Darcy's Law Expressed by Chemical Index

The Darcy's formula expressed by chemical indexes (ion activity a and saturation index β) is derived with the aid of the kinetics of multi-mineral dissolution. The implication of the formula and the relationship between the formula and the original Darcy's law expressed by hydraulic index (hydraulic gradient, Ⅰ) are discussed here. An analytic expression is established in this paper for the determination of the residence time of groundwater by chemical indexes, whose equivalence to isotopic age is studied. The formulas are derived from the calculation of permeability coefficient (K), conductivity coefficient (T) and actual velocity of groundwater (U). Finally, this paper introduces hydrogeological chemical kinetics constant (k_j) and its determination method, differential and integral equations for chemical kinetics of groundwater in three-dimensional space.