Hydrological complexity and climate implications in Australia’s arid zone: A decade of high-resolution rainfall observations

• Published in: Journal of hydrology. Regional studies Vol. 51; p. 101643
• Main Authors: Acworth, Ian, Bernardi, Tony, Andersen, Martin S., Rau, Gabriel C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2024; Elsevier
• Subjects: Arid–arid zone hydrology; Australia; Ephemeral runoff; Rainfall; Arid–arid zone hydrology; Rainfall; Ephemeral runoff; Australia
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2023.101643

Study region: The study was carried out in Fowlers Gap (New South Wales, Australia) within a 400 km2 arid zone catchment approx. 110km north of Broken Hill. Study focus: A comprehensive dataset of 10 s rainfall encompassing 17 rain gauges spanning over a decade (from 2013 to 2023) was meticulously analysed in combination with climate and stream levels and supplemented by daily camera images of the creek. New hydrological insights for the region: 64.6% of the rainfall flows to the creek, with the remainder lost before reaching the creek. Within this 64.6%, there were 67 individual flow events, comprising 47.7% of rainfall (35 events) associated with fronts and 16.9% (32 events) linked to local cumulonimbus storm cells. A fundamental characteristic of these flow events is their very rapid response, which appears to be independent of antecedent moisture content. The spatially averaged intensity of rainfall events experienced an approximate 200% increase, rising from 1.6 mm/h in mid-2013 to 4.8 mm/h by mid-2023. This noteworthy change is attributed to climate change. Despite the projected decrease in overall precipitation for the region, this observed rise in intensity aligns with the broader trend of global warming accelerating the water cycle. [Display omitted] •67 individual storm events produced runoff with 32 from storms, the balance from fronts.•Frontal rainfall well distributed across the area accounting for 47.7% of rainfall.•Average storm intensity increased from 1.6 to 4.8 mm/h over the ten year period.•64.6% of rainfall generated flow in the creeks and the balance is lost to percolation.•Runoff generation occurred independent of antecedent soil moisture content.