A hydrological framework for persistent river pools

Abstract. Persistent surface water pools along non-perennial rivers represent an important water resource for plants, animals, and humans. While ecological studies of these features are not uncommon, these are rarely accompanied by a rigorous examination of the hydrological and hydrogeological characteristics that create or support the pools. Here we present an overarching framework for understanding the hydrology of persistent pools. We identified perched water, alluvial through flow and groundwater discharge as mechanisms that control the persistence of pools along river channels. Groundwater discharge is further categorized into that controlled by a geological contact or barrier (not previously described in the literature), and discharge controlled by topography. Emphasis is put on clearly defining through-flow pools and the different drivers of groundwater discharge, as this is lacking in the literature. A suite of diagnostic tools (including geological mapping, hydraulic data and hydrochemical surveys) is generally required to identify the mechanism(s) supporting persistent pools. Water fluxes to pools supported by through-flow alluvial and bedrock aquifers can vary seasonally and resolving these inputs is generally non-trivial. This framework allows the evaluation of the susceptibility of persistent pools along river channels to changes in climate or groundwater withdrawals. Finally, we present three case studies from the Hamersley Basin of north-western Australia to demonstrate how the available diagnostic tools can be applied within the proposed framework.