Measuring stream pollutant loads across the Great Barrier Reef (GBR) catchment area (GBRCA) is challenging due to the spatial extent, climate variability, changing land use and evolving land management practices, and cost. Thus, models are used to estimate baseline pollutant loads. The eWater Source modelling framework is coupled with agricultural paddock scale models and the GBR Dynamic SedNet plugin to simulate dissolved inorganic nitrogen (DIN) generation and transport processes across the GBRCA. Catchment scale monitoring of flow and loads are used to calibrate the models, and performance is assessed qualitatively and quantitatively. Modelling indicates almost half (47%) of the total modelled DIN load exported to the GBR lagoon is from the Wet Tropics, and almost half of the total modelled DIN load is from sugarcane areas. We demonstrate that using locally developed, customised models coupled with a complementary monitoring program can produce reliable estimates of pollutant loads.

由于空间范围、气候可变性、不断变化的土地利用和不断发展的土地管理实践以及成本，测量大堡礁 (GBR) 集水区 (GBRCA) 的河流污染物负荷具有挑战性。因此，模型用于估计基线污染物负荷。eWater Source 建模框架与农业围场比例模型和 GBR Dynamic SedNet 插件相结合，以模拟 GBRCA 中溶解无机氮 (DIN) 的生成和传输过程。流量和负荷的流域规模监测用于校准模型，并对性能进行定性和定量评估。建模表明，输出到 GBR 泻湖的模拟 DIN 总负荷的近一半 (47%) 来自湿热带，而模拟的 DIN 总负荷的近一半来自甘蔗地区。