Sensitivity of recharge estimation to the pore connectivity parameter of vadose zone rocks

Abstract

Information on recharge value is necessary for solving different classes of hydrogeological problems. One of the methods of recharge estimation is simulation of flow in vadose zone. Soil hydraulic parameters are used to estimate recharge by flow in vadose zone. One of the hydraulic parameters is the pore connectivity parameter l. The sensitivity of estimated recharge to the value of pore connectivity parameter, especially under humid climate conditions, is studied insufficiently. In present study, the experimental values of soil hydraulic parameters of samples from two different sites with various landscape conditions and vadose zone structure (forest landscape on sand and field landscape on loam) were used to estimate recharge.Recharge estimation was also carried for the value of l=0,5 and for reported values of l parameter for certain type of sediment. Analysis of calculation results demonstrated that using fixed value of l=0,5 leads to significant overestimation of calculated recharge both for forest and filed landscapes, which emphasizes the importance of experimental definitions of soil hydraulic parameters for recharge estimation. The analysis of the water balance components showed that the increase of estimated recharge with enhancement of l value is mainly associatedwith the decrease of evaporation from the upper soil layer.