Understanding flow intermittency in arid stream catchments is essential for managing and balancing ecological health and human needs. The duration of flows in higher order stream reaches of the catchment is dependent on several factors, including the duration and magnitude of flows in the headwater stream reaches of the catchment, the existence of instream dams and other blockages, and transmission losses or gains from the subsurface as water flows through the headwater stream reaches. While the former factors can be easily measured at the surface, quantification of transmission losses is notoriously difficult. This work aims to upscale point measurements of infiltration to estimate catchment-scale transmission losses in a mostly ungauged catchment. Specifically, we aim to estimate losses along first, second, and third order streams feeding into the main branch of the Pedler Creek near Adelaide in South Australia. Not only are the intermittent streamflows in this creek important to ecological health, but surface water infiltration to the underlying shallow groundwater system is used for stock and domestic purposes and economically valuable vineyards. During a one-week period in February 2018 (i.e. while the streambed was driest), over 30 km of the creek was traversed while continuously logging ground bulk conductivity using a frequency domain electromagnetic induction tool with an investigation depth of ~7 m. Hydraulic conductivity of the streambed was estimated at discrete points within the surveyed stream reaches using a three-dimensional active heat pulse sensing instrument, and from collected streambed soil samples. Stream reaches not covered by these measurements were estimated by comparing soil and land use characteristics against the measured reaches. Analysis of the findings is ongoing. Expected outcomes include reach and whole-catchment estimates of transmission losses and infiltration, and a better understanding of subsurface streambed dynamics throughout the catchment during intermittent flow events.