Dry riverbeds contribute a substantial share of carbon dioxide in a new estimate for Australia’s river network. The single peer-reviewed modelling study followed seasonal changes in flowing water and exposed beds, rather than assuming a fixed river surface. Regional emission patterns differed between tropical wet seasons and temperate winter rains, with sparse dry-bed measurements leaving broad uncertainty.
Dry riverbeds added an estimated 13.9 teragrams of carbon dioxide annually to Australia’s river carbon budget. The single peer-reviewed modelling study combined measurements of gases with maps of the drainage network, following seasonal changes in water surface and exposed beds. A teragram equals one million tonnes.[1]
For flowing rivers, annual carbon-dioxide emissions were estimated at 48.5 teragrams. The methane estimate was 0.28 teragrams per year. Methane diffusion and release through bubbles were calculated separately. Tropical rivers showed wet-season emission peaks, while temperate southern rivers peaked with winter rains. A relatively stable national total concealed those contrasting regional patterns.[1]
After data cleaning and aggregation, 798 sites supplied 1,875 observations for the carbon-dioxide model. Dry-bed fluxes came from only 14 sites and were extended across the network, leaving substantial uncertainty. The dry-bed category required at least 4 months of flowing water annually; it omitted standing pools and some exposed margins.[1]
Methane measurements were sparser than carbon-dioxide observations, limiting monthly modelling of its concentration. Short, extreme floods were another constraint on the monthly calculation. The estimate therefore describes a seasonally changing network using unevenly distributed observations, with uncertainty in gas exchange and surface area as well as concentration.[1]
