Flood Hazard Map Presentation
Results of Flood Hazard Mapping ofSurigao del NortePRESENTED BY:
Engr. SOCRATES F. PAAT, JR.
Hydrologist
Flood Forecasting Branch
PAGASA
PhilippinesOUTLINE OF PRESENTATION
I.
II.
III.
IV.

Introduction
General Techniques in Mapping Used
AnalysisPresentation of Outputs

I. Introduction
What is Flood? Is relatively high flow in a river or stream
What is Flooding ? Is overflowing of water from thenormal confines of a river or stream

What causes Floods.?

Heavy Rainfall
due to :Tropical Cyclones
Thunderstorms
Monsoons
Intertropical
Convergence Zone(ITCZ)
Cold Fronts

What is a River Basin? Is a drainage area of a river,stream or lake

RG2
RG1
WL1

WL2

RG3

Drainage BasinAnao-aon
RiverBasin

SurigaoRiverbasin
MayagRiverbasin

LambigueRiverBasin
MagpayangRiver Basin
CampoRiverBasin
DaywanRiverBasinRiver Basins in Mainland Surigao del NorteII. General Techniquesin Mapping Used
 Geomorphological Approach• Qualitative to semi quantitative• Employs study of landforms and associatedhazards• Uses Geomorphological Mapping System (TMU)• Necessity for remote sensing data and aerial
photographs• Necessity of fieldworks• Discipline-oriented

Methodology
Data Collection• Maps• Aerial photographs and remote sensing data
• Historical records of events• Previous works

Photo interpretation• Stereophoto interpretation• Drainage analysis• Delineation and identification ofGeomorphological Mapping SystemFieldworks•Verification and mappingTabletop Analysis (stereophoto-interpretation)• Photo-Interpretation using aerial photographs
or other remotely sensed data
• Topographic analysis using topographic or
relief maps
• Delineation of Geomorphological Mapping
System orTerrain mapping units (TMU)• Drainage basin inventory and quantification
Result = Preliminary Flood Hazard Map

Fieldworks (mapping and verification)•Detailed mapping of landform features•Mapping of critical river systems andsettlements•Actual interview of residents•Cross-checking of preliminary flood hazard
map•Correlation with available historical records
and actual interviews
Result= Final Flood Hazard Map

Data Collection

•

Maps

• Aerial
photographs

Data Collection• Satellite
Imageries

Data Collection
Source: Mines
andGeosciences
BureauFlood Hazard Map of the townof Mainit, Surigao del Norte• Previous works
Source: MPDO,Municipalityof Mainit

Flood Hazard Map of the townof Mainit, Surigao del NorteData Collection
Area =
3.98 sq.
kmArea =Anao-aon
38.46
sq. River Basin
km Area =38.46 sq.
km

• Drainage Analysis
Area =8.50
sq. kmArea = 67.83
sq. kmArea =
12.03 sq.
Area=3.91 sq. km
km
Area =8.04
sq. kmField Works• Location
Name of Sitio, Barangay
Municipality, Coordinates• Flood
Information
History, Frequency
Height, Depth, Extent, etc.

• Geomorphology• Resource Person

Survey Notes for San Francisco

Survey Notes for Mainit

Plotted Coordinates Using GPS - San FranciscoPlotted Coordinates Using GPS - MainitIII. Analysis

Preliminary Flood Hazard Map of San Francisco

Preliminary Flood Hazard Map of Mainit

IV. Presentation of Output

Training of Community Volunteer Observers•More than 200 volunteer
observers trained in 4 formal
trainings conducted in the 2provinces(Rainfall – water level – tidegauges / Disaster OperationCenter)

DRY RUN / Operationalization of the System•Dry Runs conducted in 3 key
areas in the 2 Provinces

DRY RUN / Operationalization of the System