In the face of climate change and sea-level rise, the Da Nang government has given the go-ahead for the NetPlus Corporation to pilot a coastal flood early warning system for vulnerable coastal Nhu Nguyet Street in Thuan Phuoc Ward , Hai Chau District. The system is intended to monitor, inform, forecast and issue warnings for high tide flooding to alert authorities at local level along with relevant agencies to take quick action to protect vulnerable communities, as well as assist residents to stay safe and prepare for flooding events.

High tide flooded coastal Nhu Nguyet Street on the night of October 19, 2022, although there was no rain. Photo: H.H

In recent years, localized flooding has occurred several times after heavy rains have pounded Da Nang during high tide or sea level rise. High winds associated with tropical storms or tropical depressions drive large waves and storm surge on shore, causing flash floods in the city, especially historic, widespread flooding which occurred on October 14, 2022.

However, during evening and night hours of October 19, 2022, although there was no rain in the city, big waves and high tides due to the combined effect of the tropical storm No. 6 and the northeast monsoon resulted in flooding many coastal roads in Thuan Phuoc Ward, Hai Chau District. Accordingly, the water submerged some sections of the sidewalks, and it could even overflow and flood into some homes if the water level just needed to rise by 10-20cm. Due to lack of experience in response to high tides when it is not raining, authorities at local level were confused about what to do in order to help local residents to take necessary steps to protect their property from flooding as no high tide bulletins have been issued to them.

As a result, focus was on deploying personnel to deeply flooded streets to set up vehicle barriers to stop driving through deep water in order to ensure the safety of road users. Heed was paid to arranging personnel to monitor changes in sea level as well as arranging a standing force to be ready to respond to high tides and assisting local residents to prepare for flooding in an attempt to reduce the risk of possible damages.

Earlier on the night of September 27, 2022 and the early morning of September 28, 2022, due to the missing of a storm surge and tide early warning system for coastal communities, members of the national steering committee based in Da Nang that was designed to respond to typhoon Noru had to view images from the coastal surveillance system in order to observe seawater level during peak storm surge brought by the storm.

Mr Duong Van Tuan, the  Director of the NetPlus Corporation stressed the need for Da Nang to set up a storm surge and tide early warning system for coastal communities as widespread flooding occurred in Da Nang in 2022 due to the combined effects of storm surges and heavy rainfall. On the other hand, storm surge and coastal flooding depend on a number of factors. These factors include the intensity of a storm, its size, translational speed, angle of approach to the coast, landfall location, and the bottom slope at that location. Therefore, a storm surge and tide early warning system is really necessary for Da Nang as it uses real-time data to detect early signs of flooding so that authorities at local level and residents can prepare better for high tide flooding.

In its first phase, the storm surge and tide early warning system will consist of  monitoring station, warning station, and a server. The monitoring station will be located on an coastal area in Da Nang, and it is designed to continuously collect water level data and transmits it to the server every 10 minutes with the use of radio waves. The station will use solar panels with backup battery storage. The warning station will include loudspeakers and warning lights that will be installed on street lighting poles in residential settings and high-traffic areas to alert the public about the flooding in efforts to help mitigate flood risks. The station will access to the same infrastructure resources and power source with the city’s public lighting system.

In its second phase, the flood warning system will be expanded and connected with Regional and National Centres for Hydro-meteorological Forecasting. In addition, importance will be attached to developing software for this system to collect tide data in order to issue periodic storm surge warnings for intervals of 10 days, 7 days, and 3 days.

The Da Nang government issued its approval notice on March 31, 2023 to allow the NetPlus Corporation to set up storm surge and tide early warning system for coastal Nhu Nguyet Street on a trial basis.

Currently, the Da Nang Department of Natural Resources and Environment is working with relevant local agencies to select a suitable location for this system, and carry out related procedures to facilitate its installation and operation.

Reporting by HOANG HIEP – Translating by H.L