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OPEN SOURCE WEB-BASED SOLUTIONS FOR DISSEMINATING AND ANALYZING FLOOD HAZARD INFORMATION AT THE COMMUNITY LEVEL

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Abstract

We discuss in this paper the development, including the features and functionalities, of an open source web-based flood hazard information dissemination and analytical system called “Flood EViDEns”. Flood EViDEns is short for “Flood Event Visualization and Damage Estimations”, an application that was developed by the Caraga State University to address the needs of local disaster managers in the Caraga Region in Mindanao, Philippines in accessing timely and relevant flood hazard information before, during and after the occurrence of flood disasters at the community (i.e., barangay and household) level. The web application made use of various free/open source web mapping and visualization technologies (GeoServer, GeoDjango, OpenLayers, Bootstrap), various geospatial datasets including LiDAR-derived elevation and information products, hydro-meteorological data, and flood simulation models to visualize various scenarios of flooding and its associated damages to infrastructures. The Flood EViDEns application facilitates the release and utilization of this flood-related information through a user-friendly front end interface consisting of web map and tables. A public version of the application can be accessed at http://121.97.192.11:8082/. The application is currently expanded to cover additional sites in Mindanao, Philippines through the “Geo-informatics for the Systematic Assessment of Flood Effects and Risks for a Resilient Mindanao” or the “Geo-SAFER Mindanao” Program.
OPEN SOURCE WEB-BASED SOLUTIONS FOR DISSEMINATING AND ANALYZING
FLOOD HAZARD INFORMATION AT THE COMMUNITY LEVEL
Meriam Makinano-Makinano-Santillan, Jojene R. Santillan*, Edsel Matt O. Morales
Caraga Center for Geo-informatics, Caraga State University, Butuan City, 8600, Philippines
- (mmsantillan, jrsantillan)@carsu.edu.ph
Commission IV, WG IV/9
KEY WORDS: Web-based Solutions, Flood hazards, Information Dissemination, Community-level Hazard Assessment, Flood
EViDEns
ABSTRACT:
We discuss in this paper the development, including the features and functionalities, of an open source web-based flood hazard
information dissemination and analytical system called “Flood EViDEns”. Flood EViDEns is short for “Flood Event Visualization
and Damage Estimations, an application that was developed by the Caraga State University to address the needs of local disaster
managers in the Caraga Region in Mindanao, Philippines in accessing timely and relevant flood hazard information before, during
and after the occurrence of flood disasters at the community (i.e., barangay and household) level. The web application made use of
various free/open source web mapping and visualization technologies (GeoServer, GeoDjango, OpenLayers, Bootstrap), various
geospatial datasets including LiDAR-derived elevation and information products, hydro-meteorological data, and flood simulation
models to visualize various scenarios of flooding and its associated damages to infrastructures. The Flood EViDEns application
facilitates the release and utilization of this flood-related information through a user-friendly front end interface consisting of web
map and tables. A public version of the application can be accessed at http://121.97.192.11:8082/. The application is currently
expanded to cover additional sites in Mindanao, Philippines through the “Geo-informatics for the Systematic Assessment of Flood
Effects and Risks for a Resilient Mindanao” or the “Geo-SAFER Mindanao” Program.
* Corresponding author
1. INTRODUCTION
Flood EViDEns, short for “Flood Event Visualization and
Damage Estimations”, is an application that was developed by
the Caraga State University Phil-LiDAR 1 Project to address
the needs of local disaster managers in the Caraga Region in
Mindanao, Philippines in accessing timely and relevant flood
hazard information before, during and after the occurrence of
flood disasters. The idea behind Flood EViDEns is all about
geospatially-informed decision making before, during and after
the occurrence of flood disasters. To formulate these decisions,
local disaster managers must have access to localized flood
hazard information that depicts not only the different scenarios
of flooding hazards but also other equally important layers like
the hazard levels and spatial extent of flooding, the elements
that are exposed, and the impacts that a particular scenario of
flood event will brought to the community.
The ‘community’ being referred here refers to the “barangay”
which is the smallest unit of governance in the Philippines.
Essentially, through Flood EVIDENs, barangay disaster
managers would be able to visualize and determine how many
houses would be flooded should a particular flood event will
occur in the future.
A similar application for web-based flood hazard impact
assessment in the Philippines is the ‘Project NOAH’ or the
“Project Nationwide Operational Assessment of Hazards”
(http://noah.dost.gov.ph). Project NOAH is capable of
portraying scenario-based flood hazard maps, including
determining the number of structures and populations that can
be affected should a particular flood scenario will occur.
However, the visualization and impact assessment that can be
made by Project NOAH is limited to the city/municipal level.
The development of Flood EViDENs and its deployment for
operational use by the LGUs becomes a necessity because most
of the Local Government Units (LGUs) in the Caraga Region do
not have the capability to generate these flood hazard
information, and even the hardware and software to conduct
visualization and analysis should these layers of information are
provided to them.
The conceptual basis and overviews of the initial version of
Flood EViDENs is reported in Santillan et al. (2015). However,
much of what has been reported in that paper refers to the ‘near-
real time’ or ‘dynamic’ version of Flood EViDEns.
The objective of the current paper is to report in detail the
‘static’ version of the web application, particularly on its
development and deployment, as well as its features and
functionalities. The main difference between the near-real
time and the static’ versions is that the former displays
dynamically generated flood hazard information in near-real
time, while the latter displays pre-generated, scenario-based
flood hazard information.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
This contribution has been peer-reviewed.
https://doi.org/10.5194/isprs-archives-XLII-2-W7-91-2017 | © Authors 2017. CC BY 4.0 License.
91
2. AREAS OF APPLICATIONS
The Flood EViDEns web application covers barangays in 41
cities/municipalities within the twelve (12) highly flood prone
river basins of Caraga Regions, Mindanao, Philippines (Figure
1). These river basins are actually the project areas of the CSU
Phil-LiDAR 1 Project.
Figure 1. The twelve river basins in Caraga Region, Mindanao,
Philippines covered by the Flood EViDEns application.
3. DEVELOPING THE WEB APPLICATION
3.1 Generating the Scenario-based, Static Flood Hazard
Information for Web-based Visualization and Analysis
Flood hazard information corresponding to various historical
and hypothetical scenarios (i.e., flooding due occurrence of
rainfall events of different return periods of 2, 5, 25, 50 and 100
years) were generated for each of the 12 river basins through the
use of flood simulation software/programs, particularly the
Hydrologic Engineering Center Hydrologic Modelling System
(HEC HMS) version 3.5 and HEC River Analysis System (HEC
RAS) version 5 (Makinano-Santillan and Santillan, 2015).
Various geospatial datasets were utilized in the development of
flood simulation models (Figure 2). In HEC HMSmodel
development, a 10-m Synthetic Aperture Radar (SAR) Digital
Elevation Model (DEM) was used for sub-basin delineations
and for derivation of topography-related parameters of the
model such as slope and elevation. Images acquired by the
Landsat 8 satellite were also utilized to derive a landcover map
using Maximum Likelihood classification. The landcover map
is necessary for the derivation of land-cover-related model
parameters such as surface roughness coefficient, and
runoff/infiltration capacities. River width and cross-section data
obtained from field surveys as well as those extracted from 1-m
resolution LiDAR-derived Digital Terrain Model (DTM) were
also used to estimate the channel routing parameters of the
model. For HEC RAS model development, river bed
topography (obtained from bathymetric surveys), sea bed
topography, LiDAR DTM, building footprints (with top
elevation) extracted from LiDAR Digital Surface Model (DSM),
and the same landcover map derived from Landsat 8 OLI
satellite image were used as major inputs.
For each historical flooding event and for each rainfall return
period, the HEC HMS-based hydrologic model computes for
the volume of water coming from the upstream watersheds.
Rainfall Intensity Duration Frequency (RIDF) curves generated
by the Philippine Atmospheric Geosphysical and Astronomical
Services (PAGASA) are used as input into the HEC HMS to
determine the volume of rainfall that is necessary to compute
discharge hydrographs for specific locations in the river basin,
specifically at those locations where the upstream watersheds
ends and the floodplain portions begin. The discharge
hydrographs depict the volume of water per unit time (in m3/s)
that drains into the main river at these locations. These
hydrographs are then used as basis to generate water level
forecasts, and as inputs into the HEC RAS two-dimensional (2D)
hydraulic model to generate the flood depth and hazard maps
for each rain return period. HEC RAS utilizes river and flood
plain geometric data (from topographic and hydrographic
surveys and LiDAR Digital Terrain Model - DTM), land-cover
and surface roughness (from remotely-sensed images), and
Figure 2. Some of the geospatial datasets used in the
development of the flood models. (from Santillan et
al., 2015)
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
This contribution has been peer-reviewed.
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92
discharge hydrographs in order to generate flood depth maps.
which, in turn are further processed to generate flood hazard
levels by categorizing flood depths into low (depth <0.5 m),
medium (0.5 ≤ depth ≤ 1.5 m), and high (depth > 1.5 m)
hazards. The flood hazard maps produced from this process are
in GIS shapefile format (one file each for the current flood
hazard map, and forecasted flood hazard map).
For each river basin, there were two historical and five
hypothetical flood hazard shapefiles computed. The historical
events include that of the Tropical Storms ‘Seniang’ and
‘Agaton’ flooding in 2014. The hypothetical scenarios
correspond to floods caused by rainfall events with return
periods of 2, 5, 25, 50 and 100 years.
The flood hazard shapefiles are then used as inputs to the back-
end of Flood EViDENs.
3.2 Generating the Flood Hazard Exposure Datasets for
Impact Assessment
In addition to flood hazard information, Flood EVIDEns also
requires the location and descriptions of structures that can be
exposed for flooding.
Buildings within the river basins were located and digitized
from the LiDAR DSMs using ArcGIS ArcMap. Buildings that
can be identified like schools, hospitals and other identifiable
built-ups are also included by means of manually inputting its
building name and code in the attribute table and validated
using field surveys and use of online web maps. Residential
buildings were identified and validated by interview and ocular
survey done by the partner LGUs. The information gathered
from the survey was also used in attribution of digitized
residential building. Detailed information of household like the
number of household members, their birthdate, educational
attainment, relation to the family head and their occupation
were also recorded into a “.csv” file and joined into the GIS
shapefile’s attribute table. An image of the building was also
taken during the survey and linked to each building in the
shapefile. The building shapefiles and photographs were then
used as inputs into the back-end of Flood EViDEns.
3.3 Developing the Back-end and Front-end of Flood
EViDEns
The back-end of Flood EViDEns was developed using the
following:
Django (GeoDjango module) is a high-level Python
Web framework that encourages rapid development
and clean, pragmatic design.
GeoServer an open source server for sharing
geospatial data
PostgreSQL (PostGIS plugin) - a powerful, open
source object-relational database system.
The application was mainly written in Python using Django
framework. Models (transformed as table in the database) were
created first and generated using “ogrinspect” command from
Django shell. The ogrinspect management command will
inspect the given OGR-compatible DataSource (e.g., the flood
shapefile) and will output a GeoDjango model with the given
model name. After the creation of model, “syncdb” command
was used to create tables on the PostgreSQL database and by
using the “Layer Mapping” utility of Django, shapefile is
transformed as Multipolygon and loaded in the database.
Once data models were created, Django automatically gives a
database-abstraction API (Application Program Interface) that
lets you create, retrieve, update and delete objects. All the
textual statistics like the estimated number of affected structures
(according to flood hazard level) and the detailed number of
affected structures (with its building name, building type, etc.)
were generated by executing a query (intersects or
ST_Intersects in PostGIS) using Django Object-relational
mapping (ORM). On the other hand, map visualization is
handled using GeoServer. Its data is from the PostgreSQL
database also. Web Map Service (WMS) is used for flood
hazard maps and Web Feature Service (WFS) for the affected
structures. This is because WMS allows GeoServer to use
GeoWebCache which makes the visualization faster and WFS
which outputs a vector layer when rendered, is used to zoom-in
to the location of the structure. Each flood hazard maps were
configured individually and styled using Styled Layer
Descriptor (SLD). SLD is an XML-based markup language for
Geospatial data styling in GeoServer.
For its front-end, the following were used:
JavaScript Libraries (Openlayers API, Highcharts,
JQuery, Google Maps)
Bootstrap - a popular HTML, CSS, and JS framework
for developing responsive, mobile first projects on the
web.
The entire user-interface (UI) of the application is configured
using Bootstrap framework with its predefined styles
(Cascading Style Sheet) and JavaScript functions. The
interaction between the user and the application is handled by
JQuery; a lightweight JavaScript library which makes HTML
document traversal and manipulation, event handling, animation,
and Ajax much simpler. Several JavaScript functions were also
written like to read “.csv” files for the water level forecast and
loading of flood hazard maps and the affected structures and
displaying of the statistics. All map interactions were handled
by Openlayers API like zooming-in and out, to toggle full
screen and especially in showing information when an affected
structure is clicked.
4. WEB INTERFACE
Flood EViDENs can be run using the latest version of several
browsers like Mozilla Firefox, Internet Explorer but we
recommend using Google Chrome. It can be accessed through
this link, http://121.97.192.11:8082/. Figure 3 shows the user
interface of the application as accessed through a web browser.
Basically the user interface of Flood EViDEns is composed of
three (3) major parts or panel; the Query panel, Map panel and
the panel for filtering Flood Hazard Information (Figure 4).
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
This contribution has been peer-reviewed.
https://doi.org/10.5194/isprs-archives-XLII-2-W7-91-2017 | © Authors 2017. CC BY 4.0 License.
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Figure 3. The Flood EViDENs graphical user interface.
Figure 4. Major panels of the Flood EViDENs GUI.
The Query Panel mainly controls the flood hazard and water
level information that you want to be displayed. This also
controls the visualization of flood hazard maps and the affected
structures. The panel contains options, checkboxes and a Go
button. Mainly, these are the necessary inputs needed for the
system run a query.
Select Locality consists of options/dropdown list of
the river basins in which these are the project area of
CSU Phil-LiDAR 1.
Select Flood Event this depends on the selected
locality or river basin; contains available historical
and hypothetical flood events.
Show Flood Hazard Stats if checked, it will display
flood hazard information depending on the selected
locality and flood event.
Show Flood Map if checked, it will display flood
hazard map on the map panel depending also on the
selected locality and flood event.
Show Affected Building and Structures if checked,
it will display the affected buildings and structures on
the map panel depending on the selected locality and
flood event.
The 'Filter Flood Hazard Information’ panel consists of select
option for municipality, barangay under it, building types and a
search button. Depending on the select river basin, a dropdown
list of municipality within it will populate the option. Barangay
option also depends on the selected municipality.
Depending on the query, map visualization will be displayed on
the ‘Map’ panel. It has also map controls and a button to export
it (does not include Google Map base layer) and works by
clicking it (Figure 5).
Figure 5. Map Controls
5. EXAMPLE APPLICATION
The screen shots shown in the following figures show the
results of applying Flood EViDENs for Tropical Storm
‘Seniang’ flood event visualization and damage estimations in
the Bislig River Basin in Surigao del Sur.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
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Figure 6. A table containing the total number of affected structures per barangay according to hazard level that is generated when
Flood EViDEns is used to generated hazard statistics.
Figure 7. A more detailed information (like the building name of the affected structures) can be displayed in Detailed Flood Hazard
Information Panel.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
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Figure 8. A graph can also be generated based on the computed flood hazard statistics.
Figure 9. Map showing flood extent and hazard levels, including the location and description of the affected structure.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
This contribution has been peer-reviewed.
https://doi.org/10.5194/isprs-archives-XLII-2-W7-91-2017 | © Authors 2017. CC BY 4.0 License.
96
6. CONCLUSIONS
In this paper we presented the development, including the
features and functionalities, of an open source web-based flood
hazard information dissemination and analytical system called
“Flood EViDEns”.
The web application made use of various free/open source web
mapping and visualization technologies (GeoServer,
GeoDjango, OpenLayers, Bootstrap), various geospatial
datasets including LiDAR-derived elevation and information
products, hydro-meteorological data, and flood simulation
models to visualize various scenarios of flooding and its
associated damages to infrastructures. The Flood EViDEns
application facilitates the release and utilization of this flood-
related information through a user-friendly front end interface
consisting of web map and tables.
The information provided by Flood EViDEns is very important
as it can increase awareness and responsiveness of the
communities residing in a certain barangay to the impending
flood disaster. Providing this kind of information during a
heavy rainfall event is useful as it could assist in preparation for
evacuation, in easily identifying areas that need immediate
action, in identifying areas that should be avoided, and in
estimating the severity of damage to people and infrastructure as
flooding progresses.
A public version of the application can be accessed at
http://121.97.192.11:8082/. The application is currently being
expanded to cover additional sites in Mindanao, Philippines
through the “Geo-informatics for the Systematic Assessment of
Flood Effects and Risks for a Resilient Mindanao” or the “Geo-
SAFER Mindanao” Program.
ACKNOWLEDGEMENTS
This work is one of the extended R&D activities of the Geo-
SAFER Mindanao (“Geo-informatics for the Systematic
Assessment of Flood Effects and Risks for a Resilient
Mindanao”), a research program supported and funded by the
Philippine Council for Industry, Energy and Emerging
Technology Research and Development of the Department of
Science and Technology (PCIEERD DOST). We gratefully
acknowledge PCIEERD DOST for the financial support. We
would also like to thank the anonymous reviewers for their
helpful comments and suggestions.
REFERENCES
Makinano-Santillan, M., Santillan, J.R., 2015. Flood hazard
mapping of river basins in Caraga Region, Mindanao,
Philippines through the CSU Phil-LIDAR 1 Project. In: 36th
Asian Conference on Remote Sensing, Quezon City, Metro
Manila, Philippines.
Santillan, J.R., Morales, E.M.O., Makinano-Santillan, M., 2015.
Flood EViDEns: a web-based application for near-real time
flood event visualization and damage estimations. In: 36th
Asian Conference on Remote Sensing, Quezon City, Metro
Manila, Philippines.
.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017
ISPRS Geospatial Week 2017, 18–22 September 2017, Wuhan, China
This contribution has been peer-reviewed.
https://doi.org/10.5194/isprs-archives-XLII-2-W7-91-2017 | © Authors 2017. CC BY 4.0 License.
97
ResearchGate has not been able to resolve any citations for this publication.
Conference Paper
Full-text available
In this paper, we share our activities and recent accomplishments in utilizing high spatial resolution Light Detection and Ranging (LiDAR) datasets and other geospatial datasets and techniques for flood hazard mapping of river basins in Caraga Region, Mindanao, Philippines through the CSU Phil-LiDAR 1 project. CSU Phil-LiDAR 1 is one of several projects under the " Phil-LiDAR1: Hazard Mapping of the Philippines using LiDAR " program initiated and supported by the Department of Science and Technology (DOST). Projects under this program are being implemented nationwide by fifteen (15) higher education institutions (HEIs) for 3 years starting 2014. An extension of the University of the Philippines' Disaster Risk Exposure Assessment for Mitigation (DREAM) program, Phil-LIDAR 1′s purpose is for HEIs to utilize LiDAR datasets to generate flood hazard maps of their assigned project areas which are distributed throughout the Philippines. CSU Phil-LiDAR 1 in particular aims to derive Digital Surface Models (DSMs) and Digital Terrain Models (DTMs) from preprocessed LiDAR data, and to utilize these elevation datasets, together with data gathered from field surveys (cross-sections, bathymetry and hydrology) as inputs in the development of flood models. The flood models are then used to generate flood hazard maps of the river basins and watersheds of Caraga Region. Two of the major outputs of the projects during the first two years of its implementation are 1-m resolution LiDAR DTMs and DSMs of the project areas. From these datasets, we were able to generate a risk exposure database consisting of buildings, roads, bridges and other structures. More importantly, we were able to develop flood models and generate detailed flood hazard maps. The said models were also used to reconstruct recent flooding events in the project areas. Other project outputs include near-real time flood extent mapping and water level forecasting which are useful for flood disaster preparedness, prevention and response.
Conference Paper
Full-text available
The Web-based Near-real Time Flood Event Visualization and Damage Estimations (Flood EViDEns) is an online geo-visualization application developed through the Phil-LiDAR 1 project of Caraga State University. The application is targeted to be utilized by the Local Government Units (LGUs) and communities in the Caraga Region, Mindanao, Philippines to assist them in geospatially informed decision making in times of flood disasters. The application is an amalgamation of web mapping technology, various geospatial datasets including LiDAR-derived elevation and information products, hydro-meteorological data, and flood simulation models to visualize in near-real time the current and possible future extent of flooding and its associated damages to infrastructures. The Flood EViDEns application facilitates the release and utilization of this near-real time flood-related information through a user-friendly front end interface consisting of web map and tables. The application's back-end consists of computers running flood simulation models and geospatial analysis to dynamically produce (in an automated manner) current and future flood extents, and tabulated information on the structures affected by flooding including hazard types. These outputs are forwarded into a PostgreSQL/PostGIS spatial database where it is accessed by the front end interface for web visualization. The information provided by Flood EViDEns is very important especially to the LGUs and the community as it can increase awareness and responsiveness of the public to the impending flood disaster. Providing this kind of information during a heavy rainfall event is useful as it could assist in preparation for evacuation, in easily identifying areas that need immediate action, in identifying areas that should be avoided, and in estimating the severity of damage to people and infrastructure as flooding progresses.
The International Archives of the Photogrammetry
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-2/W7, 2017 ISPRS Geospatial Week 2017, 18-22 September 2017, Wuhan, China