但亚洲地区的蓄水层 — — 其中许多蓄水层的形成还要追溯到几千年之前，当时中国北部地区的气候比现在更加潮湿 — — 已经无法再通过降雨得到定期补充。
But Asia’s aquifers – many of which were formed millennia ago, when areas like northern China had a more humid climate – are no longer being replenished regularly by rainfall.