Flood control expert Dr. Guillermo Tabios III on Typhoon Carina | The Howie Severino Podcast

Summary

The discussion centers on the aftermath of Typhoon Karina, highlighting the impact of climate change, poor waste management, and reclamation projects in Manila Bay. It emphasizes the need for a holistic approach to flood risk management, starting from the headwaters to the downstream areas. The conversation underscores the significance of controlling sedimentation from deforestation and the challenges posed by heavy rains in the Philippines. It also points out the lack of a dedicated body for flood risk management and the importance of adaptive planning and simulation models to address different flood scenarios.

Takeaways

• 🌀 Typhoon Karina has had a significant impact on many people, highlighting the need for better flood risk management.
• 🌍 Climate change, litter, and reclamation projects in Manila Bay are mentioned as contributing factors to the flooding issues.
• 🏞️ Deforestation and lack of reforestation are identified as problems that exacerbate the sedimentation in rivers, reducing their capacity to handle water.
• 🌲 The importance of controlling sediment from upstream sources, such as forests, is emphasized to maintain river depth and flow.
• 🚧 The script discusses the role of infrastructure like bridges in contributing to sedimentation and the subsequent reduction in river capacity.
• 🌧️ The challenges of managing heavy rains, especially in a humid tropical climate with potential rainfall of 400-500mm in a day, are highlighted.
• 🌊 The script mentions the need for a holistic approach to flood risk management, starting from the headwaters and moving downstream.
• 🛣️ The issue of debris from mountains and riverbanks contributing to river roughness and friction is discussed.
• 🏙️ The lack of a dedicated body in the Philippines for daily or regular flood risk management and planning is pointed out.
• 🔍 The necessity for running simulation models to understand the impact of different flood control measures in various sub-basins of Metro Manila is emphasized.

Q & A

What is the main topic of discussion in the transcript?

The main topic of discussion is the impact of Typhoon Karina and various factors contributing to natural disasters in the Philippines, including climate change, reclamation projects, waste management, master planning, deforestation, and flood risk management.

What does the speaker attribute as the primary cause mentioned by the president after Typhoon Karina?

The president attributed the disaster primarily to climate change.

What is the role of reclamation projects in Manila Bay according to the transcript?

Reclamation projects in Manila Bay are mentioned as a significant factor contributing to environmental issues and are criticized by some people, including senators.

What is the importance of a holistic approach to flood risk management as mentioned in the transcript?

A holistic approach to flood risk management involves considering the entire watershed, from the headwaters to the downstream areas, to effectively manage and control flood risks.

Why are sediments in rivers a concern in the context of flood control?

Sediments in rivers reduce the capacity of the rivers to hold water, which can exacerbate flooding issues, especially during heavy rainfall events.

What is the role of forests in minimizing sediment runoff from watersheds?

Forests help to minimize sediment runoff by holding the soil in place, reducing the amount of sediment that enters rivers and streams during rainfall.

What is an example of a structural measure mentioned in the transcript to control sedimentation?

An example given is the construction of an overflow bridge in Loyola Grand Villa that helps manage water flow and sedimentation during floods.

What is the impact of sedimentation on the depth of rivers, as described in the transcript?

Sedimentation can fill up the riverbed, reducing the depth of the river and its capacity to carry water, which can lead to more severe flooding.

What is the significance of debris from the mountains in the context of flood risk management?

Debris from the mountains, such as logs or vegetation, can create friction and roughness in the river, affecting water flow and potentially contributing to flooding.

Why is it challenging to control the impact of heavy rainfall events like those experienced during Typhoon Karina?

Heavy rainfall events can produce an overwhelming amount of water in a short period, making it difficult to manage and control the resulting floods, especially in areas with poor infrastructure and planning.

What is the speaker's observation regarding the lack of a dedicated body for flood risk management in the Philippines?

The speaker notes the absence of a dedicated body that focuses on flood risk management or planning on an ongoing basis, which could help in better preparing for and mitigating the effects of floods.

How does the speaker suggest running simulations for flood risk management?

The speaker suggests running simulation models for different scenarios, including structural and non-structural measures, to understand their potential impact and effectiveness in various areas.

What is the difference between the flood parameters used in the 2010 master plan and the actual rainfall experienced during Typhoon Karina?

The 2010 master plan's flood parameters were based on a two-day rainfall event, whereas Typhoon Karina produced heavy rainfall over a longer period, demonstrating the need for updated flood risk assessments.

Outlines

00:00

🌪️ Typhoon Karina's Impact and Flood Management

This paragraph discusses the aftermath of Typhoon Karina and the various factors contributing to flooding in the region. It mentions the president's reference to climate change and waste as significant issues, while senators point to the reclamation project in Manila Bay as a major factor. The paragraph emphasizes the importance of a holistic approach to flood risk management, starting from the headwaters and moving downstream. It highlights the role of sediment control, the impact of deforestation, and the need for effective flood planning and management. The discussion also touches on the challenges of managing sediment from watersheds and the effects of debris on river capacity, suggesting the need for a dedicated body to address flood risk management.

05:00

🌧️ Flood Simulation and Planning for Metro Manila

The second paragraph delves into the complexities of flood simulation and planning, particularly in Metro Manila's sub-basins like Marikina and Tulyahan. It stresses the need for academic research and the running of simulation models to predict the outcomes of different structural and non-structural measures. The discussion points out the differences in flood-generating mechanisms between typhoons and habagat, and how the current master plan, designed with parameters based on a 2-day rainfall, may not be sufficient for the region's unique weather patterns. The paragraph also contrasts the rainfall patterns of Typhoons Ondoy and Ulysis with those of Typhoons Habagat and Karina, highlighting the challenges in managing floods that can last for extended periods with varying intensities.

Keywords

💡Typhoon Karina

Typhoon Karina refers to a specific tropical storm that caused significant damage and was mentioned as a recent experience in the video script. It is central to the discussion as it exemplifies the type of natural disasters that the video addresses. The script discusses how factors like climate change, waste management, and reclamation projects in Manila Bay might have contributed to the severity of the typhoon's impact.

💡Climate Change

Climate change is a key concept in the video, as it is identified as a contributing factor to the intensity and frequency of natural disasters like typhoons. The video suggests that climate change exacerbates weather events, which in turn affects the vulnerability of communities to such disasters. The script mentions how the president himself cited climate change as a factor in the wake of the disaster.

💡Reclamation Projects

Reclamation projects in Manila Bay are discussed as a potential factor in the flooding and disaster management. These projects involve land reclamation from bodies of water and are highlighted as a concern because they may alter natural water flow and drainage, contributing to flooding issues. The script suggests that a holistic approach to flood risk management should consider such projects.

💡Deforestation and Reforestation

Deforestation and reforestation are mentioned in the context of their impact on watersheds and flood control. Deforestation can lead to increased sedimentation in rivers, reducing their capacity to handle heavy rainfall, while reforestation can help mitigate this by stabilizing soil and reducing sediment runoff. The video implies that proper land management, including reforestation efforts, is crucial for flood risk management.

💡Sediment

Sediment is a significant concept in the video, as it relates to the capacity of rivers to handle water during heavy rainfall. The script describes how sedimentation from deforestation and other land use changes can reduce the depth and flow of rivers, which in turn lessens their ability to manage floodwaters. The example of the Tone Bridge in Loyola Grand Villa illustrates how sediment buildup can obstruct water flow.

💡Upland Watersheds

Upland watersheds are mentioned as the starting point for managing flood risks. These are areas where water originates and flows through rivers and streams. The video emphasizes the importance of a holistic approach that begins with managing these watersheds to control sediment and debris that can clog rivers downstream. The script suggests that measures to minimize sediment runoff from these areas are essential for flood risk management.

💡Flood Risk Management

Flood risk management is a central theme in the video, focusing on strategies to mitigate the impact of floods. The script discusses various factors that contribute to flood risks, such as sedimentation, deforestation, and land reclamation, and how they can be managed. It also highlights the need for a comprehensive approach that considers all aspects of flood control, from upstream watersheds to downstream flood plains.

💡Holistic Approach

A holistic approach is emphasized in the video as the best method for addressing flood risk management. This approach involves considering all relevant factors and stakeholders in developing strategies to manage flood risks. The script suggests that a piecemeal or fragmented approach is insufficient, and that a coordinated, comprehensive strategy is necessary to effectively manage flood risks.

💡Master Planning

Master planning is mentioned in the context of urban and environmental management. The video discusses the lack of a master plan for flood control and suggests that having a well-thought-out, comprehensive plan is crucial for effective disaster management. The script critiques the current approach, which is described as lacking a unified strategy and consisting of small, disconnected projects.

💡Habagat

Habagat refers to the southwest monsoon in the Philippines, which brings heavy rains and can lead to flooding. The video contrasts the habagat with typhoons, highlighting the different challenges they present for flood management. The script uses the habagat as an example of a weather pattern that requires specific planning and management strategies to mitigate flood risks.

💡Simulation Models

Simulation models are discussed as tools for predicting and managing flood risks. The video suggests that these models can help planners understand how different management strategies might affect flood outcomes under various scenarios. The script implies that the use of simulation models is a critical component of a holistic approach to flood risk management, allowing for the testing of different strategies before implementation.

Highlights

Typhoon Karina's impact on many people highlighted the importance of addressing climate change, waste management, and reclamation projects.

The need for a holistic approach to flood risk management was emphasized, starting from the headwaters and upland watersheds.

Sediment control is crucial for maintaining river capacity, and forests play a key role in minimizing sediment runoff.

The example of the overflow bridge in Loyola Grand Villa illustrates how sediment accumulation can reduce river depth and capacity.

Deforestation and lack of reforestation contribute to increased sedimentation in rivers.

The Philippines lacks a dedicated body for daily flood risk management or adaptive planning for flood control.

Academic research and simulation models are necessary to understand the impact of structural and non-structural measures on flood control.

Different sub-basins in Metro Manila require tailored flood management strategies.

The 2010 World Bank master plan for flood parameters was based on 2-day rainfall, which may not account for the intensity and duration of recent storms.

The habagat of August 2012 and Typhoon Karina demonstrated the challenges of managing multiple days of continuous rainfall.

The archipelagic nature of the Philippines presents unique challenges for flood management and sediment control.

Quarrying along river banks contributes to sedimentation and river capacity reduction.

Debris from mountains, such as logs and vegetation, creates roughness and friction in rivers, affecting flow.

The intensity of tropical rains, like those experienced during Typhoon Karina, is difficult to control and poses significant flood risks.

The need for a dedicated body to manage flood risks on an ongoing basis is emphasized, rather than sporadic studies.

The complexity of flood generation mechanisms, such as typhoons and habagat, requires a nuanced approach to flood management.

Transcripts

so doc No I just want to ask you

specifically about Typhoon karina kasi

Iyan ang recent experience ng maraming

tao at ah in the wake of that disaster

ang daming mga factors nga yung

nabanggit no ung pangulo mismo no

nabanggit niya climate change ang basura

ung ibang tao naman ah pati mga senador

no sinasabi ah malaking factor itong

reclamation project sa Manila Bay ah Ang

daming nagtuturuan pasaway kasi mga tao

nabanggit niyo rin yung yung basura and

then nabanggit niyo rin yung Uh Master

planning sabi ng iba eh Wala ngang

Master plan puro mga maliliit na

projects and of course there's the issue

of deforestation at kulang sa

reforestation how do this fit together

no ano yyung pinakamalaking ah factor

kasi given na yung low lying tayo no

given na yan hindi naman pwedeng i-

evacuate yung Metro Manila nyan na yan

So what's the best way of Uh adapting no

should we for example stop the

reclamation

projects reclamation was different story

but when you look at the flood control

definitely You have to start from the

headwaters sa upland watersheds all the

way down now that's what we always say

holistic approach to flood risk

management now

one of the things

that really reduces the capacity of the

rivers yung sediments So how do you

control

sed upstream ba meron ng mga control

maybe you have forest that will minimize

sediment Yel from the watersheds and

then gets into your River it Then

shallows the river imagine tyon that

area in Loyola grand Villa there was a

tone bridge doon and if you're aware of

that that crosses yung from Loyola grand

Villa gen Balara you go down there and

then you go across to San Mateo or or

Marikina non tuman that was an overflow

bridge So nakakadaan doon on top meron

kang concrete patos merong calbert sa

bottom and then pag mataas ang tubig

tatapon nandoon yung soh o hindi pwedeng

dumanon but during

on it it must have been filled up mga 2

to 3 meters of sediment over a period of

mga 7

hours so imaginin mo that area Syempre

na siya 2 to 3 me but think along the

river 2 to 3 met nawala iung depth na

ion So it will reduce that so much

capacity So that's one So that's why you

have to have controls excuse meuse

nanggaling yung sediment na nagbara ng

ilog Dahil ba na walang puno sa gubat ah

that's one because if you really a lot

of brain mahirap i-control Iyung

sediment na mager Ode from your

watersheds archipelagic countries ganoon

talaga ang problema whether you have

quarrying along the river banks and so

on but the the bulk of the sediment com

comes from the Iyung overland flow

Planes na watersheds mo

I mean not in the river but on the sides

you know So because you just have so

much

rain We are talking about humid tropic

rains which are like 400 500 mm in in

one day That's a lot of brain if you

think about it Anyway So you go down to

the downstream so na ng sediment

and nawala na yung capacity River mo Now

you also of some debris coming from the

mountains maybe mga logs or maybe some

of these Uh naed na mga vegetation they

will also contribute

to we call it a creates roughness of

friction B because you have this mga

roughness elements and so on so those

are things now if you think about those

kinds of rains na na-experience natin

onoy karina uis yung habagat or yung

Sudden onset ng mga TY na

storms it's just so much rain that we

are

experiencing so it's not quite easy to

control that as far so

yeah that's the problem you can do this

but one of the things that I've noticed

Philippines and That's where we don't

really have a dedicated body to Look at

this Uh flood risk management or flood

planning or adaptive planning for flood

control on a daily basis or when I say

daily is like Maybe you do a study

everyday but good for the next 3 months

or six months because a year ago ito na

ng nangyari and if you look at

Uh Metro Manila you have different sub

basins or where you have Marikina

tulyahan

nandoon sa sapte bacor and those areas

You have to as academic B You have to

run simulation models different

scenarios you change the LS What will

happen if you do this kind of a a

structural measure or non-structural

measures What happens Will it work Maybe

it works here But doesn't work another

place and then you think in terms of a a

flood na na Generating mechanism

typhoons are so much different from

habaga

in fact if you look at the master plan

na ginawa 2010 ah World Bank yung nagf

all the Uh design flood parameters we

call it based on a 2day rainfall based

on a one is to 50 one is 100 like one

shot over the next two days but we can

have

multiple picks in our flats our rain and

then it can even last for 5 days like

the habagat of 20

August that was 7 days ulan ng ulan

Mahina yung intensity pero over 7 days

you have more than what you got from

undoy or ulysis same thing with karina

you got in 3 days time you got more than

what

was what fell during onoy over almost 24

hours

455 24 hours kina about 600 over

3 days almost 65 hour