Managing floods of the Changjiang (Yangtze) River in China
A group of Chinese scientists have come to the EPFL to participate in a workshop on the water management of a 1’808’500 km2 catchment basin, 43 times the surface area of Switzerland. They will apply the MINERVE model, developed at the EPFL for the Rhone River catchment basin, to that of the Changjiang (Yangtze) River.
Modern water management must be performed at the catchment scale. It requires a thorough understanding of the relevant meteorological, hydrological, and hydraulic processes, as well as the ability to adapt to anticipated developments. Models of these complex systems are needed to tackle common problems related to flooding and droughts. The same is true for the management of resources for electricity generation, drinking water supply, irrigation, etc. Therefore, river water management must rely on an approach that includes multiple objectives.
This challenge involves an integrated approach to the hydrological cycle, including spatial and temporal variations of precipitation and temperature, as well as operations on the hydraulic installations along the watercourse, while at the same time taking into consideration water quality, environmental impact, sediment transport, and climate change effects.
The Changjiang Water Resources Commission (CWRC) brings together the expertise needed to deal with this complex set of problems in the Changjiang (Yangtze) River catchment basin in China (6300 km on 1’808500 km2, or 43 times the surface area of Switzerland). Despite the large difference in scale between the Chinese and the Swiss cases, a transfer of knowledge and experience acquired in Switzerland in the field of integrated water resource management is planned within the context of Sino-Swiss cooperation.
The Changjiang (Yangtze) River
Water resources from the Changjiang River are very unequally distributed, both in time and space, leading to frequent floods in the wet season and problematic droughts in the dry season. Floods are the most devastating cause of natural destruction, even though, in recent years, droughts have caused considerable losses to agriculture. The construction and operation of large reservoirs, like that of the Three Gorges on the main watercourse, or that of Danjiangkou on the tributary to the Han River, provide a new degree of flexibility to the management of water resources in the case of extreme hydrological events, albeit with an increase in its complexity.
In this context, an adapted, multi-objective approach to managing the Changjiang River’s water resources is needed, not only to allow for harmonious socio-economic development within the catchment area, but also to respond to the effects brought onto the region by climate change.
The MINERVE project
Modeling complex hydrological systems is essential for the engineers in charge of managing the hydraulic installations and protecting the region against floods. Catchment basins equipped with hydraulic installations must, therefore, be monitored using a technological framework advanced enough to simulate the different processes involved. Such a framework was developed at the EPFL within the context of the MINERVE research project, which had as objective the prediction and management of floods in the Rhone River catchment basin upstream of Lake Geneva. The Federal Office for the Environment mandated the Laboratory for Hydraulic Constructions (LCH) at the EPFL (Prof. A. Schleiss) to organize a transfer of knowledge in the form of an educational workshop on the concepts and software solutions developed at the EPFL, as well as on their application to the catchment of the Han river in China (a tributary to the Changjiang River, 1’532 km on a 174’000 km2 area, 4 times the area of Switzerland), which would serve as a test case.
The MINERVE project has been underway since 2002, in collaboration with the Federal Office for the Environment (FOEN), the Department for Roads and Watercourses, the Energy and Hydro-Electric Power Department of the Canton of Valais, and by the Water, Soil and Sewage Department of the Canton of Vaud. The Federal Office for Meteorology and Climatology (MeteoSuisse) provided meteorological forecasts and the hydro-electric companies shared information pertaining to their installations. The scientific component of the project was entrusted to two research groups at the EPFL, the Laboratory of Ecohydrology and the Laboratory for Hydraulic Constructions, and to the Institute of Geomatics and Risk Analysis at the UNIL.
Sino-Swiss cooperation between the FOEN, the EPFL, and the CWRC
Many years of collaboration have led to a friendly and intense cooperative relationship between China and Switzerland, in particular in the context of a project that provides support for flood forecasting on the Changjiang river, that began in 2003. An agreement on sustainable water management and hazard prevention, signed in Shanghai on April 19, 2009 by Moritz Leuenberger, Federal Counselor in charge of the Department of the Environment, Transport, Energy, and Communications and Mr. Chen Lei, Minister of Water Resources of the People’s Republic of China, further underpinned the cooperation. May 2010 saw the organization of an educational workshop in Switzerland with experts from the CWRC that provided an opportunity to lay the foundations for an integral risk management approach on the Chiangjiang (Yangtze) River catchment. Two meetings were held between the CWRC and the FOEN, the first in Wuhan in September 2010 and the second in Lausanne in November of the same year, to further refine the goals of the cooperation.
The cooperation will continue in the context of an educational workshop, organized at the EPFL from the 9th to the 13th of January 2012, for a delegation of engineers from the CWRC. The intensive instruction will allow the Chinese delegation to return to China with an elaborate model of the Han River watershed. The cooperation will then carry on by distance to assist the further refinement of the model to higher levels of detail. The Swiss delegation will then return to China one more time to validate the progress made by their Chinese counterparts. Once validated, the model will be ready to be extended to the entire Chiangjiang (Yangtze) River catchment.
Translated from French by Jan Overney, ENAC