Variation in groundwater resources carrying capacity in Beijing between 2001 and 2015

Owing to the over-extraction of groundwater resources in Beijing over the past 40 years, Beijing has faced an increasingly sharp decline in groundwater level and storage. Few studies have been reported the variation of groundwater resources carrying capacity in Beijing. In this paper, groundwater resources carrying capacity was defined and assessed based on the available groundwater quantity and water use efficiency. Our results indicated that the water supply from groundwater in Beijing was higher than that from surface water. The agricultural water use efficiency and industrial water use efficiency increased from 2001 to 2015, except other industries water use efficiency decreased slightly from 2014 to 2015. The comprehensive water efficiency increased from 97 ¥·m^-3 to 620 ¥·m^-3 between 2001 and 2016. Our results also showed that the actual GDP supported by the groundwater resources increased from 2 636 million Yuan to 11 469 million Yuan and then decreased to 11 284 million Yuan. Before 2010, groundwater resources in Beijing were overloaded, but this alleviated after 2010. Although the actual GDP supported by groundwater resources was lower than theoretical GDP, groundwater resources had faced a serious situation; therefore, increase in the surface water supply and improvement of the comprehensive water efficiency would be two effective ways to improve groundwater resources management in Beijing.