Rivers like the Chang Jiang, Huanghe, Zhujiang, Haiho, Hun and Huai transport increasing amount of nutrients (e.g. nitrogen, phosphorus) to coastal waters of China due to the rapid population growth and human activities on land (Yan et al., 2010; Shen and Kroeze, 2007; Qu and Kroeze, 2010). As a result, eutrophication occurs along the coastal waters of the Yellow Sea, East-South Sea and Bohai Gulf in China. Recent modelling studies (Qu and Kroeze, 2012) indicate that river export of nutrients may increase in the coming decades causing severe eutrophication problems along the Chinese coastal zones.
In October 2012, Peking University of China (PKU) and Wageningen University (WU) started a joint PhD research on river export of nutrients to coastal waters of China.
The main research objective is to explore trends in nutrient export by rivers to coastal waters of China. This will be done by developing and applying an integrated nutrient model aimed at identifying effective management strategies to deal with nutrient inputs in rivers and the coastal waters of China. We also aim to develop an appropriate indicator for assessing eutrophication in rivers and coastal waters and apply it to Chinese river basins.
We use the Global NEWS (Nutrient Export from WaterSheds) model as a starting point. This model quantifies river export of different nutrients (nitrogen, phosphorus, carbon, silica) in different forms (dissolved inorganic, dissolved organic, particulate) for the past (1970, 2000) and the future (2030, 2050) years. The model allows to identify main drivers and sources of nutrient enrichments in coastal waters (Mayorga et al., 2010; Seitzinger et al., 2010). Future estimations are based on the four Millennium Ecosystem Assessment scenarios (Alcamo et al., 2005).
We will develop and apply a Chinese version of the Global NEWS model. This model will estimate export of different nutrients in different forms to rivers and coastal waters for past, present and future years taking into account sub-basin characteristics, main drivers and human activities. The newly developed model will be validated based on available measurements. A sensitivity analysis will be carried out to determine factors influencing nutrient export to rivers and coastal waters. A scenario analysis will be done to identify effective management strategies to deal with nutrients in rivers and coastal waters of China.
We plan to develop an indicator for eutrophication based on the ICEP (Indicator for Coastal Eutrophication Potential) by accounting for ICEP for rivers (ICEPriver). The current indicator was proposed by Billen and Garnier (2007) and aims to determine the potential of rivers to cause coastal eutrophication (Garnier et al., 2010).