Schematic representation of chloride concentration changes following land-use change. a Before and b after land-use change.

Postdoctor HUANG Tianming and professor PANG Zhonghe have published a paper onestimating groundwater recharge following land-use change using chloride mass balance of soil profiles.

They research on the groundwater recharge at Guyuan and Xifeng in the Loess Plateau of China. Results from the Guyuan terrace region show that groundwater recharge beneath natural sparse smallgrass was 100 mm/year, but the conversion to winter wheat about 100 years ago has reduced groundwater recharge to 55 mm/year. At the Xifeng Loess Plain the conversion from winter wheat, with groundwater recharge at 33 mm/year, to apple orchard 7 years ago has led to chloride accumulation to 5 m below land surface, suggesting the recharge rate has been reduced.

This is in agreement with previous studies in these areas which have shown that the regional afforestation and other land-use conversions have resulted in deep soil desiccation and have caused an upper boundary to form with low matrix potential, thus preventing the soil moisture from actually recharging the aquifer.

Huang et al. Estimating groundwater recharge following land-use change using chloride mass balance of soil profiles: A case study at Guyuan and Xifeng in the Loess Plateau of China. Hydrogeology Journal，2011，19：177-186（Download Here）