资源环境科技发展态势分析平台

The water table fluctuation method of estimating recharge is widely used because it is conceptually simple and easy to implement. The major source of uncertainty in the recharge estimates come from the specific yield. The apparent specific yield has a dependence on the depth to water table that makes its measurement difficult (if not impossible) for appropriate use in the water table fluctuation method. This study has treated the specific yield as a conceptual parameter that cannot be measured and has constrained it using a rejection sampling approach using probabilistic estimates of net recharge from the chloride mass balance method and excess water derived from the difference between precipitation and remotely sensed actual evapotranspiration. The method developed here provided probabilistic estimates of the ultimate specific yield and a probabilistic time series of gross recharge, both important in shallow water table environments. An additional benefit of the method is that by jointly constraining the three different recharge types (i.e., excess water, gross, and net recharge) they are assured of being internally consistent. The method was implemented for 58 bores across four catchments in Northern Australia that may see increased development in coming years.