Predicting the impact of heavy groundwater pumping on groundwater and ecological environment in the Subei Lake basin, Ordos energy base, Northwestern China

Groundwater is increasingly exploited for energy production in arid areas globally, which will inevitably disrupt the natural equilibrium of groundwater and the ecological environment. A groundwater flow model for Subei Lake basin, Ordos energy base, was developed and calibrated to predict groundwater levels' variation and the impact of heavy groundwater pumping on the ecological environment for the period 2010–2039 under two different pumping scenarios. Results showed that rainfall infiltration and groundwater evapotranspiration were the major source/sink terms for the groundwater system. The obvious groundwater depression cone will be formed in the production field at the end of 30 years and the maximum drawdown will be 11.70 m if the waterworks maintains the present situation. However, recovery of groundwater level will be obvious and the groundwater depression cone will disappear as a result of the implementation of the water diversion project. The increased volume of groundwater pumping between the two scenarios was derived from storage depletion, the activated lateral inflow, the captured groundwater evapotranspiration, lateral outflow and discharge into Subei Lake. Groundwater pumping from Haolebaoji waterworks has caused the decline of the Subei Lake and the noticeable degradation of phreatophyte.

Identifying the impact of Energy Base Water Project on groundwater using high-frequency monitoring data in the Subei Lake basin, Ordos, Northwestern China

Groundwater is increasingly exploited for energy production in arid regions, which necessitates a deeper insight into the impact of the enhanced human pressure on the groundwater. This study applied an integrated method (statistical analysis, water table fluctuation method, hydrograph analysis and remote sensing) to identify the impact of Energy Base Water Project on the groundwater in the Subei Lake basin. Groundwater levels in eight observation wells at 30 min intervals during the 2013–2014 period were monitored using automatic groundwater monitoring data loggers. Results showed that precipitation infiltration, irrigation return flow, groundwater pumping and evapotranspiration controlled the hydrodynamics of unconfined groundwater. The average evapotranspiration rates in the Quaternary phreatic aquifer and the Cretaceous phreatic aquifer were 6.15 and 12.48 mm/d. The unusual hourly hydrographs fall into three patterns (mutational, irregular and gradual hydrographs). Different recovery times after being influenced by pumping may be related to the presence of the mudstone lenses. The extent of the groundwater depression cone was qualitatively identified by gradual hydrographs, which may spread from the center area to the western boundary. Only some individual wells from Haolebaoji waterworks had conducted the intermittent pumping activities at random times and caused the decline of the lakes.