A vulnerability assessment to flooding in flood prone areas a case study in selected three 3 barangays in santa rosa city laguna province in the philippines

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY JOHN MAVERICK SAYABOC DE LEON A VULNERABILITY ASSESSMENT TO FLOODING IN FLOOD PRONE AREAS: A CASE STUDY IN SELECTED THREE

THAI NGUYEN UNIVERSITY

UNIVERSITY OF AGRICULTURE AND FORESTRY

JOHN MAVERICK SAYABOC DE LEON

A VULNERABILITY ASSESSMENT TO FLOODING IN FLOOD PRONE AREAS: A CASE STUDY IN SELECTED THREE (3) BARANGAYS IN SANTA ROSA CITY, LAGUNA PROVINCE IN THE PHILIPPINES

BACHELOR THESIS

Study Mode: Full-time

Major : Environmental Science and Management

Faculty: International Programs Office

Thai Nguyen, 2017

DOCUMENTATION PAGE WITH ABSTRACT

Thai Nguyen University of Agriculture and Forestry

Degree Program Bachelor of Environmental Science and Management Student Name John Maverick S De Leon

Thesis Title A Vulnerability Assessment to flooding in flood prone

areas: A case study in selected three (3) Barangays in Santa Rosa City, Laguna province in the Philippines Supervisor(s) 1 Prof Dr Damasa Macandog (Philippines);

2 Assoc Prof Dr Tran Quoc Hung (Vietnam) Abstract:

The Philippines is one of the typhoon-prone countries in the world Twenty (20)

or more typhoons strike the country in a year This calamity results in flood or flashflood in the Philippines A vulnerability assessment is a must to the flood- prone areas in the Philippines to lessen the negative effects of flood to these areas as well as to the people living in them A community-vulnerability assessment was conducted in three lakeshore barangays of Sta Rosa City namely: barangay Aplaya, barangay Caingin and barangay Sinalhan This was done by conducting a survey to 50 residents in each of the three barangays and also to some city and barangay officials The main objective of the study is to conduct a community-based vulnerability assessment to floods of the three barangays in the City of Santa Rosa along the shoreline of Laguna de Bay This study generally aims to survey these communities with respect to their exposure, sensitivity, impacts and capability to adapt to floods The other objectives of the study are determining the reasons why the three barangays are vulnerable to flood, determine the experiences, observations, and coping mechanisms of the residents in the three barangays during floods and extreme weather conditions, find out views of the residents of the three barangays on government intervention and implementation of policies during floods and extreme weather conditions, assess the vulnerability of these communities to flooding using the data gathered and recommend appropriate adaptation strategies to residents and mitigation policies to government officials to lessen the effects of flooding to these areas based on the assessment The results of the survey were used for the Physical Vulnerability Analysis and Socio-Economic Vulnerability Analysis In conclusion, barangay Sinalhan is the most vulnerable among the three lakeshore barangays in the city of Santa Rosa based on the conducted Physical and Socio- Economic Vulnerability Analysis

Keywords: Vulnerability Assessment , Flooding

Numbers of Pages Ninety-Six (96) pages

Date of Submission November 2017

Signature of the

Supervisor

ACKNOWLEDGEMENT

I am most grateful to my thesis supervisor, Prof Dr Damasa Macandog, Professor, Institute of Biological Science, University of the Philippines at Los Banos (UPLB) in the Philippines for her help, guidance, encouragement, and patience throughout the implementation of this research study Her valuable suggestions and criticism on my thesis topic and on the manuscript are greatly appreciated Also, I am thankful to her for financing

my research study during the data gathering process in the research sites I would also like to thank my second thesis adviser in Vietnam, Assoc Prof Dr Tran Quoc Hung, Dean, Faculty

of Forestry, Thai Nguyen University of Agriculture and Forestry (TUAF) in Vietnam for his utmost support, valuable advice and guidance on my research study

I would like to acknowledge the assistance and support of several people during the course of my research study Engr Charles Gunay for his help and unending assistance during the process of data gathering in the three barangays in Santa Rosa City, Laguna Also, for his help in providing references for the research study Mr Donald Luna, Ms Elena Eugenio, and

Mr Job Jonas Ruzgal for their help, giving valuable suggestions, and for providing references

on my study Mr Ozzy Boy Nicopior and Ms Anne Jellie Bacani for their advice, guidance and help in mapping the necessary GPS coordinates on my thesis

I sincerely thank Ms Amor Salandanan, City Environmental and Natural Resources Office (CENRO) Official for her help and advice on my research study I would also like to thank Ms Linda Creencia and Mr Eldrin Ramos, CENRO officials for their help and assistance for asking permits in conducting survey in the three barangay research sites in Santa Rosa City I am also thankful to Mr Antonio Z Lu and Mr Mark Nino Villanueva from the City Disaster Risk Reduction Management Office (CDRRMO), Mr Gary Abadines from the City Planning and Management Office, Mr Joseph Milko U Bustamante from City Veterinarian Office, and Mr Gerwin U Adduru from the Local Building Office for giving time to participate in the Key informant survey I give special credit to Honorable Mayor Danilo Fernandez for agreeing and giving permission to gather necessary data in the three barangays in the City of Santa Rosa, Laguna Philippines

I sincerely thank all the Barangay Secretary Mr Benjamin Barairo from Barangay Caingin, Mr Felix P Claros from Barangay Aplaya and Ms Che Pacheco from Barangay Sinalhan for giving time to participate for the key informant survey and for granting my

request to conduct a household survey in each of the three barangays I am also thankful to the Barangay Officials who assisted and guided us while conducting the household survey I also give special credit to the three honorable Barangay Captains in the three research sites for allowing us to conduct household survey in their barangay and for assigning some barangay officials to guide us during the survey

I would like to extend my gratitude to Ms Susana Mutya, Ms Imelda Bautista, Ms Lenny Ann De Leon, Ms Roselyn Marcelo, Mr Jonas Dungan, Ms Rosette Dela Torre, Ms Jonalyn Suarez, Ms Roselle Cabugason, and Ms Ruby Thea Balao-as, for agreeing to be the survey enumerators and helped me in conducting the household survey I am also grateful to the 150 survey respondents from Barangay Caingin, Barangay Aplaya and Barangay Sinalhan for their hospitality and for allotting time to participate in the household survey

I am sincerely thankful to my grandmother, Perlina Howard for reading my manuscript and for helping and giving valuable suggestions on my study I also give special credit to Dr Zenaida Sumalde for teaching me to assign different codes to the gathered data and for giving valuable advices on my research study and Mr Nestor Parafina for helping and reading my manuscript I wish to thank and acknowledge the help of Dr Nerissa Torreta to find a supervisor for me

To my mother Lenny Ann De Leon, my grandmother Perlina Howard, my grandfather Bill Howard, my father Iric M De Leon, my two siblings Iris Anne De Leon and Phriya Nadine De Leon, my great grandmother Estrelita Dungan, my uncle Engr Antonio Sayaboc Jr., my relatives, my best friends Rosette Princess Dela Torre and Rhonalyn P Agupo and to

my friends, I deeply appreciate and cherish your love, prayers, understanding and unending support in the completion and success of my thesis

Above all, to God Almighty, thank you for giving me inspiration and determination to finish my research study Also, for giving the right solutions to my problems I encountered during my study

JMSDL

TABLE OF CONTENTS:

Title Page……….……… ………… i

Abstract……… ………….……… ii

Acknowledgement……… ……… iii

Table of Contents……….……….………… v

List of Figures……….……… ix

List of Tables……….…… ….…… xii

List of Abbreviations……… … …… xiii

CHAPTER I: INTRODUCTION……… 1

1.1 Research Rationale and Background……….… ………… 1

1.1.1 Background of the Study……… ….……… 1

1.1.2 Climate Change and its Effects……… 1

1.1.3 Cause and Effects of Flooding……… 2

1.1.4 Flooding in Santa Rosa City, Laguna Philippines……… 3

1.2 Significance of the study……… ………… ………… 4

1.3 Objectives of the study……….……… ……… 4

1.3.1 General Objectives……….……… 4

1.3.2 Specific Objectives……… ….….……… 5

1.4 Research Questions and Hypotheses……… …….……… 5

1.4.1 Research Questions……….……… 5

1.4.2 Hypotheses……….……… 6

1.5 Scope and Limitations……… ………… 6

1.6 Definition of Terms……… ….………… 6

CHAPTER II: LITERATURE REVIEW……… 7

2.1 Background about Flooding……… 7

2.2 Community-based Vulnerability Assessment to Flooding…….….…… 8

2.3 Factors Affecting the Vulnerability of Communities……… 12

2.3.1 Population Growth and Distribution……… 12

2.3.2 Social Diversity……… 13

2.3.3 Physical Characteristics……….……… 15

2.4 Related Studies in Vulnerability Assessment to Flooding……….…….… 16

CHAPTER III: METHODOLOGY……… …… 21

3.1 Materials, Instruments and Sources of GPS Data……….…… 21

3.1.1 Survey Questionnaires……….………… 21

3.1.2 Materials, Instruments and GPS Data for Creating the Necessary Maps……….……… 22

3.1.2.1 Geographical Location Using ArcGIS 10.2 Software……….……….………… 22

3.1.2.2 Location Map of Surveyed Areas Using ArcGIS 10.2 Software……….……… 22

3.1.2.3 Flood Susceptibility Map and Population Flood Exposure Map Using ArcGIS 10.2 Software………… 23

3.2 Time and Place of the Study……….……… 24

3.3 The Research Design……….……….……… 24

3.4 Conduction of the Survey……… ……… 25

3.4.1 Determination of the Area to Survey……….……… 25

3.4.2 Determination of Sample Size and Sampling……… …… 25

3.4.2.1 Household Survey……….………… 25

3.4.2.2 Key Informant Survey……… 26

3.4.3 Data Gathering Process……… ……… 27

3.4.3.1 Household Survey……… 27

3.4.3.2 Key Informant Survey……….……… 27

3.5 Organization and Analysis of Data……….………… 28

3.6 The Conceptual Framework of the study……… 29

CHAPTER IV: RESULTS AND DISCUSSION……… 31

4.1 Exposure to Flooding……… ……… ……… 31

4.1.1 Population Characteristics……… ……….……… 31

4.1.2 Location and Flood Susceptibility……….……… 32

4.2.1 Highest Level and Duration of Flooding……… 35

4.2.2 Problems Encountered During Flooding Incidents………… … 37

4.2.3 Damage to Buildings……… 39

4.2.4 Damage to Building Contents……… … 40

4.2.5 Impacts on Livelihood and Income……… … 41

4.2.6 Impacts on Human Life and Health……… ……… 43

4.3 Adaptive Capacity and Coping Mechanisms to Floods……….… 44

4.3.1 Warning Strategies of the City officials and Barangay Officials……… ……… 44

4.3.2 Forms of Local Government Assistance during and After Flood Events……….…… 45

4.3.3 Views of the Respondents on Local Government Intervention Before, During, and After Flood Events……… …… 51

4.3.4 Coping Mechanisms of the Surveyed Households……….… 52

4.4 Vulnerability Analysis……… 57

4.4.1 Physical Vulnerability Analysis……… ………… 57

4.4.1.1 Building Material Analysis……… 57

4.4.1.2 Effect of Height of Ground Floor and Distance from Lake……… ……… 64

4.4.1.3 Effect of Building Age and Number of Floors……… 67

4.4.2 Socio-Economic Vulnerability Analysis……… 69

4.4.2.1 Income……… … 69

4.4.2.2 Livelihood and Period of Stay……….… 70

4.4.2.3 Size of Family and Gender……….… 72

4.4.2.4 Age, Educational Attainment and Ownership……… 73

4.4.2.5 Calculation of Vulnerability Values/Scores………… 75

4.5 Recommendations to the Local Government Based on the Results……….……… 77

CHAPTER V: CONCLUSION AND RECOMMENDATIONS ….….… 79

5.1 Reasons for Flood Vulnerability……….………….………….… 79

5.2 Impacts of Floods……… 80

5.3 Adaptive Capacity and Coping Mechanisms……… … 80

5.4 Views on Government Intervention Before, During, and After Flood Events……….……… … 82

5.5 Vulnerability Assessment….……….… 82

5.6 Disaster Risk Reduction and Management Recommendations for Flood Hazards……….…… 83

5.7 Recommendations for future studies……… 83

LITERATURE CITED……….……….… 85

APPENDICES……….……….…… 97

LIST OF FIGURES:

Figure 1: The Geographical Location Map of the three barangay research sites

(Barangay Sinalhan, Aplaya, and Caingin) in the City of Santa Rosa in Laguna

Figure 4: The Population Flood Exposure Map of the Surveyed Areas in the

Three Barangay Research Sites……… ………… 23

Figure 5: City of Sta Rosa Flash Flood Areas and Submerged Barangays Map

(Source: City Planning and Development Office)… ………… 25

Figure 6: Left to Right Top Row The Survey Team Members in Action in

barangays (6a) Aplaya, (6b) Caingin, and (6c) Sinalhan Photos of the (6d)

CDRRMO and (6e) CPDO Left to Right Bottom Row Photos of (6f) City

Veterinarian Office and (6g) Local Building Office The researcher with the

officials of barangays (6h) Aplaya, (6i) Caingin, and (6j)

Sinalhan……… ………… 28

Figure 8: Location Map and Flood Susceptibility Map of the Three Barangay

Figure 9: Percentage of the Total Area of Flood Susceptibility Zones in (a)

Caingin, (b) Aplaya and (c) Sinalhan……… 34

Figure 10: (a) The Highest Flood Water-Level Experienced in Previous Years

(b) Flood Duration of the Highest Flood Water-Level Experienced in Previous

Figure 14: Impact of Floods on Livelihood of the Respondents: (a) General

Effects on Income and Livelihood; (b) Effect on Income (PhP) Due to Flooding;

(c) Effects on Ability to Work During and After

Figure 15: Awareness of the Respondents on an impending flooding event

Figure 16: Government Actions/Intervention Done by the Local Government

Units Felt/Experienced by the Respondents of the Three Barangay Sites

Figure 17: Views of the Respondents on Government Intervention Before,

Figure 18: Coping Mechanisms of Respondents With Respect to the Safety and

Figure 19: Coping Mechanisms of Respondents in Securing Their House

Figure 20: Availability of Insurances of the Surveyed Households in the

Figure 21: Kinds of Support that the Respondents in the Barangays Received

from Friends, Relatives and Neighbors During and After the Occurrence of

Figure 22: Extent of Damage of Each Structural Type in Barangay Caingin: (a)

Number of Structural Type and (b) Percentage of Structural

Figure 23: Extent of Damage of Each Structural Type in Barangay Aplaya: (a)

Number of Structural Type and (b) Percentage of Structural

Type……… 60

Figure 24: Extent of Damage of Each Structural Type in Barangay Sinalhan: (a)

Number of Structural Type and (b) Percentage of Structural

Type……… 62

Figure 25: Residents evacuate to the roofs during a flood hazard event………… 63

Figure 26: Effect of Ground Floor Height on the Extent of Damage (%) to

Houses in Barangays (a) Caingin; (b) Aplaya; and (c) Sinalhan from

Floods……… 65

Figure 27: Effect of Distance from the Lake on the Extent of Damage (%) to

Houses in Barangays (a) Caingin; (b) Aplaya; and (c) Sinalhan from

Floods……… 66

Figure 28: Effect of Building Age on the Extent of Damage (%) to Houses in

Barangays (a) Caingin; (b) Aplaya; and (c) Sinalhan from

Floods……… 67

Figure 29: Effect of Number of Floors on the Extent of Damage (%) to Houses

in Barangays (a) Caingin; (b) Aplaya; and (c) Sinalhan from

Figure 30: Income of all Earning Members of the Surveyed Households in

Barangays Caingin, Aplaya, and Sinalhan……… 69

Figure 31: The Different Jobs/Livelihood of all the members in the Surveyed

Households from Barangays Caingin, Aplaya and Sinalhan

Figure 32: Period of Stay of the Surveyed Households in Barangays Caingin,

Aplaya and Sinalhan……… 71

Figure 33: Household Size of the Surveyed Households in Barangays Caingin,

Figure 34: Gender of All Members of All Surveyed Households in Barangays

Figure 35: Age of All Members of All Surveyed Households in Barangays

Figure 36: Educational Attainment of All Members of All Surveyed Households

in Barangays Caingin, Aplaya, and Sinalhan ………… 74

Figure 37: Ownership of All Surveyed Households in Barangays Caingin,

Aplaya, and Sinalhan……… 74

LIST OF TABLES:

Table 2: Theoretical Indicators of Social Vulnerability……… 14

Table 3: Population, Population Density, Number of Households, Average

Number of Members per Household of the Three Surveyed Barangay of the City

Table 4: Warning strategies of the city and barangay officials before/during

Table 5: Assistance Given by the Barangays and Sta.Rosa City to the Affected

Table 8: Sources and Allocation of Emergency Funds in Case of Disasters in the

Table 9: Rescue Materials/Equipment and Rescue Vehicles used by the Three

Barangays and Sta Rosa City for Rescue Operation in Times of Emergent

Table 12: Current Flood Mitigation Measures of the Three Barangays and the

Table 13: Weighting Matrix of Socio-Economic Vulnerability……… 69

Table 14: Social Vulnerability Scores/Values for Various Socio-economic

Table 15: Value Ranges for the Classes of Socio-economic Vulnerability

Adopted from Zein (2010)……… 77

Table 16: Formulated disaster reduction and management recommendations… 78

CALABARZON “Cavite, Laguna, Batangas, Rizal and Quezon”

CDRRMO City Disaster Risk Reduction and Management Office

LDRRMP Local Disaster Risk Reduction and Management Plan

LGU Local Government Unit

UNFCCC United Nations Framework Convention on Climate Change

CHAPTER I:

INTRODUCTION

1.1 Research Rationale and Background

1.1.1 Background of the Study

A community-based vulnerability assessment to flooding of three barangays located along the lakeshore of Santa Rosa City namely: Sinalhan, Aplaya and Caingin were done The data produced in the study will be used for developing appropriate policies that can be implemented by the City of Sta Rosa during flooding in these areas

1.1.2 Climate Change and its Effects

The United Nations Framework Convention on Climate Change (UNFCCC) defines climate change as a change of climate that is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and that is in addition to natural climate variability Global climate changes the main reason why climate is displaced and some hazards such as floods, earthquakes, hurricanes and typhoons occur more or fewer in some areas in the Earth (National Research Council, 2010) Evidence of climate change can be seen in the Philippines through the changing patterns of the Southwest monsoon (SW) The intensity of the SW passing through the Philippines is stronger than normal which brings in longer rainy season and more typhoons that result to more flooding making it one of the flood prone countries in the world

1.1.3 Causes and Effects of Flooding

When high intensity rains or more typhoons strike an area which has no proper drainage systems or when canals, dams, and other waterways are clogged with garbage, the large volumes of run-off water will cause flooding Extreme weather conditions also create an excess of runoff that is above the capacity of the drainage systems in an area (Adetunji and Oyeleye, 2013)

Flooding is an extremely dangerous natural event and it has the potential to wipe away an entire city and the coastline areas which causes extensive damage to life and property (eSchooltoday, 2010) The socio-economic status or well-being of a community is primarily affected by flooding (bbc.co, 2017) Not only will it cause deaths and injuries to people, it can also cause damage to property, destruction of crops, loss of livestock, and deterioration of health conditions As communication links and infrastructure such as power plants, roads and bridges are damaged, people are forced to leave their homes and normal life is disrupted (chiefscientist, 2017) Similarly, loss of livelihood, damage to infrastructure, reduction in purchasing power and loss of land value can leave communities economically vulnerable and can cause long-term impacts (Hamburg University of Technology, 2010) Floods can also be a traumatic experience and can cause deep impacts for the victims and their families especially on children Displacement from one's home, loss of property and disruption

to business and social affairs can cause continuing stress For some people the psychological impacts can be long lasting (chiefscientist, 2017)

1.1.4 Flooding in Santa Rosa City, Laguna Philippines

In Laguna Province in Region IV-A (CALABARZON) in the Philippines, Santa Rosa City is one of the areas which experiences severe flooding when long rainy seasons and rampant typhoons strike It has a total area of 54.84 km2 (21.17 square miles) covering its 18 barangays with an average elevation of 20.3 meters (National Statistical Coordination Board, 2013) It has a total population of 353,767 having a population density of 6,500 per square kilometer (Census of Population, 2015) Santa Rosa City lies at 14°17ˈ 03ˈ ˈ N and 121°05ˈ 20ˈ ˈ E (earthexplorer.com) Santa Rosa City‟s Flash Flood Areas and Submerged Barangays Map, indicates that barangays Sinalhan, Aplaya and Caingin are among the most affected communities during flooding in the city

The communities in Santa Rosa City located along the shores of the vast Laguna de Bay are proven to be prone or more vulnerable to flooding when long rainy seasons and prevalent typhoons strike In recent years, super typhoons such as Milenyo (2006), Ondoy (2009), and Glenda (2014) greatly affected low-lying or coastal communities of Santa Rosa city The research sites of the study are communities located along the lake shores of Santa Rosa city namely: Barangay Sinalhan, Barangay Aplaya, and Barangay Caingin which are mostly residential areas due to large population of residents The total number of households and residents in the three barangay research sites are: 3,449 households with 15,519 residents in Barangay Aplaya, 4,799 households with 21,597 residents in Barangay Caingin, and 4,844 households with 21,797 residents in Barangay Sinalhan (City Environment and Natural Resources Office, 2015) Barangay Aplaya lies at 14°19ˈ 11ˈ ˈ N and

121°07ˈ 12ˈ ˈ E, Barangay

121°07ˈ 37ˈ ˈ E, and Barangay Sinalhan lies at

121°06ˈ 31ˈ ˈ E (earthexplorer.com) The geographical location of the three research sites is shown

in Figure 1

1.2 Significance of the Study

This study aims to assess the vulnerability to floods of three communities in the City of Santa Rosa along the shoreline of Laguna de Bay This will be done by conducting a community-based survey on the exposure, sensitivity, impacts and capacity to adapt to floods of these communities This study will help develop and recommend specific adaptation and mitigation strategies in these three barangays to lessen the impacts of flooding The earlier this assessment is done, the faster the authorities could proactively institute risk management and damage control

1.3 Objective of the Study

1.3.1 General Objective

The main objective of the study is to survey these communities with respect to their exposure, sensitivity, impacts and capability to adapt to floods

Figure 1 The Geographical Location Map of the three

barangay research sites (Barangay Sinalhan, Aplaya, and

Caingin) in the City of Santa Rosa in Laguna Philippines

1.3.2 Specific Objectives

There are five (5) specific objectives in the study The study was specifically done to:

1 Determine the reasons why the three barangays are vulnerable to flood;

2 Determine the experiences, observations, and coping mechanisms of the residents in the three barangays during floods and extreme weather conditions;

3 Find out views of the residents of the three barangays on government intervention and implementation of policies during floods and extreme weather conditions;

4 Assess the vulnerability of these communities to flooding using the data gathered; and

5 Recommend appropriate adaptation and mitigation strategies to residents and local government officials of Santa Rosa City

1.4 Research Questions and Hypotheses

1.4.1 Research Questions

There are five (5) questions that the research study will answer, these are:

1 Which barangay of Sta Rosa city are more or less vulnerable to flooding?

2 Why are these communities vulnerable or less vulnerable to flooding?

3 What do the people in these areas experienced during extreme weather events?

4 How do the residents view the government policies and actions during flooding?

5 What are the mitigation and adaptation strategies that will help the communities?

1.5 Scope and Limitations

The study covers the fact finding to generate a database which will serve as flood mitigation reference Survey on the views of residents as to exposure, sensitivity, impact and adaptive capability of their communities to floods are included The assessment and recommendations made are however limited only to the views of the residents and the government actions and mitigation measures/practices based on the key informant survey with city and barangay officials Technical recommendation on how to resolve the flooding problems is not included herein It shall be the role of another group or institution to come up with doable plans addressing the issue discussed in this work

1.6 Definition of Terms

The definition of terms is presented in Appendix E

CHAPTER II:

LITERATURE REVIEW

2.1 Background about Flooding

Flooding is defined as too much water in a new area or it is when water has overflown in to a place that is normally dry (Alberta Water Portal, 2013) Flooding can cause damages to some property or buildings and infrastructures, injuries and deaths to humans, increase the risk of water-borne diseases such as typhoid fever, cholera, leptospirosis and hepatitis A and diseases from vectors such as mosquitoes causing dengue fever and malaria (medicardphilippines and who.int) This environmental hazard occurs in and affects different countries in the world In fact Nasiri et al (2016) stated the many urban areas worldwide are likely to experience the serious effects of floods They further indicated that regular flooding will occur because of global climate change, rapid urbanization and land conversion causing in the decline recharge

of groundwater by extension of impermeable surface, and poor watershed

management

Improper drainage systems or polluted canals, dams and waterways are some of the reasons why flooding is intensified in an area Stuck and clogged garbage causes a large inflow of water not to be drained properly causing floods Moreover, urbanization and industrialization are also reasons why flooding occurs in an area As the population increases rapidly, some of the agricultural areas or open areas will be converted into residential or built-up areas and infrastructure transforming its permeable soil to an impermeable surface (Konrad, 2016) In addition, prolonged high intensity rainfall or rainfall from typhoons and monsoon rains causing overflowing of

water from lakes, rivers and other bodies of water can also result to flooding of an area Prolonged high intensity rainfall will transform the soil to become saturated until the soil will no longer be able to absorb or store large volume of water leading to increased surface runoff Further, the excess water will enter the rivers, lakes or other

bodies of water until it overflows leading to higher levels of flood (Jackson, 2017)

2.2 Community-based Vulnerability Assessment to Flooding

Managing flood hazards with the aim of safety and well-being of the people and saving their environment are few of the main responsibilities of the authorities or local governments in the flood prone areas by reducing vulnerability levels and increasing resilience of the people in flood-stricken locales (Nasiri et al., 2016) One of the procedures and the first in this process is assessing the vulnerability level of the area and its people to identify vulnerability issues to ultimately adopt effective and appropriate adaptive and coping measures (Takemoto, 2011)

Basically, vulnerability assessment is an assessment to assess the exposure, sensitivity, impacts, adaptive and coping capacities of an area and its people to natural calamities such as typhoons, landslides, earthquakes, and floods Vulnerability assessment or vulnerability analysis is a risk management process to quantify, identify, and rank possible vulnerabilities to threats in an area (Techopedia, 2017) Such studies identify and determine the spatial location of people during disasters and the extent of the effects of these natural threats to the people (Okayo et al 2015 and Mendel, 2006)

It is a location-specific study because the vulnerability level of an area differs with the type of hazard and the physical and geological characteristics of an area and socio-economic features of its people

With numerous studies on assessing vulnerability, it has no universal definition (Birkmann, 2007) and since it is interdisciplinary, the definition of vulnerability varies with context (Füssel, 2010) That is why the concept of vulnerability is approached from different professional fields and disciplines by disaster management agencies, the academe, and the climate change community (De Leon, 2006) According to Intergovernmental Panel on Climate Change (IPCC), vulnerability is the degree of susceptibility and the inability to manage climate variability and extremes by a system (IPCC, 2014) It refers to the state of receptiveness to the harmful effects from exposure to different climate hazards and the ability to cope with and recover from such calamities (UNDP, 2014) Table 1 shows the list of the other important definitions of vulnerability from different sources as cited by Nasiri et al in 2016

Table 1 Other Definitions of Vulnerability

Alexander (2002)

It is the vulnerability of people and things to losses attribute to a certain amount of danger and probability that it is visible in a special condition and with a certain degree

UNDP (2004)

It is the condition which is influenced by physical, social, economic and environmental factors that increased the susceptibility of people to the impact of hazards

Wisner (2004)

It is the characteristics of an individual or group of people and their condition that affect their ability to predict, struggle, tackling, and recover from the effects of the environmental threats or natural disasters

Adger (2006) It is the susceptibility to harm from exposure to pressures related with

environmental and social changes, and in lack of adaptation ability

Næss (2006) It is a function of exposure, sensitivity, and adaptive capacity generated by

multiple factors and processes

Borden et al (2007)

Distinct Vulnerability means potential or sensitivity to losses or harm Social vulnerability contains the susceptibility of the society or social groups to potential losses from hazards

Balica and Wright

(2010)

It is defined as interaction between exposure, susceptibility, and resilience of each community in risk condition

Source: Nasiri et al (2016)

Vulnerability to natural hazards can be classified into four (Kingma and van Westen, 2009 as cited by Fernandez et al., 2016) These are physical, social,

economic, and environmental vulnerabilities Physical vulnerability includes factors that control flood effects on the physical infrastructure of people in a certain area In his physical vulnerability analysis of Kelurawan Sehu in Indonesia, Zein in 2010, considered building structure, height of ground floor, number of floors, building age, and building contents as factors affecting the physical vulnerability of an area Guarin

et al (2004) in their flood risk assessment of the town of San Sebastian in Guatemala considered building, building contents, and road networks as physical factors affecting vulnerability In addition to this, a study on the physical vulnerability of residents in Jabonga, Agusan del Sur in the Philippines, near lake Mainit, also considered distance from the lake as one of the factors affecting physical vulnerability (Crisologo et al., 2016) Socio-economic vulnerability tackles effect of floods on economic assets, source of livelihood and amount of income, and event groups (Kingma and van Westen, 2009) It also includes coping mechanisms and adaptive capacities of people based on age and gender distribution, livelihood and income, educational level, period

of stay, housing status, and household size (Zein, 2010) The combination of these two types of vulnerability is a function of hazards and their physical impacts, exposure of the elements affected by these hazards, and sensitivity or lack of capacity of a population to prepare, absorb, and recover from natural calamities (Gotangco and Perez, 2017) Physical and socio-economic vulnerability are the only concerns in this study

In order to reduce the impacts residents in an area experience before, during, and after a natural hazard such as floods, a community-based vulnerability is a must These impacts are commonly measured in terms of costs to businesses, property, and

infrastructure Compared to damages to buildings, however, the total effects of flood hazards are much greater especially to people who have fewer access to resources and less capacity for recovery Due to various socio-economic and physical factors, there are residents within an area that are more vulnerable to the effects of flood hazards than the others It is essential to do the community-based vulnerability assessment as early as possible for the community to formulate mitigation and adaptation strategies for flood hazards which can happen anytime With mitigation and adaptation strategies

in place, the vulnerability to flooding of people in an area will decrease and their resilience to flood hazards will increase To strengthen and raise awareness of disaster-prone areas, community participation in disaster mitigation policy-making and implementation is important so as the community‟s involvement in flood assessment through their experiences to reduce impacts to flood hazards (Zein, 2010) Furthermore, in developing countries such as the Philippines, community-based approaches are more cost-effective and not technology demanding when gathering, consolidating, and recreating experiences of victims in flood-prone regions (Guarin et al., 2004)

In this study, a community-based vulnerability assessment to flooding was performed Primary data was gathered through a community-based survey Secondary data was also gathered from the city government and barangay officials of barangays Caingin, Aplaya, and Sinalhan

2.3 Factors Affecting the Vulnerability of Communities

2.3.1 Population Growth and Distribution

The vulnerability to specific hazards or disasters increases with increasing population densities and rapid and high degree of urbanization (Perrow, 2007) Large population density residing in urban coastal and flood-prone areas causing congestion and dense infrastructures coupled with poverty may intensify the vulnerability of a community to disasters causing high rates of injuries and fatalities (Donner and Rodriguez, 2008)

In their historical literature review of human impacts on flooding events from

1980 – 2009, Doocey et al in 2013, in their five literature reviews, stated that rapid population growth and land conversion have increased human vulnerability to flood hazards and its impacts either directly or indirectly They also found out that because

of rapid population growth near coastlines, increased coastal areas and floodplain developments, degradation to the environment, and climate change, there will be considerable risks posed by future floods Furthermore, as confirmed by other historical reviews, they stated that flood-related deaths although varying with geographical region, level of economic development, and severity of event, are more concentrated in developing and heavily populated countries because countries with more resources are better equipped to prepare and respond to future flood events

Population growth increases both the likelihood and the potential impact of flooding by increasing the pressure on sewer systems and prompting urban expansion into areas at high risk of flooding Rising sea levels and changing rainfall patterns are expected to make floods more frequent and intense over the coming decades The

global poor are especially exposed to flooding and vulnerable to its damage Slowing population growth by encouraging smaller families and meeting unmet demand for family planning materials should be pursued in parallel with flood and climate change adaptation

2.3.2 Social Diversity

The socio-economic characteristics of a population may limit their ability to protect themselves from harm brought about by impacts of a natural hazard (Donner and Rodriguez, 2011) For example, people in an area that have higher average incomes and lower poverty levels are less vulnerable than people experiencing the contrary Poverty is one of the primary factors affecting how people perceive and understand risks and how well they respond to the warnings (Fothergill and Peek, 2004) Widespread poverty in a population has played a major role in increasing the vulnerability of communities to disasters or hazards such as floods (Wisner and Walker, 2007)

Age, disability, presence of diseases, gender, livelihood, income, educational attainment, and housing status are other socio-economic factors that affect the vulnerability of a community to flood hazards Communities with a larger percentage

of children, elderly, females, and uneducated or undereducated individuals, higher number of disabled individuals and individuals having existing diseases, lower income and scarce sources of livelihood, and high percentage of residents renting rather than owning their own homes are more vulnerable to flood hazards than those communities having the contrary (Zein, 2010)

An even more detailed presentation of theoretical socio-economic indicators was given by Rufat et al in 2015 (Table 2) based on social vulnerability literature He emphasized the need to quantify social vulnerability to identify vulnerable areas and which aspects of social vulnerability are significant

Table 2 Theoretical Indicators of Social Vulnerability

Thematic indicators Specific indicators

Coping capacity

Individual capacity Household capacity Social capital

Demographic characteristics

Age Race and ethnicity Family structure Gender Functional needs Language proficiency

Health

Access Stress Disease Mortality Sanitation Land tenure

Owners Renters Squatters

Neighborhood characteristics

Transportation Population density Housing Resource dependency

Risk perception

Awareness Prior experience Knowledge of flood protection measures

Risk denial/acceptance Trust in officials

Socioeconomic status

Income Wealth Education Occupation

Source: Rufat et al (2015)

2.3.3 Physical Characteristics

The formulation of mitigation strategies and its subsequent implementation relies on a thorough vulnerability analysis of the physical factors at risk Ultimately, the data from these assessments can be used in planning mechanisms to evaluate damages and minimize economic losses (Mazzarona et al., 2014)

A physical vulnerability assessment of two areas in Sanit Lucia by Uwakwe in

2015 used building description and contents, building occupancy and function, building materials, number of floors, building maintenance, building style, and building age, size, elevation, and ownership In the study, physical vulnerability was assessed using the depth-damage method to assess vulnerability of building structures and the Spatial Multi-Criteria Evaluation (SMCE) to assess the vulnerability of all buildings in the two areas From the first method, results show that the most vulnerable building structure from the eight identified structural types is the building built with wood floors, wood walls, and GI sheet roofs On the other hand, results from SMCE indicate that in the areas of study, Castries old CBD and Dennery Village, the percentage of building that are highly susceptible to floods is 14% and 36%, respectively In another study in two Eastern England coastal towns by Kelman (2002) identified failures in building structures using number of building storeys, relative height of buildings, elevation, height of walls, floor and exterior perimeter area, building design, building age, and types and number of walls, doors, windows, and other openings to two-dimensional vulnerability matrices These matrices were then used to create possible disaster management systems

2.4 Related Studies in Vulnerability Assessment to Flooding

Although vulnerability assessment on flooding is a relatively new research field, a number of researches have already been done Strauss et al (2015) reported that in some $7.8 billion in property in Louisiana in the United States owned by more than 236,398 people living in more than 101,621 homes in the coastal areas are not protected by levees making them vulnerable to floods They found out further that high concentration of populations and a wide range of properties, infrastructure and buildings in low-lying areas are affected the most In the places where population is high, the most socially vulnerable populations are most affected They concluded however that knowledge of these vulnerabilities can lead to better preparation before a flood is to occur Furthermore, they stated that although higher probabilities of future floods in these areas are certain, but the extent of damages they inflict will depend on the measures coastal communities take

In 2015, Eguaroje et al used Geographical Information System (GIS) and remote sensing techniques to make a flood vulnerability maps in 11 areas of Ibadan, Nigeria Their analysis revealed that the main contributor to flooding is the mean annual rainfall followed by slope, drainage, and land use Another study using GIS is that of Karmakar et al in 2010 which used physical, economic, infrastructure, and social components to flood to determine overall vulnerability by evaluation each component individually and then in combination using GIS Implemented in six main damage centers in the Upper Thames River watershed in the South-Western Canada, the flood system derived from the study will be used by the general public, decision-

makers, and water management professionals to formulate policies and mitigation mechanisms relating to floods

A community-based approach to flood hazard and vulnerability assessment in Kelurahan Sewu in Surakarta City in Indonesia was done by Zein in 2010 In his study, he interviewed one hundred four (104) respondents to assess their physical and socio-economic vulnerabilities to floods In his assessment of the vulnerability of building structures, he found out that from the four most common types of structural buildings, the most vulnerable to floods are built with concrete floors, mixed-material walls, and clay roofs Overall, however, from the nine types of structural buildings, the most vulnerable are buildings made of ground (soil) floors and bamboo walls He found out further that the vulnerability of building contents is related to flood depth and the socio-economic status of the residents For socio-economic vulnerability of the same area, he concluded that based on a combination of different socio-economic factors, most of the households have moderate to low vulnerability to floods With this result, he concluded further that because the socio-economic vulnerability of residents

in the study area is low, they still choose to live in these flood-prone areas

Studies using both GIS data and the community-based approach were conducted by Fernandez et al, (2016) in Portugal, Guarin et al (2004) in Guatemala, Muller et al (2011) in Chile, and Rodriguez et al (2011) in Colombia In their social vulnerability analysis in the inter and intra civil parish and municipal levels, Fernandez and his team found out that, that in the most pessimistic scenario, high and very high levels of social vulnerability to floods were observed in 57% - 68% of the study area The flood vulnerability assessment results of Guarin and his team were used to generate

vulnerability maps to estimate losses in flood hazards His team further created a database based on physical and social information combined with detailed flood hazard, vulnerability, and estimated losses data which the municipality of San Sebastian in Guatemala can use in planning for flood disasters Muller‟s team investigated the vulnerability of city of Santiago and surrounding municipalities in Chile to flood risks In this study, data from GIS, census, remote sensing data, and household surveys were used to derive vulnerability maps for two municipalities located in the eastern part of the city of Santiago Lastly, Rodriguez‟s team used a multiscale, multi-temporal, and multidisciplinary approach to assess the vulnerability

to flooding in areas located between Bolivar, Sucre, and Magdalena in Colombia Information on maximum events such as flood depth and duration and benchmarks of the stations for grid accuracy combined with the satellite image data were used to create new flood polygons which were ultimately associated with flood return periods Final mapping of threats using the gathered data were generated using the method specified by Barriendos and Coeur (2004) which was eventually used to identify appropriate risk management mechanisms by developing of GIS-based scenarios for different types of risk and vulnerability reduction to floods

Kablan et al (2017) conducted a survey to randomly selected 584 households to describe the current state of environmental parameters that contribute to flooding and its impact to the residents in urban Ivory Coast in West Africa The gathered data were used to create flood maps with respect to exposure, susceptibility, and resilience using ArcGIS software The results revealed that many sub-districts of Cocody in the Ivory

Coast are highly-vulnerable to urban floods due to high risk of exposure and susceptibility of the residents in the district of Cocody

The study of Antwi et al (2015) used rural participatory research approaches in developing four vulnerability categories namely ecological, socio-economic, engineering and political These were used to develop indicators that aided in the calculation of the total community vulnerability index for each community in the Wa West District of Ghana The results indicate that a community's degree of vulnerability

to flood is a combined effect of the four vulnerability index categories, independently

or concurrently to produce the net effect Based on the total vulnerability scores of each community, Baleufili was the least vulnerable to flood due to its high engineering, socio-economic and political indicators levels However, Baleufili together with Bankpama were the most ecologically vulnerable communities

In the Philippines, a vulnerability assessment to landslides and flooding along the Santa Rosa-Silang Riverine System using LiDAR and GIS-based hydrological modeling technologies was conducted by Magcale-Macandog et al in 2015 Their results indicate that communities located in coastal areas and along the riverbanks in the downstream areas of the Sta Rosa-Silang Riverine System are more vulnerable to floods than communities far from the bodies of water This observation is reflected in the generated flood hazard maps by local government units within the Santa Rosa-Silang Riverine System

Other vulnerability assessment studies in the Philippines are those conducted by Pati (2011) in the towns of Mabitac and Sta Maria in Laguna and Dagoc (2012) in Cagayan de Oro City A vulnerability analysis from the data gathered by Pati through

a survey in the towns of Mabitac and Santa Maria was developed The data from the survey was used to created necessary maps for the vulnerability analysis The social vulnerability analysis performed in the research sites indicated that barangays Jose Rizal, Masinao, Adia, and Coralan in Santa Maria and barangays San Antonio, Nanguma, Lambac, and Pagasa in Mabitac are very vulnerable to floods In Cagayan

de Oro, Dagoc adopted a GIS-aided flood risk assessment in three low-lying barangays

of Iponan River Watershed Basic socio-economics and household structure information were gathered from 145 respondents This together with household coordinates determined using GPS were used to create different vulnerability maps

These studies have greatly contributed in the increased understanding of the impacts of flood hazards and its mitigation These investigative works also stresses the value and importance of conducting vulnerability assessments to floods in an area or community The results of which will help people in the Philippines and all over the world prepare for, adapt to, cope with, and mitigate the impacts of flood hazards

This study focused on developing a vulnerability analysis in three barangays identified as flood-prone areas in the City of Santa Rosa City in Laguna in the Philippines Because of the lack of community-based vulnerability assessments in the flood-prone areas in the City of Santa Rosa that focuses on the experiences of people,

it is imperative that a community-based physical and socio-economic vulnerability assessment to flooding should be done to formulate mitigation, coping, and adaptation strategies by both the residents and the local government to lessen the fatalities, decrease physical destruction to properties, and other effects of flooding in the flood-prone areas of the city

CHAPTER III:

METHODOLOGY

3.1 Materials, Instruments, and Sources of GPS Data

The materials and instruments used for the research study are survey questionnaires, ArcGIS 10.2 software, Household (GPS) coordinates and shapefile of administrative boundaries and flood susceptibility data of the Philippines from the databases of the PhilGIS.org and the Mines and Geosciences Bureau Survey questionnaires were used for gathering pertinent data from the respondents in the research sites The ArcGIS 10.2 software was used to locate the geographical location

of the three research sites and to locate the surveyed areas in the three research sites together with the GPS coordinates of the areas of the households surveyed The software was also used to create the flood susceptibility map and population flood exposure map of the three barangay research sites

3.1.1 Survey Questionnaires

A questionnaire that was used in the study for the household survey was prepared (Appendix A) The survey contained questions about the personal information and the demographic and socio-economic profile of the respondents and the members of their households, their experiences on floods, their perception of the impacts of flooding on their respective families and properties, their coping mechanisms in times of flood, and their assessment on government intervention during floods and the efficiency and effectiveness of the adaptive mechanisms set-up by the local government The questionnaire is divided into seven parts: (1) General Information; (2) Demographic Profile; (3) Building/Property Information and

Structure; (4) Livelihood Activities; (5) Experiences with Flood; (6) Disaster Recovery and Adaptation/Coping Strategies; and (7) Health and Social Networks

Another questionnaire was prepared and used for the key informant survey or the survey performed on barangay and city officials related flood (Appendix B) The questionnaire was divided into two parts: (1) respondent‟s personal information and (2) information on government intervention or adaptive mechanisms set-up by the local government with respect to floods

3.1.2 Materials, Instruments, and GPS Data for Creating the Necessary Maps

3.1.2.1 Geographical Location Using ArcGIS 10.2 Software

The ArcGIS 10.2 software together with the dataset of the administrative boundaries of the Philippines together with the provincial, municipal, and barangay boundaries (ESRI shapefile) gathered from PhilGIS.org were used in creating the map

of the geographical location of the three barangay research sites The location Map of the three barangay research sites is shown in Figure 1

3.1.2.2 Location Map of Surveyed

Areas Using ArcGIS 10.2 Software

The ArcGIS 10.2 software

together with the dataset of the

administrative boundaries of the

Philippines together with the

provincial, municipal, and barangay

boundaries (ESRI shapefile) gathered

Figure 2 Location Map of the Surveyed Areas in the

three barangay research sites

from PhilGIS.org and the obtained household (GPS) coordinates during the community-based survey were used in creating the location map of the surveyed areas

in barangays Caingin, Aplaya, and Sinalhan The location map of the surveyed areas in the research sites is shown in Figure 2

3.1.2.3 Flood Susceptibility Map and Population Flood Exposure Map Using

ArcGIS 10.2 Software

The ArcGIS 10.2 software together with the 10k Flood Map (Flood Susceptibility Data of the Philippines) from the Mines and Geosciences Bureau and the dataset of the administrative boundaries of Philippines together with the provincial, municipal, and barangay boundaries (ESRI shapefile) gathered from PhilGIS.org were used for creating the flood susceptibility map of the three barangay research sites in the City of Santa Rosa in Laguna province The data stated above together with the GPS coordinates gathered from the survey was also used to create the population flood exposure map The Figure 3 shows the Flood Susceptibility Map of the three barangay

research sites and the Population Flood Exposure Map is shown in Figure 4

Figure 3 Flood Susceptibility Map of the

Three Barangay Research Sites

Figure 4 The Population Flood Exposure

Map of the Surveyed Areas in the Three Barangay Research Sites

3.2 Time and Place of the Study

This study was done in four months from March 2017 to June 2017 at the Institute of Biological Science in Eco-informatics Laboratory of University of the Philippines Los Banos, Laguna Philippines The household survey was conducted in three communities that are identified flood-prone based on the Flash Flood Areas and Submerged Barangays Map of the City of Sta Rosa in Laguna province in the Philippines The key informant survey was conducted on the City Hall of Santa Rosa and on the Barangay Hall of the research sites

3.3 The Research Design

An assessment of the vulnerability to floods of three barangays in the City of Sta Rosa, Caingin, Aplaya, and Sinalhan, was conducted This study used an observational and participatory (community-based) approach to gather data Survey is the method used to gather pertinent data to answer the research questions because it is the most appropriate sampling method based on the adopted investigative approach The data were gathered by conducting a household survey using the prepared questionnaire in 50 households from six zones (purok in the vernacular) in each of the three barangays The data gathered in the survey were collated and organized in tables The organized data were then analyzed using simple descriptive statistical tools, ANOVA and presented using graphs and were discussed The GPS coordinates of the surveyed areas in the selected research sites were also obtained for the mapping of the location of the different surveyed areas in each barangay Data were also obtained by conducting a key informant survey using another set of prepared questionnaire using four city officials as respondents from different departments based on their expertise

and one barangay official from each of the three barangay research sites The data from the key informant survey were then organized in tables and explained in

narrative

3.4 Conduction of the Survey

3.4.1 Determination of the Areas to Survey

The City of Sta Rosa‟s Flash Flood

Areas and Submerged Barangays Map from

the CPDO of Santa Rosa City (Figure 5)

was used to determine the three

flood-prone barangays where the survey will be

conducted As shown in the map, barangay

Caingin, barangay Aplaya and barangay

Sinalhan were chosen not only because

they are part of the submerged areas in City

of Sta Rosa during the onslaught of the

southwest monsoon (habagat) but also

because the barangays in consideration are the only barangays in the City of Sta Rosa bounded by the Laguna Lake Thus, the residents of the three barangays were sampled for the survey

3.4.2 Determination of Sample Size and Sampling

3.4.2.1 Household Survey

At first, a simplified formula for proportions suggested by Yamane (1967) was used to determine the appropriate sample size for the household survey of this study

Figure 5 City of Sta Rosa Flash Flood

Areas and Submerged Barangays Map (Source: City Planning and Development Office)

This formula yielded the appropriate sample size of about 369 respondents for barangays Caingin and Sinalhan and 358 respondents in barangay Aplaya However, due to the limited time and resources in conducting the research, the purposive sampling method was used instead Using the method, the sample size for the whole study was set at 150 households, 50 for each barangay The researcher chooses the respondents or households randomly with no criteria in each three barangays since purposive sampling method was used With the help of the accompanying barangay officials from each of the three barangays during the survey, they are the one who recommend the people or households that were mostly affected by floods in the barangays that can be part of the survey The households/respondents were also surveyed depending on their availability and willingness to be surveyed In each of the barangays, 50 households were chosen from the six zones (purok) In barangays Caingin and Aplaya, eight households from Purok 1 to 4 and nine households from Purok 5 and 6 were randomly chosen For barangay Sinalhan, nine households in Purok 1 and 6 and eight households from Purok 2 to 5 were randomly selected

3.4.2.2 Key Informant Survey

Four city officials based on their expertise were chosen to participate in the Key Informant Survey The city officials that participated in the study are: (1) one city official from City Planning and Development Office (CPDO); (2) one city official from Local Building Office (Engineering Office); (3) one city official from City Veterinarian Office; and (4) one city official from City Disaster Risk Reduction Management Office (CDRRMO) Also, one barangay official from each of the three barangay research sites was interviewed in the key informant survey