据新华社消息，阿塞拜疆国家水文委员会的科学家证实，去年里海水位平均下降了20cm．据哈萨克斯坦日前出版的半月刊《生态信使报》报道，阿塞拜疆地理学教授韦利耶夫根据最近里海水位有所下降这一现象提出了里海水位升降具有周期性的假说．他认为，从现在开始至下个世纪中叶， According to Xinhua News Agency, scientists from the Azerbaijani National Hydrological Commission confirmed that the water level in the Caspian Sea dropped by an average of 20 cm last year. According to a semi-monthly issue published by the newspaper Ecometrics in Kazakhstan recently, Azeri professor of geography Velieuf proposed the hypothesis of periodicity in the rise and fall of the Caspian Sea, based on the recent decline of the sea level in the Caspian Sea. He believes that from now until the middle of the next century,