Oral Presentation Freshwater Sciences 2023

Identifying intermittent river sections with similar hydrology using remotely sensed metrics (#40)

Thiaggo C Tayer 1 , Leah S Beesley 1 , Michael M Douglas 1 , Sarah A Bourke 1 , Karina Meredith 2 , Don McFarlane 1
  1. University of Western Australia, Perth, WESTERN AUSTRALIA, Australia
  2. Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia

As the human population grows and the demand for freshwater intensifies, river systems previously overlooked for water production are increasingly being earmarked for development. Many of these rivers are intermittent or in remote locations, and most are insufficiently instrumented and poorly understood, even though sustainable water resource development and the effective management of these systems depend on a thorough understanding of their hydrology. Remote sensing of surface water has been posed as a viable method for describing the morphology, resilience and fragmentation of river hydrology, much like metrics generated from discharge data. The low cost and increasing frequency and quality of spectral images mean that this approach has great potential to characterise hydrology at fine scales across large areas. However, the approach remains largely untested, with previous research only examining a few river sections. This study aimed to characterise a hydrologically diverse 400 km reach of an intermittent lowland river using remotely sensed metrics. We used multidimensional clustering to identify river sections with similar hydrology and examined their spatial arrangement along the river to gain insights into broad-scale hydrologic patterns. Metric clustering revealed four hydrological zones that spanned a continuum from highly intermittent to highly persistent. Spatially, zones were at the scale of pool-run/riffle geomorphic units that alternated along the study area. Density maps of hydrological zones revealed that the mid-section of the study reach had higher persistence and longitudinal connectivity, a finding that aligned with a pre-existing groundwater discharge map generated from field sampling of environmental tracers. The ability to map hydrology continuously along the length of a river is a significant advance compared to a gauged approach, which can only classify hydrology at a single point. Continuous classification increases our ability to describe spatial patterns in hydrology, which could markedly affect how a river is managed.