Interview with Ran Qihua: Will there be another catastrophic flood on the Yangtze River again after 22 years?

Although the regulation and storage capacity of the lakes and branch rivers alongside Yangtze River have improved over the years and flooding like 22 years ago is unlikely to repeat, the flood control capacity in many rural areas is still weak.

Photo by Xinhua

Photo by Xinhua

By CAO Linhua

Heavy rainfall over the past few months has damaged much of southern China. A high-level official of the ministry of water resources said on July 13 that water swelled above the alarm level on 433 rivers, 33 of which suffered flooding at an unprecedented scale.

The ministry of emergency management said that by July 10, 141 people had died or remained missing and 29,830 square kilometers of farmlands were underwater due to the flooding. The approximate financial loss caused by the continuous rain is expected to reach 69.6 billion yuan (US$ 9.9 billion)

But above all, many people, especially those who live near the Yangtze River, are wondering if they will see a repeat of the catastrophic flooding which occurred in 1998.

The horrible memories linger among many who experienced the disaster. 4,150 people died. 6.85 million houses were destroyed.

Jiemian News interviewed Professor Ran Qihua, head of the Institute of Hydrology and Water Resources of Zhejiang University on July 13 to ask his opinion on this important question. Will the 1998 floods happen again?

Another round of rain

JM: Since May, floods have hit many provinces in China, why did they hit such a vast range of areas?

Ran: The main reason is El Nino. It has resulted in more extreme weather. We could see that the rain started south of the Yangtze River in May and lingered on in an area for a long period of time. Continuous rain led to floods.

JM: Does it has anything to do with the worsened environment alongside the Yangtze River Basin?

Ran: I don’t think so. It is the environment that is being impacted by climate change, not the other way around.

JM: The ministry of water resources forecasted a rise of hydrological extremes in the basin this year in March. What would be the worst-case scenario according to your research?

Ran: Rain has lingered on along the basin for more than a month. It is always hard to predict the best or worst. The rain could continue for another month. But such a black swan event is beyond human capacity to prevent. There will be another round of rain in the Yangtze River Basin, but I’m not sure if the rain will also hit other waterways such as the Yellow River and the Huaihe River.

JM: Many regions have reached the maximum water level, what will happen if the rain continues for another month?

Ran: Extreme situation forces extreme measures, if that was to be true, we will have to consider flood diversions which will inevitably send the torrents into farmland and villages.

“Collective effort is needed”

JM: The Yangtze River’s water level is higher now than it was in 1998, but the damage so far is less severe compared with that year, why is that?

Ran: Since 1998, China has built up its infrastructures to hold back flooding. Now we have more controlled reservoirs near the Yangtze River where we can send the water. With the Three Gorges and reinforced levees downstream of the Yangtze, our capacity to impound water is much better than in 1998. Therefore, the damage of floods is significantly reduced.

Take Wuhan for instance, half of the city was submerged in 1998. But this time, people in Wuhan continue their daily routines, the only damage so far for them is that they can’t jog or take a walk in the parks alongside the Yangtze River.

The flood control infrastructure is playing a vital role in protecting cities and people in the face of such extreme weather.

JM: Is there anything we can improve in terms of the regulation and storage capacity?

Ran: Casualties are not that common when floods come nowadays. This indicates that we have better regulation and storage capacity to control the water. But there is still room for improvement. For example, how to regulate and store water, its impact on the animals, and can the water channels connecting the mainstream Yangtze and two major lakes, Dongting and Poyang remain unobstructed? These are all questions yet to be answered.

But the biggest flaw in flood control, in my opinion, is a lack of collective effort at the national administrating level. The most important thing for flood control is unified planning and dispatching.

Now, each province is still fighting their own battles. But floodwaters don’t care about provincial borders. We must see the upstream and downstream as a whole. The upstream will suffer flooding if a dam discharges too late, but if it discharges too early, we will find the downstream under a lot of pressure.

I think collective efforts from different provinces are crucial to the flood prevention course. Without such efforts, there is a risk of flooding caused by contradicting orders from different provincial authorities.

China has eight water resources commissions managing the eight major basins. But the Yangtze River is way too long, and one commission can hardly manage all dams and other infrastructures. The interests of the industry and administrative divisions are just two factors that block the centralized coordination.

Small dike, huge risk

JM: Many people call for the reinforcement of the dikes along small rivers and lakes, why can these places be Achilles' heel in flood prevention?

Ran: China invested heavily in infrastructures around major rivers and lakes and it makes total sense that they are the priority. Compared with the completed and advanced flood prevention infrastructure along the main streams, small rivers and lakes are often neglected. But as far as I know, China has also been sparing no effort to improve the dikes and levees around small rivers and lakes.

JM: Drought bothered China frequently in the 1970s and flood left deep marks on Chinese soil in the 1990s. But it seems both natural disasters are happening more and more frequently since 2000, why is that?

Ran: A common notion among the public is climate warming. But the academics would prefer to blame climate change for it is not simply growing hotter or colder. The change brings more extreme weather.

JM: Having said that the regulation and storage capacity of our lakes and rivers is better, many lakes are shrinking, and the riverbed of the Yangtze River is deepening. Will these phenomena influence flood prevention capacity?

Ran: The shrinking of lakes will definitely hinder the flood prevention, especially the areas near the lake, for the smaller a lake becomes, the less water it can store. As for the deepening of the Yangtze River riverbed, it is caused by the scour of discharged water from the Three Gorge Dam. The river can store more water since it is deeper now. The flood peaks on the Yangtze River in 2010 and 2012 were both higher than it was in 1998, but no major disaster happened. One of the reasons was definitely the deepening of the riverbed.

JM: What can we all learn from the floods?

Ran: We should leave more room for the rivers. Too often, we squish rivers into land for commercial use. Society needs more land to develop itself, but how to strike a balance between the numbers and the environment is worth pondering for the administrations.

We haven’t seen such heavy flooding in about ten years. But that doesn’t mean we don’t need water conservancy projects anymore. On the contrary, the projects are the reason that has brought us this far. I’m concerned that from individuals to the officials, many have started to neglect the importance of these projects. That can be dangerous.