Definitions Riverbed Conductance = (Kv/m) wL Leakance = Kv/m Resistance = m/Kv Kv = vertical hydraulic conductivity of riverbed sediments m = thickness of riverbed sediments w = width of the river L = length of the river within the cell

GHB L Q = C (hB - h) C = Conductance = K A/L K is the hydraulic conductivity of the aquifer between the model and the lake; A is the area of the boundary cell, perpendicular to flow. hB

• Streamflow Package (Prudic 1989)- see p. 127 A&W Allows for dynamic interchange of groundwater and streamflow; solves for stream stage. Manning’s Equation: d = (Q n / C w S1/2)3/5 n is Manning’s Roughness coefficient New MODFLOW Package available in MODFLOW2000. • Streamflow Routing Package (Prudic 2004) Q

• Lake Package – Available in MODFLOW2000 (Cheng and Anderson, GW,1993) (Council, 1998) (Merritt and Konikow, 2000) Solves for lake levels Other packages: • Wetland Module (Restrepo et al., GW,1998) • MODBRANCH (Swain, 1993)

Head Dependent Boundaries in original MODFLOW88/96 Q = C h • River Package • Drain Package • General Head Boundary (GHB) Package • ET Package Prudic’s 1989 Streamflow Package and a few other packages have since been added to MODFLOW88/96 and are available when running MODFLOW88/96 in Groundwater Vistas.