Response of phreatophytes to short‐term groundwater pumping in a semiarid region: Field experiments and numerical simulations

AbstractBalancing the water demand between human usage and ecosystems remains a challenge in water‐limited regions where one of the main groundwater uses is short‐term pumping. A 23‐day pumping test was performed in a semiarid site of north‐west China to test the hypothesis that native phreatophytes can tolerate short‐term pumping. The monitoring indicated that sap flow velocity of groundwater‐dependent willow trees began to decrease on Day 4 after pumping and almost fully recovered on Day 9 after the cessation of pumping. Numerical simulations using HYDRUS‐1D were conducted for the period of 1954–2013 to assess the response of phreatophytes to groundwater withdrawal under various climatic conditions. The modelling results reveal that phreatophytes can recover from the stress induced by groundwater pumping because they can adapt to short periods of water stress using physiological and morphological traits and the degree of water stress depends on the amount and/or frequency of rainfall during and after pumping. Therefore, pulsed pumping, under particular climatic conditions, could be used to reduce negative impacts of groundwater extraction on phreatophytes, while still providing groundwater for socio‐economic activities in semiarid zones.