Learning Objectives
InaSAFE provides overviews of potential disaster scenarios, of their outcomes, as well as map which can aid decision makers when disaster strikes. In this chapter we will learn about how to use InaSAFE along with other usefull features in InaSAFE for flood hazard scenario. If you interest to learn more about InaSAFE with other hazard beside flood, you go and learn in InaSAFE website.
Let’s begin by reviewing the inputs and outputs of InaSAFE – hazard; exposure; and impact. These terms are important for you to remember because the analysis process depend on these three things.
Hazards (also called disasters) are what we call the data layers that describe the extent and magnitude of natural events (such as earthquakes, tsunamis, volcanic eruptions) that could potentially cause an event or series of events that threaten and disrupt the lives and livelihoods of people.
In general, the hazards data we use in InaSAFE represents a single hazard scenario. A scenario means that the hazard:
Exposure data represents things that are at risk when faced with a potential hazard. This can be man-made features such as public buildings, houses, roads and bridges, or it can be so-called natural features, such as population, rice paddies and lakes. These exposed elements can be divided into various categories, including physical elements (houses, power lines), economic elements (agricultural land, access to employment), social elements (vulnerable groups, population count), and environmental elements (air, water, plants and animals).
Impact is the result we get after InaSAFE processes the effect of the hazard data upon the exposure data. For example, if there is an earthquake model in Lembang, and we process it against building data in Bandung, our impact layer may show those houses that would be severely damaged, those somewhat damaged, and those mildly damaged. In other words, what goes in to InaSAFE are hazards and exposure. What comes out is impact.
Before we run any scenarios, let’s take a closer look at the InaSAFE interface.
Note
Just like QGIS toolbars, you can drag and drop the InaSAFE dock panel to change its position on the QGIS interface. You can pull it away as a separate window, or place it below the Layers panel. It’s convenient in its location on the right side of QGIS, so we will leave it there.
The InaSAFE panel consists of three parts: Questions, Results and Buttons. The questions are mixed in with dropdown boxes - this is where we establish our input data and define the scenario that we want InaSAFE to process. The purpose of InaSAFE is to make your impact analysis very simple and easy to do. The Questions section provides a simple way for you to formulate what you want to know. All questions are created in the following format:
In the event of [hazard] how many [exposure] will be affected?
For example: “In the event of an earthquake how many buildings will be affected?”
The Results section is filled in with information after InaSAFE is run, as we shall see. The buttons at the bottom allow us to run a scenario, print and access help.
We will learn about how to use InaSAFE to run impact scenario based on Infrastructure data. Before we start, let’s find out how to add hazard data first. Hazards can be represented by vector layers or by raster layers. Remember that raster layers are like images with many pixels, and each pixel represents some data about an area on the ground. A raster that shows elevation, for example, will contain pixels with different values based on the altitude of the location. Similarly, a raster that represents a flood will contain the depth of the flood in every pixel in the raster.
Let’s begin by adding our hazard layer to QGIS. It’s a raster model of flood in Jakarta.
You will notice that the hazard drop-down box has been automatically filled in the InaSAFE panel. This is because the data file has already been prepared for us with keyword metadata (fancy words for settings) that tells InaSAFE whether it’s a hazard or exposure layer. When we add the exposure data, we will learn how to add these InaSAFE keywords ourselves.
We can get the data from OpenStreetMap using OpenStreetMap Downloader. We will get any OpenStreetMap data based on the current map extent in QGIS. If your map extent displaying Indonesia, that will take a while to download it since there will be a whole lot of OpenStreetMap data. It would be better to zoom in in specific location to minimize the bandwidth. Let’s learn how to use OpenStreetMap Downloader in QGIS to get OpenStreetMap data.
In order for InaSAFE to know that our layers are hazard or exposure datasets, we need to assign keywords to the layers using the InaSAFE keyword tool. Let’s take a look at the keywords that have already been created on the hazard layer.
If you have a laptop with small RAM, run InaSAFE for large area with so many data will take a long time to finish. To solve the problem, we can set the analysis area to a smaller area to make the analysis quicker.
Green box will appear around the map canvas.
This green box is the analysis area. InaSAFE will calculate all the data inside the green box.
Now our hazard and exposure data are set in the InaSAFE panel, because the appropriate keywords have been added to our layers. Note that if we were to add a second exposure layer to our project, we would be able to choose which exposure layer we wanted from the InaSAFE drop-down menu. The same applies to hazard layers.
The third drop-down box is the impact function. This concludes our question, and defines the function that InaSAFE will run behind the scenes. InaSAFE developers have written many of these functions to analyse all sorts of hazard and exposure layers. The function that is selected for us here will process the hazard and exposure layers spatially to determine how the exposure layer will “be flooded.”
Click the Run button at the bottom to start the impact analysis. At the end of the process, the statistics will be displayed in the Results section, and a new layer will be added to the Layers panel that describes the result of the analysis. The map will show which buildings that are affected and which are not.
In this section we will learn how to run impact analysis for population data with InaSAFE. We are going to use the same raster hazard data for flood in Jakarta and we will add another exposure data: population from AsiaPop.
We have already learned about how to change the symbol for this data in previous chapter (chapter 6), so if the appearance of this AsiaPop’s data is different than yours, you may need to change it.
We can use InaSAFE to give impact result according to the whole area or divide it by administrative boundary. InaSAFE will provide impact analyst result for each administration area that we provide. This method will help us to know the result specifically for each area, so we are able to know how many people that might be affected and how many logistic we should prepare for each administration area. To do this, we need to define aggregation layer first using Keyword Creation Wizard.
We have already set the analysis area for imapct calculation for the building. This time we will set the analysis area for population data.
Green box will appear around the map canvas.
This green box is the analysis area. InaSAFE will calculate all the data inside the green box.
You will get impact result in the InaSAFE panel in the right side divided by 5 municipal in Jakarta.
When you scroll impact result from running InaSAFE scenario, you will notice that there are some statistic that show how many rice, drinking water, clean water, family kits and toilet for each municipals in Jakarta. It’s called minimum needs per week for each people evacuated. The purpose of this minimum needs is to provide quick method calculating support requirements (in terms of food, water, etc) for displaced persons.
The minimum needs (by default) are based on ‘Perka 7/2008’ BNPB according to the following default formulas:
If you are not satisfied with these configuration, you can define your custom minimum needs for your own area using Minimum Needs Configuration
button in the right upper side of the window.
After creating your custom minimum needs you can run InaSAFE with your own minimum needs:
The data displayed on the screen can be saved to a PDF file by clicking Print at the bottom of the InaSAFE panel.
You can save the impact layer that InaSAFE created, and you can save the QGIS project to come back to it later, but note that the InaSAFE’s symbology style cannot be saved. It will show you only black and white layer and you need to symbolise again.
To get the style from your InaSAFE result, you need to save the InaSAFE result’s style first.
After you saved your InaSAFE result style now you can save your InaSAFE result layer and get the same style like the InaSAFE Result.
Now you have learned about how to use InaSAFE from using InaSAFE Keyword Wizard to define keyword attribute, how to run InaSAFE with InaSAFE dock and Impact Function Wizard, how to modify minimum needs, and how to use OSM Downloader to download OpenStreetMap data directly. InaSAFE is really helpful for us to know the impact of disaster and how we can create some plans if the disaster were to happen in real life.