Soon the surroundings in Silkeborg will be replaced with a subtropical climate in Guangzhou. For a 6-month stay Anders Nielsen, a PhD student from Department of Bioscience, AU, will work collaboratively with Chinese researchers from Jinan University and Nanjing Institute of Geography and Limnology, CAS. These researchers are also associated with the SDC and his stay will be supported by SDC. The aim is to achieve better understanding of the influences from land use management on water quality in a smaller reservoir (27 km2) located approx. 120 km from Guangzhou.
The water quality has deteriorated during recent years and blooms of bluegreen algae have been observed in some parts of the reservoir. This is critical for the public of the million city, Kaiping, who receives drinking water from the reservoir. By setting up a river catchment model, the aim of the project is to analyze which measures need to be taken to improve the current water quality status through changes in the present land use management.
This catchment is among the 3-4 to be selected for the training of master students and as focus areas for PhD and research projects within the SDC “Water and Environment” theme. The catchments will be distributed from north to south China and selected to cover different land uses and climates. The catchment model developed by Anders Nielsen and collaborator in China and Denmark will later be used in the education of master students and for other SDC PhD/research projects.
Within the selected southern catchment land use is very diverse, ranging from native forest to highly intensive farming, but at the same time, the land use is differentiated markedly between the five draining rivers. One river receives water from native forest, one from intensive duck – or pig – farming, and a third one is heavily influenced by rice farming. This creates a unique possibility to identify responses in water quality from the corresponding land use and thereby their specific impacts on the reservoir. However, one challenge in the project will be to mimic correctly the rice paddies in the model, and the process description might need to be adjusted based on experiences from other Asian studies. The local water authorities have shown great interest in the study and will contribute actively.
Climate change is an important part of the agenda for water quality managers because changes may influence or even exacerbate the deterioration of the reservoir water quality through several biological and biogeochemical processes in the reservoir as well as enhanced nutrient losses from the catchment. By comparison of results from the catchment study in China (subtropical) and another in Denmark (temperate) the project will also address the likely consequences of higher temperature and seasonal increased extreme precipitation events, which is the anticipated outcome of changed climatic conditions in Denmark.