Managing flows for river health in the Yellow River
The flow in the lower Yellow River is almost fully controlled by Xiaolangdi Dam. Here, there is an opportunity to tailor the available environmental water allocation to optimise river health.
The lower Yellow River has been managed for centuries, so the local managers are extremely knowledgeable about the way the river behaves. The health of the river has greatly improved in recent times, but now a group of Australian river health and environmental flow experts are working with local experts in the Yellow River Conservancy Commission (YRCC) in Zhengzhou to explore ways of refining the management to achieve even better results.
Dr Chris Gippel, Activity Leader for Yellow River Environmental Flows and River Health Pilot, explains:
The Yellow River is known as the Mother River in China, because thousands of years ago it was a key resource that nurtured the expansion of the northern Chinese civilisation from its cradle in Henan. The Yellow River also has a dark side, at times being referred to as China’s Sorrow because of the devastating floods that have ravaged the highly-populated lower floodplain.
The river is now contained within high dikes, and the flows are controlled by dams. While this has lessened the risk to people, managers must continue to balance the need to minimise flood risk, supply water to industry, agriculture and towns, enhance general river health, and ensure the health of the internationally important wetlands of the river’s delta.
The 1980s and 1990s were not a good time for river health on the lower Yellow River. Ongoing dry weather had reduced flows from upstream, and demands from water users overwhelmed the supply. The river repeatedly dried up, causing hardship for the people relying on the river, and also for the plants and animals that lived in and along its course. The national government and the YRCC took up the challenge.
In 1999, the construction of the Xiaolangdi dam allowed for more control of the precious water resource, and the river managers made a commitment that the river would never again dry out. They also formally allocated a proportion of the flow to achieving environmental objectives.
Since then, the river has never stopped flowing, sand has been scoured from the bed from annual flushing flows, the delta has benefitted from water delivery, water quality has continued to improve in many respects, the communities along the river have continued to prosper, and there have been signs of improved ecological health.
One outstanding issue on the lower Yellow River is how to measure the ecological health benefits from this tremendous effort to improve river management. Because the Yellow River is so important economically and socially, its health is not just about the health of the birds, fish, bugs and plants, but also the health of the flow-dependent human values, such as security of water supply, water quality, and flood protection.
The ACEDP project has devised a program of river health assessment that covers the ecological, physical, social and economic aspects of the river. Now the YRCC will be able to present a comprehensive picture of the state of the river, to demonstrate effective management, and to pinpoint where more attention is needed.
One of the areas of river management that this project is aiming to improve on is environmental flows. There is a long history of research on this topic in the lower Yellow River, and this is a good time to pull all that work together, carry out some new assessments, and recommend some options that will lead to improved ecological outcomes.
Local experts share knowledge with Dr Marcus Cooling and Yellow River Conservancy Commission (YRCC) members on their 700 km expedition down the Yellow River
The ACEDP team introduced the concept of the holistic assessment using a multi-discipline team. We took a 700 km expedition down the river from Zhengzhou to where the river enters the Bohai Sea. We met local experts along the way, and finished our trip with a workshop in Jinan, to compare notes, jointly decide what the objectives should be, and plan further work to close off knowledge gaps.
Since then, the river has been surveyed in some critical locations, and a hydraulic model developed for the entire river length. Hydrology, fish, vegetation, bird, geomorphology and water quality data have been analysed using a range of techniques, including analysis of remotely sensed data from the delta. Now we can make predictions about river health for different environmental flows options.