Evaluation of groundwater renewability in the Henan Plains, China

摘要

The sustainability of groundwater resources in the Henan Plains, located in the eastern portion of central China, has been threatened by both increasing industrial and agricultural pumping and periods of drought occurring since the 1990s. Therefore, there is an urgent need to improve water resources management in the Henan Plains. However, the recharge and annual renewal rate are very difficult to be calculated when based only on traditional hydrogeological methods because of inadequate hydrometeorologic data. In this study, tritium concentrations in groundwater and reconstructed ~3H concentration time series from 1953-2009 in precipitation were used to determine the annual groundwater renewal rate. The ~3H concentrations mostly ranged from 2.91 to 40.30 TU in the shallow groundwater with a mean ~3H concentration of 19.13 TU, which suggested that the shallow groundwater was recharged from modern precipitation after 1953 in the study area. Three exceptionally low 3H concentration(less than 1 TU) wells were sampled in Xinxiang, Puyang and Zhengyang which indicated that those wells contained deep old groundwater recharge before 1953 as a result of over-pumping. High renewal rates (more than 4%/a) of groundwater are located mainly in the recharge areas such as the Yellow River nearby and the pediments of Taihang Mountain, Songqi Mountain, Funiu Mountain, Dabie Mountain, where the groundwater extraction volume could be increased. Moderate renewal rates (2-4%/a) of groundwater are mainly in the runoff areas where the groundwater extraction volume can be kept at current levels. Low renewal rates (1-2%/a) of groundwater are located mainly in the discharge areas in the eastern regions of Nanle, Puyang, Shangqiu, Luyi where the groundwater extraction volume should be reduced. The lowest renewal rates of (less than 1%/a) groundwater are in Fanxian, Xinxiang, Yongcheng, Zhengyang and Xixian, where the groundwater extraction volume should be restricted.