An approach to the relationship between recharge, runoff and drainage of groundwater in the typical red beds: An example from Rongchang in Chongqing

Particular attentation has been drawn in recent years to the relationship between recharge, runoff and drainage of groundwater in the water research on the red beds. Examplified by Rongchang in Chongqing, the relationship between recharge, runoff and drainage of groundwater is explored, in detail, on the basis of hydrogen and oxygen isotopic dating in integration of the 1:50 000 hydrogeological survey. It is concluded that the shallow groundwater in the red beds is derived dominantly from meteoric water, and subordinately from surface water. The groundwater in the study area has the features of recharge in situ and discharge nearby, and exhibits a trend of the depletion in mountains, ridges and hills and enrichment in gullies, valleys and swales. The geomorphological features are believed to be the main controlling factors for the enrichment of groundwater.