Tracing sources of recharge to groundwater in the Northern Henan plain using environmental isotopes

This paper demonstrates that isotope methods can provide independent insight into the recharge mechanisms and estimate relative contributions from multiple sources. Isotopic data from groundwater throughout the Northern Henan Plain were used together with classical hydrogeological information to study the sources of recharge, to locate recharge area and to understand recharge mechanism. The tracer data indicated that major sources of water to the plain included recharge from local precipitation in the piedmont and seepage or irrigation from the Yellow River along the north bank of the river. Significant evaporation occurred prior to recharge. The mean width of the seepage zone from the Yellow River is about 10 km. More than 60% recharge for groundwater is from the Yellow River within this seepage zone. Tritium distribution mainly depth dependent suggested the active groundwater recharge zone has a thickness of about 150 m in study area. These waters were younger than 50 years and therefore were renewable.