Editor's note: Floods have caused havoc in South and Central China, especially Hunan province. In Hunan's Ningxiang county alone, 44 people have been declared dead or missing since heavy rains began pummeling the county on June 22. Three experts share their views on the floods with China Daily. Excerpts follow:
Reducing the human and material impact
To prevent flooding, local governments tend to raise the heights of dikes, and mobilize large numbers of people during the rainy season to reinforce the weak points of the dikes so as to prevent them from collapsing.
However, economic growth-induced urbanization has exposed the weak point of this practice: After a majority of the able-bodied villagers migrated to cities in search of better-paying work, it became increasingly difficult to mobilize enough people to "defend" the dikes.
Besides, just one breach in a dike can allow large volumes of water to gush out and inundate nearby places in a very short time, causing huge destructions. As Ningxiang continues its fight against floods, there have been reports of several dike breaches causing deaths and destruction.
It's time we changed our approach to fighting floods. For example, East China's Anhui province has found a novel way to reduce the human impact and financial loss of floods. Local officials in the province have deliberately kept a section of some dikes lower than the rest so that after reaching a certain level excess water can flow out through the lower section of the dikes.
Indeed, the onrushing water will cause damage, but not as much as when a dike collapses. And since the dike will still be intact, officials will have ample time to evacuate residents and minimize casualties.
Cheng Xiaotao, a senior expert with the National Committee for Disaster Reduction
Reservoirs can play a much bigger role
Official data for 2013 show Hunan alone had 14,121 reservoirs, with many others along the Yangtze River that flows through the province. These reservoirs, if better managed, can play a much bigger role in fighting against and preventing floods.
Reservoirs prevent floods by "reserving" water during the rainy season and "releasing" it during the dry season. According to the rules of water management, reservoirs should release the stored water before the rainy season so that they can accumulate fresh rainwater. But by doing so, the reservoirs will harm their economic interests, because they can continue generating electricity by releasing water even during the rainy reason.
Therefore, coordination and supervision from the higher level are needed to make sure those managing the reservoirs release the stored water before the rainy season.
Of course, if the rainfall is exceptionally heavy, the reservoirs will have no choice but to discharge huge volumes of excessive water, in order to avoid major accidents. And since the discharged water could flood areas downstream, reservoir managements and local governments must maintain close contact, so as to evacuate residents in time to avoid casualties.
Zhang Boting, a senior researcher at the China Society for Hydropower Engineering
Vital to guard against secondary disasters
Of the 44 people declared dead or missing in Ningxiang, at least nine perished in a mudslide triggered by a heavy downpour on July 1. According to one witness, the mudslide was so sudden that it buried her neighbor's house before the occupant could escape.
Such cases remind us to be on guard against secondary disasters, that is, those triggered by heavy rainfall. Typical secondary disasters include landslides, mudslides and random house and bridge collapse.
It is almost impossible to prevent secondary disasters during heavy downpours. But to minimize their impacts, it is imperative that local governments take precautionary measures. On July 2, despite the rain-triggered massive mudslides in two mountainside villages in Yongzhou, Hunan province, about 2,400 residents were safely evacuated from the villages thanks to the precautionary measures taken by the local governments. It is advisable that all regions that receive heavy rainfall follow the example of the two villages.
Fan Xiao, a senior engineer with the Sichuan Geology and Mineral Bureau of Regional Geological Survey Team
