Hysteresis Observed In SC vs. Q Relationships and Its Implications On Flowpath Identification

The hysteresis shown in specific conductivity (SC)-discharge (Q) relationships during rain events has been previously utilized to verify the presence of preferential flows of new water. This series of observations were made in a catchment where isotopic data have shown that stored water is the predominant outflow during rainfall events. The SC response during rain events and a laboratory column test complemented the conclusion of isotopic study, viz. the runoff mechanism is discharge of stored (non-event) water. It is shown that any runoff mechanism giving a higher SC in the falling limb of hydrograph (for the same Q value) will generate an and clockwise hysteresis in the SC-Q relation, even in the absence of a preferential flow of new water.