Rainfall‐Runoff‐Inundation (RRI) Model
1D Diffusion
in River

Input
Subsurface + Surface
Vertical Infiltration

RainfallMain difference between typical distributed
R‐R models and RRI
OutputDischarge

DEM
W. Level

Distributed R‐R Model

RRI Model

Flow directions are fixedbased on topography

Flow directions change
based on water levels

Surface/subsurface flow conditions(A) Only overland flow
(no infiltration loss, nosubsurface flow)

Land CoverInundation
Cross Sec.

Three Conditions of Surface/Subsurface Flows(B) Vertical infiltration+ Infiltration excess
overland flow(C) Saturated subsurface+ Saturation excess
overland flow

2D Diffusion
on Land• This two‐dimensional model is capable of simulating rainfall‐runoff and flood inundation
simultaneously.
• The model deals with slopes and river channels separately.
• At a grid cell in which a river channel is located, the model assumes that both slope andriver are positioned within the same grid cell.
Sayama, T. et al.: Rainfall‐Runoff‐Inundation Analysis of Pakistan Flood 2010 at the Kabul River Basin,
Hydrological Sciences Journal, 57(2), pp. 298‐312, 2012.

1D Kinematic (or similar)Key Steps in RRI Modeling
Topography
Digital Elevation Model

Case study in Pampanga River Basin, Philippines

RainfallRainfall data

Outline of the basin

MyanmarFlow Accumulation:
Define the total numberof the upstream cells
draining into adownstream cell.

RRI Control File
RRI_Input.txt

Philippines

RRI ExecuteRiver water depth, river discharge,
slope water depth
Hydrograph
Flood hydrographCalculated discharge

Maximum flood inundation Depth

Observed discharge

2500
1020002015001000

30Rainfall (mm/hour)

03000

Indonesia
Forth largest river basin inthe Philippines

Inundation
Peak inundation depth

RRI Model Simulation for 2011 September Flood
Discharge (m3/s)

JapanChina

Flow Direction:
Identify the river path.

Rainfall (ground)

LandRiver
2D Diffusive

Pampanga
River BasinCatchment Area: 10,434 km2
River Length: 260 km
Average Annual Rainfall: 2155mm/year
Population: 5.8 million
Population Density: 460 persons/km2

Calumpit Municipality
Number of Barangays (Communities): 29

San Isidro

500
026-Sep

4027-Sep

28-Sep29-Sep30-Sep

1-Oct

2-Oct

3-Oct

4-Oct

Date

Comparison of calculated and observed
discharge at San Isidro Station
Interferometric Synthetic Aperture Radar(IfSAR) Data, provided by National
Mapping and Resource Information
Authority (NAMRIA), Philippines, areused in the calculation.

Based on statistical analysis using rainfall
data at 17 telemetric stations, the return
period is approximately 28.3 years.

Calumpit Municipality
Timeline Scenario (Inundation Chart)

Colors of Safety Markers•••

About 193 water-level markers (electric poles) areinstalled in Calumpit.
Each electric pole is color-coded with yellow, orange,
and red every 2 ft to provide a guide for evacuation.
Each marker has a designated contact person toreport water levels to MDRRMO (Municipal Disaster
Risk Reduction and Management Office).

6ft
4ft
The flood inundation depths calculated by RRI model at the locations of the colors of safety markers are presented in the table at 12‐hr intervals daily. The colors used topaint the cells in the table correspond to the ones on the safety markers.

2ft

Ordinary Flood: floods that occur quite frequently but the damage will not be very serious.
High Flood: floods that occur less frequently than ordinary floods (i.e., equivalent to the Typhoon Pedring flood) but the damage is likely to be greater.
Extreme Flood: floods that rarely occur but the damage will be very serious.

Discussion at Barangay

Discussion with MDRRMO

Discussion with local residents (January, 2016)

Explanation to municipal mayor (January, 2016)

International Centre for
Water Hazard and Risk Management
under the auspices of UNESCO

Final Workshop at
Municipality
on Feb. 17, 2016

Certificate of Appreciation

Discussion on revision of the Barangay DRR
and Management Plan (February, 2016)

Public Works Research Institute,
National Research and Development
Agency, Japan

International Centre for Water Hazard and Risk Management
under the auspices of UNESCO (ICHARM), Public Works Research Institute (PWRI)
RRI software is downloadable free of charge from the following website:
http://www.icharm.pwri.go.jp/research/rri/rri_top.html