Representation of hysteresis property of recharge to phreatic surface in numerical models

For the hysteresis property of infiltration from water sources,the weight coefficient method of hysteresis recharge in groundwater models is introduced,in which only a coefficient remains to be specified.An ideal one-dimensional numerical model with homogeneous media and constant head at the bottom boundary is employed to unveil the change in the unknown coefficient.By comparison of the seepage at the bottom boundary from saturated groundwater model with different hysteresis recharge weight coefficient and a saturated-unsaturated groundwater model,it is concluded that the hysteresis recharge coefficient decreases with the depth to groundwater level,and increases with hydraulic conductivity of the media.The relationship among the hysteresis recharge coefficient,groundwater depth and hydraulic conductivity is obtained from 40 model tests.The results provide reference for the description of hysteresis problems in the saturated groundwater flow model and improve the accuracy of groundwater flow modelling.