Overestimated groundwater 14C ages triggered an inexpediency of water policy in China

Abstract

Northern China has been facing a serious problem of groundwater scarcity. The government developed restrictive policies on groundwater extraction, and designed the South-North Water Transfer Project (SNWTP) to transfer water from the Yangtze River in southern China to the arid region in the north. However, contrary to expectation, groundwater levels in northern China have been rising significantly before completion of the project. Due to misapplication of the 14C dating method, the age of deep confined groundwater in arid northern China has been overestimated. This classifies the groundwater as palaeo-groundwater with little recharge, which results in the prohibition of groundwater extraction and SNWTP. Significant tritium concentrations recently reported in the so-called palaeo-groundwater, along with rising groundwater levels, imply recent groundwater recharge in arid northern China.