‘IT’S NOT TOO LATE’: Experts warn of flood risks due to climate change

By Joseph B.A. Marzan

 

Local and national experts on environmental and social sciences on Tuesday warned that the city and province of Iloilo are some of the worst places in the Philippines at risk of feeling the impacts of climate change in the next years.

The warning was raised during the first of the Flood Resilience Summit, a four-part webinar series centered on “Reducing Iloilo’s Risks of Flooding”.

The series was organized by the University of the Philippines Visayas (UPV), in partnership with the city and provincial governments of Iloilo.

The webinar series is a UPV-led initiative to help the city and provincial governments to lessen the risks of flooding, especially in high-risk areas.

Iloilo City was one of the worst-hit by Typhoon Frank (International name: Fengshen) in mid-2008.

The National Disaster Coordinating Council (NDCC) stated in a report released on July 31, stated that as of a week earlier (July 24), the storm affected up to 261,355 persons, with 1,478 houses totally damaged and 4,978 houses partially damaged, in Iloilo City.

The damages to the city were estimated at P6.4 million in school buildings and P19.5 million in other properties and facilities, based on the report.

Iloilo province saw 782,325 affected residents, with 27,063 houses totally destroyed and 56,156 houses partially damaged.

Damages in the province were estimated at P472.5 million in roads, bridges, and other structures, P52.5 million in school buildings, P31.5 million in electrical facilities, and P14.1 million in livestock.

The report consolidated numbers in the city and province to 105 casualties, and 717 injuries.

A portion of the webinar series centered on “Understanding Flooding in Iloilo”, and featured speakers Dr. Fernando Siringan and Dr. Mahar Lagmay from UP Diliman, Dr. Francia Avila of the Manila Observatory, and Dr. Gay Defiesta and Prof. Jessica Dator-Bercilla of UPV.

In his message, UPV Chancellor Dr. Clement Camposano said the optimism from the measures to counter the current coronavirus disease 2019 (COVID-19) pandemic were “obscuring” the serious threat of disasters.

Camposano mentioned the recent flooding in the Cagayan Valley due to Typhoon Ulysses (International name: Vamco), which struck the region and other parts of the Philippines between Nov. 9 to 13.

The National Disaster Risk Reduction and Management Council, the NDCC’s successor since 2010, reported 213 incidences of flooding across the country – 76 from the Cagayan Valley Region, from “Ulysses” alone.

“There is confidence that despite the challenges, the worst being the current pandemic and its debilitating impact on the local economy, Iloilo will continue to surge ahead. This optimism, however, obscures a serious threat—the peculiarity of our geography, and the way with which communities have historically interacted with the physical environment—render this hive of economic activity highly susceptible to catastrophic flooding,” Camposano said.

He also cited the inevitability of floods, saying that the focus should be on how Ilonggos can reduce their impacts in the communities.

“Floods will come, and they will make life difficult especially for the most vulnerable among us. The only question is how effectively we Ilonggos can reduce the impact of floods on our communities,” said Camposano.

 

 

LEARN FROM MISTAKES

Dr. Siringan of the UPMarine Science Institute in Diliman shared a study by one of his students on the effects of river channel constrictions, widening, and deepening on flood stages of the Marikina River.

The Marikina River is the largest tributary of the Pasig River and stretches through Pasig City, Quezon City, and San Mateo and Rodriguez in Rizal province.

Marikina City is one of the most flood-prone cities in the country due to its low elevation of 15 meters above sea level, according to data by the De La Salle University’s Center for Complexity and Emerging Technologies.

Constrictions are narrow portions of rivers which might be either natural or man-made.

In many places, constrictions are man-made, and according to Siringan, urbanization is a man-made driver of constrictions, such as in rivers of Metro Manila.

Velocity increases in these constrictions but there would be a decrease in discharge of water upstream causing buttressing and an eventual increase of the water level in the upstream channel.

The study mentioned by Perez examined the effects of changes in channel width between “Ondoy” and the 2012 “Habagat” monsoon rains and studied riverbed morphology using a morphodynamic model to examine the effects of constrictions in the Marikina River.

The ultimate result of the study was that widening removal of constrictions increases the channel capacity, being a more permanent feature in reducing flood stages.

This was in contrast to dredging, which could be a “waste of funds”, as a dredged channel may be filled up by even just a single flood event.

During the talk, Siringan remarked that Iloilo City “still has the opportunity to learn” from the constrictions in the Marikina flood plains.

Using satellite images of the Iloilo River area, Siringan demonstrated low-lying areas with two large sandbars which are products of natural accretion, former shoreline positions which blocked the flow of the river and shifted the river mouth to the east, leaving behind what might have previously been a fan delta.

He warned that those low-lying areas should not be developed as they are part of the flood plain of the city.

“Iloilo still has an opportunity to learn the mistakes of Marikina. It is not too late. Although it is now a well-urbanized place, [it is] still not like Metro Manila and the developments on the side of the Marikina River, where the flood plain has almost disappeared,” said Siringan.

 

 

MAINTENANCE OF SYSTEMS

Dr. Mahar Lagmay presented a study conducted by his team on a geological perspective of the flooding from “Frank”.

Lagmay is currently the director of the UP Resilience Institute and spearheads the Project NOAH (Nationwide Operational Assessment of Hazards), based at the UP National Institute of Geological Sciences in Diliman.

The study was based on the amount of rainfall measured by recording stations of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), in Dumangas town and Iloilo City, from June 18 to 22, 2008.

It also looked at some alluvial fans in Iloilo City, which are in the foothills of mountain ranges in the province.

Alluvial fans are triangle-shaped deposits of sedimented materials, created usually by interactions between flowing water and larger bodies of land such as mountains, hills, or canyons.

Project NOAH was previously under the Department of Science and Technology, with the previous administration investing in Light Detection and Ranging (LiDAR) technology for early detection of rains and possible flooding.

This was, however, taken over by UP Diliman after President Rodrigo Duterte defunded the project in 2017.

Lagmay, who had been at the center of Project NOAH since its inception in 2012, urged the city and provincial government to continue coordination on the maintenance of parts of the project.

He mentioned that the hydromet sensors and rain gauges were important to detect rainfall as early as 3 to 6 hours before they hit land.

More than 1,000 automated rain gauges (ARG), automated stream gauges (ASG), and automated weather stations were installed by Project NOAH across the country.

Based on Project NOAH’s records, according to Lagmay, 15 disasters had been averted because of this system.

“In the span of 8 years, we found that the most critical data that is needed to do the early warning 6 or 3 hours in advance are the sensors that have been placed along river systems, and rain gauges that have been placed in the mountains in different places of a particular region or community. I would like to recommend them to be always operational because they provide eyes for us in the mountains, along rivers, and in flood areas especially in flood plains. They’re not just valuable for academics, they save lives,” said Lagmay.

Lagmay also shared flood scenario maps, with up to 100-year return rain events, developed by the DOST via Project NOAH in partnership with several state universities and colleges, which included the Jalaur River Basin in eastern Iloilo.

These scenarios were presented in terms of the flood depth level as well as hazards levels that included the velocity.

They were made to assist in flood planning for communities to avoid intense flooding in the future.

Another project shown by Lagmay was Project Rebuild, done with the United Nations Development Programme, which was aimed to advance capacity and competency of key local stakeholders in cities and municipalities surrounding the Jalaur and Cagayan River Basins on Climate Change Adaptation (CCA) and Disaster Risk Reduction (DRR).

The findings from Iloilo borne out of these projects were used by Lagmay and his team to develop and improve programs across the country, including Metro Manila.

He also shared their current activity developing flood resilience maps with UPV and help in mangrove planting work in Leganes town with partners from Iloilo City.

Lagmay said that in planning for disasters, complex hazards must be considered, and that all sectors “must have a place in the table”.

He mentioned the current COVID-19 pandemic being of great consideration during disasters at this time.

“You might not think that is not related, but they are. Disease problems, health problems, are compounded during times of disasters. These things need to be considered in the planning process,” said Lagmay.

 

 

ILOILO AT RISK

Dr. Francia Avila, a climatologist from the Manila Observatory based at the Ateneo De Manila University (ADMU), cleared the connections between climate change and flooding in Iloilo City.

Avila pointed out three things that affect flooding in the area: the high risk of flooding in the city, complacency due to projections of no significant changes leading to extreme events, and non-extreme climate events which may still lead to extreme impact.

She mentioned a Low Pressure Area which led to flooding in Iloilo province a week earlier as a result of a monthly accumulated rainfall up to 250 millimeters of rain.

This was already more than half of the total monthly rainfall in Iloilo City 15 years ago, which was only slightly higher than 100 mm.

She showed the climate projections for Iloilo City, which indicated significant increase in the average temperature.

There were no significant changes in average rainfall and extreme rainfall events, with a 5 percent decrease in annual rainfall, but an increase of 3 percent to the contribution to total annual rainfall.

She warned however, that the indication of “no significant change” meant that the current conditions will most likely continue in the future.

This included the typhoon “Frank”-like flooding and flashflood events like the recent ones in the province.

She said that the topography and the constrictions which were mentioned by Siringan and Lagmay should be considered when determining the presence of floods.

She also emphasized that placing cement all over the urban area will increase the runoff of sediment towards the rivers, gradually decreasing the depth of the riverbeds and contributing to a rise in the water levels.

“The climate impacts are not just the cause of flooding. There are the constrictions and the topography. I’d like also to highlight that putting cement all over the urban area will increase runoff, increase temperatures which will increase your risk for flooding,” Avila said.

Avila likewise pointed out that exposed and vulnerable communities are still at risk of extreme impacts from non-extreme weather and climate events.

The impact comes from three factors: Hazards which include climate extremes, geological hazards and astronomical tides; Exposure based on land use, high population density, and high economic value; and Vulnerability based on literacy levels, access to housing, access to water, and economic dependency.

She said that these factors will determine the number of casualties, of affected people, and of economic damage, among others.

 

AREAS AT RISK

Dr. Gay Defiesta from UPV Division of Social Sciences and Prof. Jessica Dator Bercilla from the UPV Institute of Fisheries Policy and Development Studies presented their study on flooding and social vulnerabilities in Iloilo City.

This study was done as part of the overall enhanced climate disaster and risk assessment (CDRA) for the city by the UPV, Manila Observatory and Iloilo City Planning Office under the Coastal Cities at Risk project of ADMU.

It is a social vulnerability analysis, resulting to a social vulnerability index for all the barangays of Iloilo City.

Social vulnerability analyses show the socio-economic and political contexts in which hazards occur thus providing a comprehensive understanding of the disaster risks confronting the city.

The analysis factored in storm surges, flooding, and the current COVID-19 pandemic.

Social vulnerability is described by Defiesta as a pre-existing condition, driven by socio-political, historical, and economic processes and structure which weaken a community’s ability to prevent human suffering and economic losses in disaster events.

A total of 18 indicators were used to determine social vulnerability, which included age, sex, population density, dependency, housing, informal settling, disability, education, and water access, to name a few.

Results of the index showed of 180 barangays, 67 percent or 121 barangays were at “Moderate” social vulnerability, 20 percent or 36 barangays were at a “Low” level, and the remaining 13 percent or 23 barangays were at “High”.

Defiesta said it reflected the socio-economic status of households in Iloilo City.

Using the index, they came up with a social vulnerability map, which they interposed with the city’s flood map to be able to show which barangays were at risk.

The study found that a total of 72 barangays were at risk, with 240,360 people, or 54 percent of the population, would be exposed based on the 2015 census.

Out of the people exposed, 51.13 of them are female and 2 percent are persons with disability (PWD).

Defiesta also presented the top five flood-prone barangays which are also at great risk when it comes to social vulnerability: San Isidro, Tabuc Suba, Dungon A, Calubihan, and Dungon B, all in Jaro district.

San Isidro and Tabuc Suba are two of the most populous barangays in the city.

The consolidated vulnerability present in these five barangays, from the results of the study, comprise of a 17,383 population density, with a 50.4 percent female population, 11 percent of children aged 5 and below, 6 percent of senior citizens aged 65 and above, and 1.7 percent PWDs.

Also included are 47 percent dependency ratio, which Defiesta said could hamper recovery, and 60 percent without access to Level III water supply, which could increase water-borne illnesses.

The Philippine Statistics Authority defines a Level III water supply as a facility with a source, a reservoir, a piped distribution network with adequate treatment facility and household taps.

There are 13 percent of houses or 565 houses in these barangays made of light materials, which are highly prone to damage.

 

CORRECT RESILIENCY

In the second part of their study presentation, Prof. Bercilla took the opportunity to correct the public misconception of the term “resilience”.

The term has been under fire online in the past years for allegedly being used to romanticize survival during disasters, with the anger rising this year over recent storm and flood events.

Bercilla pointed out that the hazards are inevitable, but the people can act against vulnerability through resiliency.

“There’s not much we can do about hazards because these are natural hazards, anthropogenic hazards and we do have to mitigate, for example, greenhouse gas emissions. There’s still something we can do about reducing our exposure, through land use planning, through zoning. But a great deal we can act on is reducing our vulnerabilities and enhancing our resilience,” said Bercilla.

She clarified that the acts being done by people to survive disasters are not “resilience” as others would put it, but only a part of it.

She also consolidated the definitions of resilience by various international bodies to come up with a brief description of resilience.

According to Bercilla, resilience is “the ability of social, economic, and environmental systems, community or society exposed to hazardous event or trend or disturbance to anticipate, resist, absorb, accommodate, cope, adapt to, transform, and recover from the effects of hazard in a timely and efficient manner, including through the preservation and restoration or improvement of its essential basic strctures and functions through risk management while also maintaining the capacity for adaptation, learning, and transformation.

“What we saw in the pictures that people hated the most, even our students hated the most, when they said, ‘Enough of the resilience!’ It’s not actually resilience. It’s grit. It is coping. But they are an essential part of the continuum known as resilience,” she said.

Bercilla and Defiesta’s study said the impact being faced by the areas at greater risk in the city includes:

– Livelihoods disruption due to flooding which will affect access to basic needs and services leading to food, health, livelihoods, and mental health insecurity (increased depression and suicide rates);

– Displacement and compromised health safety with prolonged exposure to flood waters;

– Water-borne diseases due to contamination which will increase the need for healthcare resources, increasing morbidity, mortality, and pressure in the health system; and

– Local transmission during evacuation before and during flooding due to COVID-19 and other health concerns.

The study recommended the following options to reduce exposure and vulnerability:

– Engage community in flood prevention initiatives (e.g. drainage, prevent chokepoints, reclaim waterways);

– Promote alternative and supplemental flood-resilient livelihoods;

– Enhancement of Iloilo City’s and Iloilo province’s Shelter Plan and Zoning informed by risk assessments (build vertical, landbank, and resettle); and

– Enhancement of alternative clean water access in times of flooding and increase the scope of clean water access via the Metro Iloilo Water District (MIWD)