Early warning systems (EWS) are integral to disaster risk reduction and climate resilience, safeguarding lives, property, and infrastructure against flood impacts. ISET has been collaborating with partners in Hue City (formally Thua Thien Hue province) to enhance the province’s EWS, with a key focus on integrating redundancy (i.e. built-in backup capacity) into its design. This approach addresses gaps in system reliability, and we are now beginning to see tangible results.
Hue – Where rain is a ‘specialty’
Hue City, located on Vietnam’s central coast, is highly susceptible to floods and storms. Twenty-five years ago, the city endured one of the worst flood disasters in the country’s history, leading to significant loss of life and property and which to this day continues to evoke troubling memories for many survivors. In legacy of this tragedy, the city has heavily invested in its disaster management system, enhancing financial resources, human capacity, infrastructure, and technologies, including for its flood forecasting and early warning system.
However, with storms, heavy rain and flooding are persistent challenges (with repeated serious and sometimes unusual storms and flooding events as recent as in 2020, 2022 and 2023). Amidst today’s urban development and climate change, Hue still struggles to keep its people and assets safe despite its investment efforts.
Blind spots in the EWS
Despite heavy provincial investments, our Flood Resilience Measurement for Communities (FRMC) studies revealed several gaps in Hue’s flood forecasting and EWS. First, rainfall and water level monitoring equipment sometimes lack reliability and data connectivity, reducing the speed and accuracy of flood forecasts. For example, the Kim Long and Phu Oc river gauging stations in Hue have become increasingly unreliable in recent years, frequently malfunctioning during heavy rains, compromising their critical role in reservoir operation management and flood warning.
Additionally, insufficient, aging warning equipment and outdated technology hinder communication with communities, especially vulnerable groups like the elderly and those in remote low-lying areas. Equipment failure and limited contingency planning for extreme events also pose challenges, as the system’s dependence on electricity and internet access means that service disruptions during floods can prevent critical warnings from reaching residents. For example, FRMC study results indicate that in many wards/communes in Hue, the loudspeaker systems depend on electricity to operate, yet major floods often cause power outages. Without generators or backup power options, the emergency alert system becomes ineffective during extreme events.
This poses significant risks, especially during prolonged or successive floods such as the October-November 2020 flood event. Without power, other communication channels—such as television, radio, and internet—are also typically unavailable. While cell towers may remain active, most residents lack power banks with which to recharge cell phones, resulting in reduced ability to receive or send critical messages.
The importance of redundancy
Building redundancy is an effective approach to addressing the identified blind spots in Hue’s EWS. Redundancy is a core aspect of resilience thinking, one of the “four Rs” alongside robustness, resourcefulness, and rapidity. It refers to a system’s capacity to continue essential functions during failures, thanks to built-in backups or spare capacities.
For flood EWS, redundancy might include multiple sensors for monitoring rainfall and river levels to cross-reference data for accuracy. In communication, redundancy means having multiple alert channels—like sirens, text alerts, radio, or local messengers—so that if one channel fails, others can still deliver warnings to affected communities. For building or community power, redundancy can include back-up generators or combined solar and battery systems. This layered approach helps to strengthen EWS reliability, making it more resilient in crisis situations.
Redundant systems are crucial in disaster-prone areas like Hue, where early warning equipment failures, disruptions to power, internet, or communication infrastructure are common during extreme floods. By building these backup systems and redundancies, even if some elements fail, the EWS as a whole can maintain essential functions, helping to prevent gaps in warning delivery and ensuring that communities are informed and can take timely action.
Closing the gaps
In collaboration with the Standing Office of the Steering Committee for Disaster Prevention and Control, Search and Rescue of Hue City (DRM Office), ISET has implemented several key improvements to enhance the city’s EWS, focusing particularly on redundancy and reliability.
In September 2024, ISET supported the installation of two automatic river water level gauges equipped with radar sensors and solar batteries at Da Vien Bridge on the Huong River and Phu Tu Bridge on the Bo River, strategically positioned near the existing Kim Long and Phu Oc stations. These gauges provide real-time backup data, helping to mitigate delays and failures at the Kim Long and Phu Oc stations, which have become more frequent, as demonstrated in recent years including during Tropical Storm Trami in October-November 2024. This addition has been instrumental in managing the province’s three major hydropower reservoirs–Binh Dien, Huong Dien, and Ta Trach–and ensuring timely community alerts.
In addition, two high-power, remotely operated sirens were installed in August 2024, providing far-reaching alerts covering areas within 5km of the siren. First used during Tropical Storm Trami, these sirens serve as a robust, last-resort warning system for Hue City. Recognizing its effectiveness, the provincial government has approved the expansion of this model for storm warning across all nine districts/towns of the province.
During Storm Trami, two siren clusters were operated to effectively warn people to stay off the streets and proactively respond to the storm. Similarly, during the flooding period following storm Trami, when the operation of Kim Long and Phu Oc stations was both interrupted for more than a day during heavy rain, the newly installed gauges [at Da Vien bridge and Tu Phu bridge] came to tremendous help for the operation of reservoirs and monitoring of flooding in the downstream areas of our province.
Mr. Le Dien Minh – Head of DRM Division, Hue DRM Office
In 2022, two smart flood warning towers were also installed in Trung Lang (Quang Thai commune) and Pho Nam A (Quang Tho commune). The towers send real-time flood data to the hydro-meteorological system and issue warnings through the widely used Hue-S app. Featuring sirens, rotating lights, and solar-powered 30-day battery backup, these towers are built to withstand floods, storms, and power outages. They provide critical alerts when other channels may be compromised. A private company, Watec, contributed half the cost of these installations.
Both the river gauges and the smart flood warning towers transmit real-time data to a web-based platform, which securely stores and makes the data accessible for analysis, visualization, and decision-making.
“When flooding happens, flood level data from the warning tower will be updated on the website of Quang Tho commune. We will also send updates to the village heads, who will inform people in their villages so they can take timely and appropriate actions. The data from the flood tower in Pho Nam A village can be used to predict flood level in other locations in the ward, so it will be useful not only to this village but other nearby villages in our commune too.”
Mr. Le Thanh Xuan, DRR official of Quang Tho commune
ISET also provided backup early warning equipment for communities and wards/communes in Thua Thien Hue. This support includes backup generators for powering loudspeaker systems during outages, portable power banks to keep community first responders connected, and portable loudspeakers for disaster response teams to notify households that may struggle to hear standard loudspeaker warnings. These tools help maintain communication even when primary systems fail.
For all provincially managed equipment, the DRM Office successfully secured annual budget allocations from the Thua Thien Hue provincial government for operation and maintenance. Similarly, local governments and communities have confirmed plans to ensure ongoing use of ward and commune-level equipment, reinforcing the redundancy that underpins system resilience.
“Being one of the most flood-prone provinces in Vietnam, our province needs robust and innovative measures to strengthen its flood early warning system. We really appreciate the project support for the river water gauges, the smart flood warning towers and sirens. They will provide us with timely data and help us deliver prompt warnings to the communities. We have acquired the People’s Committee’s budget allocation for the annual operation and maintenance costs of the installed pieces of equipment and similarly for all those that will be installed.”
Mr. Dang Van Hoa, Director of Hue DRM Office
Sustainability and moving forward
The improvements highlighted above demonstrate our approach of targeting multiple levels to effectively address community resilience needs. This includes a balanced mix of advanced, high-tech solutions alongside adapted low-tech measures, each serving a unique role in strengthening flood EWS in Thua Thien Hue province. In all cases, ISET works closely with provincial partners to ensure that the equipment and measures are fully integrated into the official system, promoting sustained effectiveness and long-term impact.
While these efforts represent significant progress, they are only initial steps in improving the province’s EWS. ISET has also been working on establishing a comprehensive flood database, which, among other functions, provides reference information for flood forecasting and supports the development of a flood parking map that identifies safe locations for vehicles during flooding. Additionally, ISET have delivered training on accessing and utilizing various sources of EWS information. In the coming years, ISET will continue collaborating with the province to refine early warning messages to enhance clarity and better meet community needs. ISET are also committed to identifying other gaps and implementing targeted solutions to address them. Strengthening the EWS and building climate resilience will require sustained, ongoing effort.
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This blog was originally published by ISET on January 6th 2025. You can view the original here.