Laserfiche WebLink
Saturated Zone Model <br /> Dx -cxeV, Dy =aeV , Dz = a8V (B-3) <br /> where <br /> t , oy a-. = dispersivity in x,y, and z directions [ml (longitudinal, <br /> transverse and vertical dispersivities) <br /> V = Darcy velocity [m/d] <br /> The Darcy velocity is defined as follows <br /> V=K i (B-4) <br /> where <br /> K = saturated zone conductivity [m/d] <br /> i = hydraulic gradient [m/m] <br /> The seepage groundwater flow velocity, V, is calculated from the Darcy velocity <br /> V 9 (B-S) <br /> where the variables are as defined previously <br /> The dispersivities can be calculated by the model or the user may enter values If the <br /> code calculates the dispersivities, the longitudinal dispersivity(a,,) is calculated from <br /> In % = -3 795 + 1774 In x- 0 093 (in X/ (B-6) <br /> where x is the distance downgradient (m) from the source to the receptor well (Gelhar <br /> et al , 1985) Equation B-6 is different from the equation used to calculate dispersivity <br /> in the Vadose Zone model (equation A-32) where the dispersivity in the vertical <br /> direction(the direction of groundwater flow) is being calculated In equation B-5, the <br /> dispersivity is calculated in the horizontal direction Both these equations are based <br /> on empirical data and not derived from mathematical "first principles" <br /> From an American Petroleum Institute's report (1987), the transverse and vertical <br /> dispersivities are assumed to be related to the longitudinal dispersivity as follows <br /> • <br /> B-5 <br />