From Floods to Droughts

The Yangtze River is the longest river in Asia and the third longest in the world. Its basin is home to over 400 million people. It contributes significantly to China’s agriculture production as well as the industrial sector by providing essential mineral resources such as iron ore, coal, copper, phosphorus, gold, etc., near the cities of Wuhan, Chongqing and Sichuan province. It transcends domestic importance by being a powerhouse of industrial output, humming with activity of multinational corporations and major fashion brands. From tech giants like Apple to retail titans like Walmart, the basin provides a favourable atmosphere for industries. Surrounding the river’s banks are some 175 cities, contributing nearly half of China’s GDP. 

However, As China’s economy develops, pollution in the Yangtze and its lakes has multiplied, particularly sourced from agriculture and industries. Climate change has further exacerbated this, altering precipitation patterns and making them more erratic, with rainfall events more interspersed with longer dry periods. 

Before the 2020 floods, which impacted more than seven provinces, causing economic damage of more than 40 billion Yuan, several government officials and Chinese papers had warned of worsening extreme weather conditions and flooding in the basin due to climate change. Several meteorological reports revealed a gradual increase in air temperature precipitation in the upper Yangtze River, particularly in the source region, and an increase in extreme climate events in the middle and lower parts of the Yangtze River. According to these reports, intense reclamation of wetlands along the Yangtze hampered the basin’s ability to absorb floods. 

This article deals with the case of the 2022 simultaneous flood and drought situation in the Yangtze River basin caused by climate change. Further, it analyzes the critical role of infrastructure in tackling the flood and drought-like situation in the region by examining the role of the Sponge City initiative, cloud seeding, and water-transfer system as disaster control measures and analyzing their effectiveness in flood control and drought relief measures. 

The 2022 Flood & Drought

Between 11 and 20 August 2022, the north-western region of China experienced intense flooding and heavy rains. Flooding and mudslides raged down the slopes in mountainous areas of Datong Hui and Tu Autonomous County in Qinghai. More than six thousand residents were affected, with at least sixteen people killed and thirty-six missing. The heavy rain, called the ‘mountain torrent’ by the authorities, had also triggered floods in Zhongyang County in Shanxi and Sichuan. 

On the other hand, Yangtze basin experienced severe drought in seven northern and central China provinces, with temperatures reaching 40 degrees Celsius. It led to infrastructure damages like cement roads cracking under extreme heat in Henan. as well as reduction in crop yield and affected drinking water supplies, with around 36,700 hectares of crops affected. Six of the thirteen major grain-producing areas were affected during critical periods of crop growth. The drought also stressed urban and rural water supply since the small scattered water supply projects that relied on small reservoirs or mountain sprigs dried up. At the peak, 4.99 million people experienced difficulties accessing drinking water. Due to the persisting low level in the Yangtze River, the transport waterways from Anqing to Wuhan and from Wuhan to Yueyang were also closed. Since the hydropower capacity plummeted due to drought, areas such as Sichuan, where 80% of the electricity is sourced from hydropower, suffered. The extreme heat lasted for 79 days, the longest since 1961, and the intensity was also the highest on record.

The troubling pattern that can explain the above instances, has emerged in recent years: a persistent cycle of extreme heat accompanied by flooding at in other parts. The extreme heat leads to the formation of a heat dome, which draws moisture into western areas and unleashes torrential rain, exacerbating flooding as temperatures soar. This phenomenon is further compounded by the unequal distribution of precipitation, which primarily occurs within the two rainy belts in the north and south, leaving the middle reaches of the Yangtze River with scant rainfall. The overarching culprit is the melting of glaciers, affecting the Yangtze, Mekong, and Indus Rivers, causing warming temperatures and changing precipitation patterns. 

Whatever the causes, such extreme weather and climate events have become increasingly frequent, severe, and widespread. Their economic costs have been rising, with China losing around 13.13 billion dollars in 2022 from natural disasters alone. These instances further raise questions about China’s food and energy security, with the majority of its rice and wheat growing regions, as well as significant cities affected by extreme temperatures while facing acute water shortage, pollution and multiple Chinese provinces imposing power cuts as cities struggle to cope up with electricity demand surge in the event of such calamities. 

Infrastructure: Adaptation and Development 

In response to the challenges stemming from natural disasters, particularly floods and droughts, China has undertaken ambitious infrastructural projects and implemented innovative strategies to mitigate their impact. 

1.     Damming & the South-to-North Water Diversion program

The damming campaign has helped control floods and droughts, also providing a renewable energy source for the provinces along the Yangtze River. It was undertaken in response to frequent devastating floods in the basin. The resulting campaign led to the construction of over 60,000 dams along the Yangtze and its tributaries, the biggest being the Three Gorges Dam, whose reservoir was used to divert water to the drought-hit areas downstream. These water management projects have gained momentum in recent years owing to the South-to-North Water Diversion program, which aims at strengthening the national water grid. The multidecade, $62 billion Project is being built to channel 44.8 billion cubic meters of fresh water each year from the Yangtze River in southern China to the Yellow River Basin in arid northern China through three canal system – the eastern route through the Grand Canal, The Central route from the Han river (a tributary of Yangtze) via the Grand Aqueduct to Beijing and Tianjin and the Western route which draws water from the western Himalayan region to supply water to provinces like Qinghai, Gansu, Shanxi etc. located in the upper and middle reaches of the Yellow river in the north.

Building the western route for water diversion in China faces growing scrutiny. Environmentalists and scientists warn of potential social and environmental issues. Large-scale projects like the Shuotian Canal (located in Tibet) and the proposed Red Flag River diversion would traverse earthquake zones and mountains, raising concerns about triggering seismic activity, landslides, and other environmental damage.

Criticism extends beyond the western route. Some argue that existing dams, particularly the Three Gorges Dam, may not be as effective in flood control as claimed. While authorities say the dam reduces flood peaks, minimizes economic losses, and lowers casualties during heavy rains, critics point to data showing historically high-water levels persisting in the Yangtze and its lakes. This suggests the dam may not fully achieve its flood control purpose. Furthermore, critics highlight the ecological consequences of these dams. Increased pollution has reduced water quality and accelerated eutrophication (excessive nutrient buildup), leading to a decline in fish populations and overall aquatic biodiversity.

2. Cloud Seeding & the Tianhe Project

China's scientists are looking beyond the controversial western route for water diversion. Proposed in 2013, the Tianhe project, also known as the world's largest weather modification system, offers an alternative solution to drought in northern China. This ambitious project aims to create 5-10 billion cubic meters of additional rainfall annually by manipulating glaciogenic cloud systems (clouds formed by the rise of moist air over mountains).

Cloud seeding, a technique employed in the Tianhe project, is not new to China. Every city has a local cloud-seeding plan, utilizing silver iodide and drones to induce rainfall during droughts. In 2022 alone, cloud seeding efforts involving airplanes and rockets reportedly generated an impressive 8.56 billion metric tons of additional rainfall in the Yangtze River basin.

However, cloud seeding has limitations. Its effectiveness diminishes during extreme heat events due to the weak influence on summer clouds. While it can provide temporary relief during water shortages, its long-term efficacy and impact on the environment remain unclear. Additionally, it doesn't address underlying issues like the depletion of groundwater reserves in northern China.

3.     The Sponge City Project (SCP)

The "Sponge City" concept, introduced in 2013 by Professor Kongjian Yu, offers a revolutionary approach to urban water management in China. Unlike traditional impermeable cityscapes, these "sponge cities" function like, well, sponges. They absorb rainwater through increased green spaces and permeable surfaces, allowing for natural filtration by the soil and replenishment of urban aquifers. This captured rainwater can then be extracted and treated for city water supplies.

This concept has materialized in the Sponge City Project (SCP), a 2015 initiative by China's Ministry of Finance, Housing & Urban Development, and Water Resources. The SCP tackles urban flooding, water pollution, and scarcity by aiming to equip 80% of metropolitan areas with sponge-city features by 2030 and recycle at least 70% of rainfall. Key strategies include increasing green spaces, reducing impermeable surfaces, and utilizing rainwater capture techniques like rooftop collection and bio-retention systems.

The central government actively supports the project, allocating billions of dollars to aid 30 pilot cities. Wuhan exemplifies this transformation, with projects like the Stormwater Park serving as a model for other municipalities. Additionally, the Garden Expo Park, built on a former landfill, demonstrates successful implementation by utilizing existing infrastructure like rainwater gardens to collect and purify rainwater, minimizing costs.

To ensure effective local implementation, China’s ministry of housing and urban rural development played a key role in overseeing Sponge city construction. This included setting standards for building these urban water management systems, along with local water resources and urban planning departments. It also established how the effectiveness of these projects would be assessed. This assessment was divided into three main components: water ecology, water safety, and water environment. Each component has specific indicators, like impact on natural water areas, flood control, wastewater management, and water quality. The effectiveness of each component was evaluated through a combination of monitoring data and simulations to ensure all essential aspects are considered. 

However, there are significant gaps that still exist in the implementation of such sponge cities - 

1. China's Sponge City approach faces challenges in achieving truly comprehensive urban water management. Firstly, planning often lacks a holistic approach, neglecting to consider multiple objectives and integrate various water management measures. Additionally, insufficient collaboration between water and spatial planning experts, alongside a lack of stakeholder engagement, hinders the creation of additional value from these projects. Furthermore, the current approach compartmentalizes the five water topics, failing to capitalize on potential synergies for improved water resource management. Moreover, current planning lacks methods to build in resilience for future changes and integrate everyday values like aesthetics and recreation. Finally, sponge measure sizing relies on the VCRa ecological indicator, which has limitations and overlooks quantified storage capacity crucial for flood protection and drought mitigation.
   
   
2. These water management designs were based on rainfall patterns three decades before 2014. They were insufficient to address the intensified impacts of climate change we see today. For example, in Beijing's Mentougou district, initiatives have focused on managing 75 percent of annual runoff since 2018, equivalent to rainfall of only 25.9 mm within 24 hours. However, the recent heavy rain in Beijing recorded a staggering 270.2 mm, indicating that the existing sponge city plan is inadequate to handle the extreme weather conditions driven by climate change. This has been seen in the above cases as well as in 2023, too. Although Chinese cities have spent billions of dollars, more is needed to deal with climate change. Mark Fletcher, a global water business leader at Arup, suggested that to deal with the uncertainty brought by climate change, one would need something at the next level, something like ‘Sponge City Plus.’ according to him, it is time that they integrate advanced technologies like AI and big data into urban planning for effective forecasting and infrastructure resilience with community education and preparedness. 

Conclusion

In conclusion, the Yangtze River basin presents a complex landscape of economic vitality juxtaposed with environmental challenges. The interplay of industrial growth, urbanization, and climate change has intensified the frequency and severity of natural disasters, notable floods and droughts, posing significant threats to both human livelihoods and ecosystems. China has responded with ambitious infrastructure projects and innovative strategies aimed at mitigating the impact of these disasters. The construction of dams, exemplified by the Three Gorges Dam, and the South-to-North Water Diversion program represent significant efforts to control floods and ensure water availability in drought-prone regions. Similarly, initiatives like cloud seeding and the Sponge City Project demonstrate China’s commitment to employing cutting-edge technologies and nature-based solutions to address water management challenges. However, despite these efforts, there are inherent limitations and challenges. Critics argue that existing dams may not fully achieve their intended flood control purposes and highlight ecological consequences such as pollution and biodiversity loss. Cloud seeding, while promising, faces uncertainties regarding long-term efficacy and environmental impacts. Furthermore, the Sponge city project, although innovative, encounters challenges in comprehensive urban water management and resilience-building, particularly in the face of rapidly changing climate patters. The recent instances of simultaneous floods and droughts underscore the urgency for more adaptive and resilient infrastructure resilience. Moreover, integrated approaches that prioritize stakeholder engagement, holistic planning, and consideration of multiple objectives are essential to address the multifaceted nature of water management challenges in Yangtze River Basin. In essence, while China’s existing measures represent significant strides towards disaster mitigation, continued innovation, collaboration, and adaptation will be paramount in effectively addressing the evolving threats posed by climate change in the region. Only through comprehensive and forward-thinking strategies can the Yangtze River Basin navigate the complexities of its socio-economic and environmental landscape while ensuring the well-being of its inhabitants and ecosystems.