MARINA (Model to Assess River Inputs of Nutrients to seAs) is a downscaled version of the Global NEWS model for China, but with improved methods of accounting for animal manure and human waste, as well as with updated information for reservoirs. The model quantifies past and future trends in annual river export of nitrogen and phosphorus in dissolved inorganic and organic forms. MARINA is constructed to assess: (1) sources of nutrient pollution in rivers, (2) impacts of upstream human activities on downstream water quality, (3) effects of nutrient pollution on coastal waters (eutrophication potential), and (4) solutions to reduce nutrient pollution in rivers and coastal waters. The model performs these assessments based on human activities on land, while taking into account sub-basin characteristics and losses of nutrients during their transport towards the river mouth.
MARINA runs at the sub-basin scale for six main rivers in China that drain into the Bohai Gulf, the Yellow Sea, and the South China Sea (see figure below). Following the Global NEWS approach, MARINA also uses input data at a spatial resolution of 0.5° × 0.5°. Simulations have been performed for past (1970), present (2000), and future (2030 and 2050) years with an annual simulation time step. Similar to Global NEWS, the Millennium Ecosystem Assessment (MEA) scenarios were also used in MARINA to simulate nutrient export for future years. These scenarios account for the industrialisation of animal production as well.
One of the current developments regarding MARINA includes the improvement of the transport processes of nutrients within the agricultural systems in the model. To this end, a link is made with the NUFER (NUtrient flows in Food chains, Environment and Resources use) model that quantifies the nutrient use efficiencies of food chains in China, considering agricultural drivers in food production and consumption. Furthermore, efforts are made to utilise hydrological output data of the VIC model for MARINA.