会对人类产生明显影响。
2
The problems associated with rising groundwaterlevels are not restricted to developed countries.
地下水位持续上升问题已成为当前一个国际性问题。
3
Fast decline in groundwaterlevels will lead to changes in geological formation, and may even trigger earthquakes.