Saltwater Intrusion and the Mary River Wetlands of the Northern Territory

Associated with most coastal river systems of the Northern Territory are seasonally and intermittently inundated floodplains and lowland catchments that form over 12,600 km2 of coastal wetlands. The Mary River wetlands are amongst some of the largest coastal wetlands and lie 100 km east of Darwin, the capital of the Northern Territory (Figure 1). Like much of tropical northern Australia, the Mary River experiences a monsoonal climate with most of the average annual rainfall of 1,500 mm falling in a distinct wet season between November and April. The dry season is marked by high evaporation rates with maximum temperatures still over 30°C but generally lower daily minimum temperatures than those experienced in the wet season. These wetlands are subject to natural and in some cases severe variation as a result of the highly seasonal and unpredictable nature of the climate (Finlayson et al. 1988).