Estimating the costs of managed aquifer recharge under uncertainty with examples for town water supply in regional Australia

Abstract

Drought risks exacerbated by climate change exposes water scarcity issues particularly in arid to dry subtropical areas globally. Recurring droughts have highlighted town water security deficiencies in regional Australia. Managed aquifer recharge (MAR) is proven internationally as an effective tool for increasing drought resilience and sustainability of water resources. Uncertainty concerning costs of MAR schemes has been a barrier to wider implementation. This study presents a framework for assessing costs of MAR for well injection and infiltration basin systems across a range of conditions and scales relevant to town water supply. Novel methods were developed to account for uncertainty, capture time-varying volume dependent operating costs, and examine disaggregated capital and operating expenses through global sensitivity analysis. Levelised costs were inversely proportional to scheme scale although diminishing rates of return were shown for larger capacity systems driven by increased volume-dependent operational costs. When accounting for aquifer storage losses, levelised costs of recovered water were up to double the costs of recharge. Global sensitivity analyses revealed input variables that determined the dominant disaggregated costs were also the most sensitive and that these changed in relation to scheme scales and operating conditions. The methods allowed estimated costs and sensitivities for conceptualised MAR schemes for six towns in Australia’s Murray-Darling Basin to be oriented within the envelope of results. This demonstrated the transferability and applicability of results for providing indicative costs and informing specific investigations to reduce uncertainty in viability assessments of MAR over a range of scales and conditions. Graphical Abstract: (Figure presented.)