Strategies and Achievements of Waterlogging Control in Longshan Community, Linhai

Source: http://tnews.cc/06/ADOShowBigPhoto.asp?from=U204182

So if seawater unfortunately backs up onto the land, how should it be solved? This year the Water Resources Bureau reinforced the second line of defense -- the seawall -- raising the original seawall height to 2.2 m, a bit higher than the 2.1 m storm surge caused by last year's most severe Typhoon Soudelor, hoping to at least prevent this year's flooding. The work is gradually proceeding, and only a small part of last year's severely flooded Dongbo District and Xibo District remains unfinished. It is expected to be fully completed on the eve of the Mid-Autumn Festival, the peak flooding period.

(The above content comes from the deputy director of the Tainan City Water Resources Bureau)

Whether the Problem Has Been Successfully Solved

Every year, once a typhoon rages, it has an enormous impact on Longshan Community. Take Typhoon Dujuan as an example: when Typhoon Dujuan struck, Longshan Community flooded up to calf height, residents suffered unbearably, and many livelihoods and properties were ruined, showing that the old engineering works had not been effective. Once a power outage occurs, it is even worse.

During Typhoon Soudelor and Typhoon Dujuan, many residents complained that although pumping motors had been installed, they still could not function during a power outage. Mayor Lai Ching-te said: "Generators have been placed, so even during a power outage the pumping motors will not be affected, but the main reason is that the Xibo District work has not yet been completed, causing the water to rise more." Xibo District is expected to be completed this year at the Mid-Autumn Festival, so its effectiveness is still unknown.

As for how effective the solution to the flooding problem is, the deputy director said: "In Minguo year 94, Typhoon Haitang left the coastal areas of southwestern Taiwan, China all soaked in water. The main reason was that the sandbar had already silted flat at the time, causing storm surges and swells to drive straight in and pour back in endlessly; in Minguo year 104, Typhoon Soudelor's storm surge level was 2.1 m, which was 0.14 m higher than Typhoon Haitang's storm surge level of 1.96 m, yet the flooding problem was reduced considerably compared with when Typhoon Haitang came, because the storm surge and swells were blocked in the outer sea, preventing them from driving straight into the inland areas. So judging from this example, sand-protection works such as sand pumping and dike building have obvious effectiveness."

A Different Perspective

As for ecological sand-protection methods, the city government used methods such as woven-fence sand fixation, sand sausage bags, and space bags, but the village chief said: "These all failed. The bamboo or wooden stakes used in woven-fence sand fixation even pollute the lagoon. When a typhoon comes, these stakes may be blown into a mess by the typhoon, and once the tide rises, they will drift everywhere with the seawater, causing ocean pollution."

How to construct a sound engineering project that does not pollute the environment at the same time is a very important issue, so seeking other solutions is also worth our discussion.

Problems and Solutions

Not only are the ecological engineering problems in the earlier section worth our discussion; in the face of climate change and sea level rise, community flooding and its derived problems may also change accordingly. Existing engineering may be unable to cope with increasingly severe problems, and dikes cannot be raised forever, so communication, understanding and mutual cooperation between residents and officials must continue to be strengthened, jointly promoting the concept of community self-reliant disaster prevention and enhancing the community's disaster prevention capacity. At the same time, it can also unite community awareness and combine it with local culture and community characteristics, so as to achieve Longshan's development strategy of "production as the means, living as the goal, ecology as the foundation." And only when the community truly achieves the four stages of disaster management (mitigation, preparedness, response and recovery) can it truly touch the core of the problem and let the problem be readily solved.