Yangtze River Basin - case study
Co-developing a seasonal rainfall forecast service for the Yangtze River Basin
The Yangtze River Basin is home to one third of China’s population, covers one fifth of the land area, and is a key agricultural region producing about 70% of China’s rice. A research collaboration between scientists in the UK and China has developed a seasonal rainfall forecasting service to help decision-makers and communities plan for extreme climatic events such as flooding.
Rainfall in the Yangtze region is dominated by the impact of the East Asian Summer Monsoon. Intense or prolonged periods of rainfall can lead to flooding, which can damage infrastructure and impact millions of livelihoods. The river also has hydroelectric dams that rely on the seasonal rainfall to produce electricity for provinces and major cities in eastern and southern China including Shanghai.
Managers of hydroelectric dams can alleviate flood and drought impacts and regulate electricity supply by controlling the river water level. To support these activities, having a forecasting system that provides advance information about how much rainfall there could be in the coming months is vital.
Through the Climate Science for Service Partnership China (CSSP China) project, scientists from China and the UK worked together to develop a climate service based on seasonal forecasting for the Yangtze River Basin. The scientists knew that rainfall in the region is linked to the El Niño—Southern Oscillation (ENSO) and strong El Niño events tended to lead to above-average rainfall in the Yangtze River Basin. They identified that the Met Office seasonal forecasting system had significant skill in forecasting the variability of the El Niño—Southern Oscillation (ENSO) and its impact on Chinese rainfall.
Turning science into a service
Identifying that these findings could help decision-makers and communities in the region plan for flooding and drought events, the researchers worked in collaboration with each other and with key users to develop a prototype service that delivers forecasts of summer rainfall for the Yangtze River Basin months in advance.
In late 2015, the project started to develop a prototype climate service based on seasonal forecasts of rainfall and river flow. The product was then trialled by collaborators at the China Meteorological Administration (CMA) and the water management organisations in the Yangtze Basin, including the Three Gorges Dam, whom CMA advise.
“It was an exciting moment to see one team of scientists identify the user need for an improved forecast service, while another team discovered that our seasonal forecast system had useful levels of skill in the region. The strong El Niño developing at the same time provided an ideal opportunity to develop and test a new forecast service.” Philip Bett, Senior Scientist at the Met Office.
The climate service was successful, with users highlighting how it had helped them develop flood control plans that prevented flooding and avoided agricultural losses. Subsequent delivery of the service in 2017 and 2018 was also successful and the researchers have continually evolved the forecast and the service in response to user needs.
Users requested more regional detail, with a need for information in both the upper and lower Yangtze regions to aid hydrological planning. Further scientific research identified how this could be achieved, and by 2019 the project had incorporated this into the forecast. The project has continued to develop over time and first forecasts are now issued from early February in response to user requirements for more preparation time ahead of the summer months. A further scientific breakthrough has since been incorporated into the service - the successful predictions of average June rainfall in the middle and lower Yangtze regions up to four months in advance.
“We developed a positive flood control plan, effectively stopping the flooding, and reducing the flood pressure on middle and lower reaches”. Feedback from a user of the seasonal forecast climate service.
Supporting the Sustainable Development Goals
Outputs from CSSP China support the UN’s Sustainable Development Goals (SDGs). The co-develop of a seasonal rainfall forecast service for the Yangtze River Basin particularly supports work towards goal 1 (no poverty), goal 11 (sustainable cities and communities), goal 13 (climate action) and goal 17 (partnerships for the goals). Find out more about how the Met Office supports the SDGs.