A NEW CHLORIDE LEACHING APPROACH TO THE ESTIMATION OF DIFFUSE RECHARGE FOLLOWING A CHANGE IN LAND-USE

A new approach has been developed to estimate the increase in groundwater recharge following land-use modification. The approach uses the degree of leaching of chloride to quantify soilwater drainage below the root zone which ultimately leads to groundwater recharge. It is more general than similar previously reported techniques for analysing transient chloride profiles to infer recharge rates, and hence has wider application. We have applied the technique to a field situation in southern Australia where clearing of native vegetation for agricultural production leads to large increases in groundwater recharge. The examples serve to demonstrate the technique and some of the practical difficulties in the application of solutes techniques to recharge estimation.