Application of chloride profile and water balance methods in estimating groundwater recharge in Luanjing Irrigation Area, Inner Mongolia

A Study was carried Out to investigate the use of the chloride profile method in conjunction with the water balance method to estimate the annual groundwater recharge in both natural and irrigation sites ill Luanjing Irrigation Area, Inner Mongolia. Groundwater recharge from precipitation, estimated by the chloride profile method, is less than 0.1 mm year(-1) which accounts for just 0.06% of the long-term average annual rainfall, indicating that rainfall presently plays a minor role in the groundwater recharge. It appears that recharge events only occurred after heavy rain or sustained rainfall events. In the cropped area, the chloride profile method indicated that the average annual recharge is 268 nun year(-1) with all infiltration rate of 32.5%, which is reasonably consistent with the 33.1% obtained by the water balance method in 2007. The Study shows that about one third of that water is discharged back to the groundwater.