Water Sources of Upland Swamps in Eastern Australia: Implications for System Integrity with Aquifer Interference and a Changing Climate

Abstract

Temperate Highland Peat Swamps on Sandstone (THPSS) in Eastern Australia are Groundwater Dependent Terrestrial Ecosystems that occur in the headwaters of streams on low relief plateaus. Like upland swamps and peatlands globally, they provide base flow to downstream catchments. However, these swamps are subject to aquifer interference from mining and groundwater extraction and are threatened by urbanization and climate change. We collected winter and summer water samples from swamps in two highland regions of Eastern Australia. Water from the swamps was analyzed for hydrogen (δ2H) and oxygen (δ18O) isotopes and compared with rainwater, surface water and groundwater samples from the surrounding bedrock aquifers to identify likely swamp water sources. Radon (222Rn) was used as an environmental tracer to determine whether the swamps were predominantly groundwater or rainwater fed. Four out of five swamps sampled in the Blue Mountains had greater than 30% of water derived from the surrounding bedrock aquifer, whereas swamps in the Southern Highlands received less than 15% of water from the surrounding aquifer. The water sources for swamps in both regions are controlled by catchment morphology, e.g., valley shape. Understanding water sources of these systems is critical for the determination of likely impacts on THPSS from aquifer interference activities and a changing climate.

Characterizing the Water Storage Capacity and Hydrological Role of Mountain Peatlands in the Arid Andes of North-Central Chile

“…Isotopic analysis should be the next step in order to better characterize the hydrological functioning. Evaluation of groundwater or snowmelt contribution to streamflow is recommended [78,79]. These altitude peatlands are not only water consuming reservoirs, but also allow for mixing of water from different origins, such as the main water course, small mountain streams and groundwater from several sources [36,69].…”