The Yangtze River, the longest in Asia and the third longest in the world, has flooded its banks numerous times throughout recorded history. While analysis of the Yangtze River flooding patterns has increased over the years, due to improved modeling and instrumentation, flooding remains a highly unpredictable phenomenon. Flood forecasting remains a challenge and the frequency of flood events has grown over the decades due to climate change and human activities.
“The flooding of the Yangtze River has been a regular occurrence throughout history, particularly in its middle and lower reaches,” explains Professor Zhang, an expert in water resources engineering at Beijing University. “However, in the past 50 years due to increased development and changes in land use, flooding has become more common and severe.”
Since 1950, the Yangtze has flooded more than 30 times, causing human and economic losses amounting to billions of dollars. In 1998 and 2016 alone, the devastating floods caused losses estimated in excess of $2 billion each. Both floods also caused significant loss of human life.
The last 50 years has also seen a gradual increase in the magnitude of floods occurring. The 1998 and 2016 floods, for instance, saw record-breaking water levels, with the 2016 floods peaking at over 53 meters and the 1998 floods over 52 meters.
Further, The 2016 floods were reportedly the largest flood ever recorded on the Yangtze River since 1951. They lasted around 32 days and set a high-water record at the Three Gorges Dam and in several other gages along the river, causing extensive flooding in areas downstream.
“In addition to this,” points out Professor Zhang, “in some provinces along the River, there has been an increase of up to 30 percent in river margins. This increase is a contributor to flooding in many instances — especially when combined with effects of heavy downpours and high hydrologic levels.”
Clearly, the Yangtze River flooding is an ever-present danger on the lives and livelihood of people living in areas near it and the frequency of such occurences is increasing. Understanding the frequency of flooding is thus key to enabling preventive or protective measures in the region to be effective and timely.
River Modification Works
The Chinese government have implemented a number of measures to reduce the rish of flooding and its consequences. Such measures include the implementation of a regional flood prevention system, the construction of dikes along the river and other flood control infrastructure, and river modification works.
The most recent river modification works on the Yangtze River, in Baihetan Hydropower Station, were designed by a team from the Nanjing Hydraulic Research Institute. These works were completed in June this year and are aimed at mitigating the effects of floods to a certain extent. They are expected to decrease flood levels in the middle reaches of the Yangtze River by more than 20 percent.
In addition to its modification works, the Chinese government’s policies regarding land use in the upper river basin also have a major influence on water run-off and flooding in the region. Policies such as improved forestry, soil conservation and vegetation restoration have been demonstrated to have a beneficial impact on flood control in both the upper and middle reaches of the Yangtze River.
Improved Flood Forecasting
Flood forecasting is critical to many areas along the Yangtz River, particularly in its lower reaches. To this end, the Chinese government has invested heavily in the development of an improved flood forecasting system.
This system links together observation networks, hydrological forecasting, and satellite data to provide timely warnings of potential flooding events. In addition, numerical simulations are also used to improve the accuracy of the forecasts. Other measures such as telemetry are also employed to monitor the water levels in the river.
The improved forecasting system has enabled residents to be better prepared for the floods. In addition, the Chinese government is reportedly investing further resources in the development of systems to manage floodwater and to better allocate water resources in the region.
Summary
In summary, the frequency of floods of the Yangtz River has increased over the past 50 years due to the effects of climate change and human activity. Dozens of floods have caused billions of dollars worth of damage in the region and many have resulted in loss of life. To mitigate the impacts of flooding, the Chinese government has implemented a number of river modification works and is investing heavily in improved flood forecasting.
Large-Scale Flood Prevention Plans
In order to reduce the risk of flooding in the Yangtze River and the resulting human and economic costs, the Chinese government has implemented large-scale flood prevention plans. This includes the implementation of a regional flood prevention system, construction of dikes along the river, river modifications works and improved flood forecasting.
The flood prevention system consists of a network of dams, dikes, protective embankments and pump stations, which allow for flood mitigation. Flood-proofing measures are also put in place to protect people, animals, plants and property in areas close to the river.
In addition to this, the Chinese authorities have also begun the process of constructing a huge 18-kilometer-long tunnel underneath the Yangtz River to control floodwaters. This will not only provide control over the river’s water levels, but will also relieve pressure on the river’s levees and dikes.
The construction of these huge engineering projects has no doubt had a positive impact in reducing the risks of flooding and recent research suggests that this may indeed be the case.
Economic Impact of Response Measures
Of course, with any large-scale flood prevention measures, there are associated economic costs. The Chinese government has invested billions of dollars in river modification works and other flood prevention measures. In particular, recent works like the huge 18-kilometer-long tunnel have cost billions of dollars, prompting many to call into question whether such measures are justifiable and cost-effective.
Research conducted by Beijing University suggests that the economic costs of flooding are far greater than the costs of flood prevention and mitigation when considering the impact on both human lives and property. The research has also shown that if appropriate preventive and mitigation measures are taken, then the impact of flooding can be reduced, thus preventing or reducing the economic and social losses suffered by communities in the region.
In conclusion, the Yangtz River has flooded regularly throughout its history and the frequency of floods has increased in the last 50 years. Floods can cause significant destruction and loss of human life, prompting the Chinese government to invest in large-scale flood prevention measures to reduce the risk of flooding. These measures come with a high economic cost, but the benefits of reducing the impacts of flooding still outweighs those costs.
Environmental Impact
The construction of dams and other large-scale engineering projects along the Yangtze River and its tributaries have had significant environmental impacts on the region, both positive and negative. Whilst such projects certainly help to mitigate flood risks, they can also have a deleterious effect on the ecosystems in the area.
The construction of the massive 18-kilometer-long tunnel, for example, has had a significant impact on the environment, both during and after the construction process. These impacts have included air and water pollution and disruption to the local ecosystems. In addition, the construction of such a project has also had a major effect on the cultural heritage of the region, as the area is home to several ancient cultural relics.
In order to mitigate the environmental impacts of the flood prevention projects, the Chinese authorities have implemented measures such as land reclamation, agricultural land management, and floodplain restoration. These measures aim to restore the local environment, improve soil fertility and protect against soil erosion. In addition, the Chinese government has also implemented monitoring systems to measure the environmental impacts of the projects.
Whilst the environmental impact of the flood prevention projects is undeniable, their positive effects far outweigh the negative. Indeed, these projects have enabled the Chinese authorities to reduce the risk of flooding, protect local communities from serious damage and prepare for the future.
Reports and Recommendations
Many reports have been conducted on the Yangtz River and the efforts of the Chinese authorities to reduce the risks of flooding. A report by Beijing University in 2018 concluded that, whilst the Chinese government has done well to reduce the impact of flooding, there is still much to be done to improve the safety of local communities and infrastructure.
The report noted, for example, that whilst there has been significant investment in flood prevention projects, more needs to be done to improve flood monitoring and forecasting, and to strengthen the existing dikes and embankments. In addition, the report also recommended that more needs to be done to ensure the sustainability of the projects, both in terms of their long-term financing and their impact on the environment.
The Chinese government has taken on board many of the recommendations outlined in the report and is continuing to invest in further flood prevention and mitigation projects. The government has also pledged to continue to strengthen existing dikes and embankments and to improve its flood monitoring and forecasting systems.
It is clear that the frequency of Yangtz River floods is likely to increase in the future as a result of climate change and human activities, and that the Chinese authorities must continue to invest in flood prevention and mitigation measures. Improved flood monitoring, forecasting, and engineering works are all essential in further reducing the risks of flooding in the region.
