Chongqing, Cairo plan to pursue joint UNSCO recognition

Baiheliang, or the White Crane Ridge, is a giant stone ridge located in the upper reaches of the Yangtze River (Fuling section). The ancient Chinese used stone-carved fish images as measuring tools and inscriptions as written records to monitor and document water levels. The site, used from 763 AD to 1963, is believed to be the world's most ancient hydrographic survey station.

The nilometer is an Egyptian invention designed to gauge the water levels of the Nile River. The Raoudha Nilometer in Cairo, constructed in 715 AD, stands as a prominent example of this technology.