Vegetation and stream pattern as indicators of water movement on the Magela floodplain, Northern Territory

Abstract

Magela Creek is a hydrologically complex waterway which drains Australia's two largest uranium deposits, carries a pastoral and tourist industry and has been proposed for inclusion in a national park. In this study, the vegetation and stream patterns of the floodplain are described and are used as indicators of surface water movement through the system. The Magela floodplain was found to be a freshwater lagoon, enclosed at its outlet by, the floodplain of the East Alligator River; the vegetation types are direct indicators of water depth within the lagoon. The capacity of the lagoon is approximately 60 × 106 m3, the average daily input during the wet season is approximately 3% of the lagoon volume and during the dry season the lagoon dries out to approximately 5 × 106 m3 of perennial swamp. The lagoon is maintained by the East Alligator River and so its hydrology must not be studied in isolation but in relation to the larger system to which it belongs.