A study of the solute transport model for karst conduits based on CFP

To study the characteristics of solute transport for karst conduits, a coupling method of conduit flow process (CFP) and the modular three-dimentional transport model (MT3DMS) is proposed. For the purpose of probing into the impacts of hydrogeological parameter on solute transport for karst conduits, based on analysis of the fundamentals of CFP and MT3DMS, the authors established the concept model with one sink hole and four conduits. The results of the coupling model show that the CFP model permits the exchange of groundwater between matrix and pipe, and the tailing feature of the breakthrough curve for karst conduits is well depicted. With the decreasing effect from porosity and the increasing effect from pipe diameter and the increasing pipe conductance and hydraulic gradient, the curve peak became larger, and the time to reach the peak becomes quicker and the symmetry of the curve is more apparent. Thus, the coupling model of CFP and MT3DMS can depict the characteristics of solute transport for karst conduits, but cannot simulate the multi-peak curve. How to generalize the physical characteristics of karst conduits is a way to resolve the multi-peak issues.