QGIS Trigger Workflow for Somalia#

The QGIS workflow presented in this article was developed in the framework of the Forecast-based-Action (FbF) Project of the Somalia Red Cresent Society (SRCS), the German Red Cross (GRC) and the Heidelberg Institute for Geoinformation Technology (HeiGIT).

The workflow consists of 15 steps of which 9 are automated in the form of a QGIS Model. In this article, we explain how all 15 steps can be done manually. In practice one needs to do only 6 steps manually, the rest is done by the QGSI Model. The chapter Workflow Automated explains the process and how it is intended in practice. The chapter Workflow Manually is to understand what happens inside of the QGIS Model.

Background#

Setting triggers is one of the cornerstones of the Forecast-based Financing system. For a National Society to have access to automatically released funding for their early actions, their Early Action Protocol needs to clearly define where and when funds will be allocated, and assistance will be provided. In FbF, this is decided according to specific threshold values, so-called triggers, based on weather and climate forecasts, which are defined for each region (see FbF Manual).

For the development of the Somaliland-Somalia Drought Trigger mechanism various datasources were thoroughly analysed. Finally, the main parameters chosen for the trigger based on the historical impact assessment are the twelve month Standard Precipitation Index (SPI12) and the IPC acute food insecurity classification. The exact data used are the documented and forecasted SPI12 (source: ICPAC) and the forecasted IPC classification (8 month forecast, source: FEWSNET), that is used to calculate a population weighted index of food insecurity. The trigger thresholds for both components were optimised towards the most favourable proportion of hit rate and false alarm rate. The emerging thresholds were <-1 for the SPI12 and >=0,7 for the IPC based index. The triggering is done on district level and per district just one trigger initiation per year is possible.

Trigger Statement#

When ICPAC issues a SPI-12 forecast of less than -1 for a district AND the current FEWSNET food insecurity projection reaches at least 0.7 in its derived population weighted index in the same district, then we will act in this district. We expect the lead-time to be 90 days.

Trigger Input Data#

For the trigger mechanism to work properly we currently use different datasets: data that we assume to be fixed in the near term, and variable data which describe the datasets that will be checked for triggering on a monthly base.

Fixed Data#

By fixed data we mean datasets that are needed for the trigger to work, that will most probably not change in the near term. In the long term these datasets can be adapted easily.

Dataset

Source

Description

Adminstrative bounderies

HDX

The administrative bounderies on level 0-2 for Somalia and Somaliland can be accessed via HDX. For this trigger mechanism we provide the administrative bounderies on level 2 (district level) as a shapefile. We have added the population number for each district derived from Worldpop.

Population Counts

Worldpop

The worldpop dataset in .geotif rasterformat provides population estimates per hectar for the year 2020

Monitoring Data#

The drought trigger mechanism is based on two variable monitoring datasets updated monthly: The SPI-12 forecast produced by ICPAC and the Food Insecurity projection produced by FEWSNET. The SPI-12 is used to capture hazard forecasts while the Food Insecurity Projection captures the dynamic vulnerability. In this way upcoming drought events (SPI) that most probably will lead to food insecurity (IPC) will be captured.

Dataset

Source

Description

SPI-12 forecast

ICPAC

meteorological drought indicator to monitor precipitation anomalies over 12-month accumulation periods

IPC Projections

FEWSNET

five-phase scale providing common standards for classifying the severity of acute or anticipated acute food insecurity.

What is the Standarized Precipitation Index (SPI-12)?#

The Standardized Precipitation Index (SPI) is a widely used index to characterize meteorological drought. The Standarized Precipitation Index (SPI-12) compares the total rainfall received at a particular location during the last 12 months with the long-term rainfall mean (42 years) for the same period of time at that location.

What is IPC Food Security Projection Data?#

The IPC is a commonly acceepted measure and classification to describe the current and anticipated severity of acute food insecurity. The classification is based on a convergence of available data and evidence, including indicators related to food consumption, livelihoods, malnutrition and mortality. Food Insecurity is one of the prioritized impacts of droughts in Somalia which is why it is also used for the triggering mechanism, in a population-weighted index.

Colour

Phase

Descriptions

1. Minimal

Households are able to meet essential food and non-food needs without engaging in atypical and unsustainable strategies to access food and income.

2. Stressed

Households have minimally adequate food consumption but are unable to afford some essential non-food expenditures without engaging in stress-coping strategies.

3. Crisis

Households either have food consumption gaps that are reflected by high or above-usual acute malnutrition OR are marginally able to meet minimum food needs but only by depleting essential livelihood assets or through crisis-coping strategies.

4. Emergency

Households either have large food consumption gaps which are reflected in very high acute malnutrition and excess mortality; OR are able to mitigate large food consumption gaps but only by employing emergency livelihood strategies and asset liquidation.

5. Famine

Households have an extreme lack of food and/or other basic needs even after full employment of coping strategies. Starvation, death, destitution, and extremely critical acute malnutrition levels are evident. (For Famine Classification, area needs to have extreme critical levels of acute malnutrition and mortality.)

IPC Food Security Projection:#

Three times a year (February, June, and October) FEWSNET estimates most likely IPC classes for the upcoming 8 month (near-term and mid-term projection), available from 2019-current. The near-term projection is called ML1 and is a projection for the upcoming 4 month, the mid-term projection is called ML2 and projects the IPC classes for the 4 subsequent months. For the triggering ML1 (near-term) as well as ML2 (mid-term) projections will be considered.

Outlook updates are produced almost every month and are also taken into account.

IPC-Population Weighted Index#

To better operationalise the IPC data a simple population-weigthed index was developed. Relative population numbers are weighted based on the respective IPC class they fallin, in order to give the amount of people in a certain IPC class the importance instead of the IPC class only. Furthermore, population located in a higher IPC class is more important than population located in a lower class. The index is calculated as follows:

\( IPC\ Index = Weights \times \frac{District\ Pop\ per\ IPC\ Phase}{Total\ District\ Pop}\)

Where the weights are defined as:

IPC Pahse

Weight

IPC 1

0

IPC 2

0

IPC 3

1

IPC 4

3

IPC 5

6

The IPC Index represents low-population districts equal to high-population districts. No underrepresentation of high food insecurity of small districts occurs.

Trigger Workflow Automated#

As explained in the beginning of this chapter, the 9 main steps of the developed trigger workflow are done automatically by a QGIS model. In the previous chapters you have learned the purpose and needed tools of each step and how to perform them manually. In this chapter it is explained how to run the automated model.

The QGIS Model Designer is a visual tool that allows users to create and edit a workflow with all tools available in QGIS that can be used repeatedly in a simple and time-efficient manner. It provides a graphical interface to build workflows by connecting geoprocessing tools and algorithms. The user can define inputs, outputs, and the flow of data between different processing steps.

Step 1: Setting up folder structure#

../../_images/Drought_EAP_Worklow_Step_1_1.png

Purpose: In this step we set up the correct folder structure to make the analysis easier and to ensure consitent results.

Tool: No special tools or programs are needed

Instruction

Folder Structure

  1. Open the Folder “FbF_Drought_Monitoring_Trigger”

  2. Open the subfolder “Monitoring”

  3. Copy the Template folder “TEMPLATE_Year_Month” and change the name to the current year and month. The result could be the folder “2022_05”
../../_images/Folder_structure_FbF_Drought_Monitoring_Trigger.drawio.svg

The Video below shows the process for setting up the folder for decmber 2023.

Video: Setting up folder structure

Step 2: Download of the forecast data#

../../_images/Drought_EAP_Worklow_Step_2_2.png

Tool: FileZilla and Interent Browser

The current plans provide that ICPAC will monthly provide the SPI-12 forcast whereas the IPC data will be pulled from the FEWSNET website. FEWS NET publishes IPC data on its website. The main data publications plus the updates of the IPC data amount to the publication of new data almost monthly.

SPI-12 Data#

ICPAC will provide the SPI-12 forecasts on their FTP (File Transfer Protocol). There are different ways to access the FTP-Server. We recommend to install and once set up FileZilla. This will make your work easily repeatable on a monthly basis.

  1. Download Filezilla here.

  2. Install the .exe file you have downloaded

  3. Open FileZilla

  4. Establish a connection to the FTP Server by insterting the credentials you have been passed (Host, Username and Password) and clicking Quickconnect.

In FileZilla you have four windows. On the left hand side you will see the folder on your computer in the upper window. By clicking on a folder, the documents in the folder will be shown in the lower left window. On the right hand side, you will see in the upper window the FTP data folder and by clicking on it, the data will be shown in the lower right window.

In order to pass the data from the FTP Server to your own machine you can simply drag and drop the folder or data from the righthandside windows (FTP-Server) to the lefthandside windows (your Computer). To do so, firstly navigate to your folder where you wneed the latest SPI-12 data to be located .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/SPI_12. Then drag and drop the latest SPI-12 into the folder.

../../_images/FileZilla.PNG

IPC Data#

The IPC Projection data is provided and regulary updated on the FEWSNET Website. On the website you will have to click on Somalia to acess the data. Alternativley, you can navigate through Data -> Acute Food Insecurity Data and enter „Somalia”. In the menu you will see different dataformats for different timestamps. Once you find out which timestamp is the most current one find the ZIP download. We need the data in shapefile (.shp) format, which is only included in the ZIP file and not provided as single download file.

Warning

The FEWSNET pages change often !

  1. Go to FEWSNET Website. Click on Data -> Acute Food Insecurity.

  2. Scroll down. In Geograhic Area typ in “Somalia” and click Apply

  3. Choose the newest dataset.

../../_images/IPC_Projections_website.png

  1. Download the one with the ZIP Data

  2. When you have downloaded the data, right-click on the file and click on Extract all -> Extract

  3. Open the extracted folder and copy the ML1 data in the IPC_ML1 folder you have created in step 1.

  • The filename is composed of “SO” for Somalia, year and month of the report month e.g SO_202308_ML1.shp Example path: .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/IPC_ML1

  1. Copy the ML2 data into IPC_ML2 folder you have created in step 1.

  • The filename is composed of “SO” for Somalia, year and month of the report month e.g SO_202308_ML2.shp Example path: .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/IPC_ML2

Warning

Make sure to not use the ML1_IDP data which comes in the .zip folder as well!

Warning

Remember that you need to copy over all components that the respective shapefile is composed of. Most probably it has 5 components: .cpg, .dbf, .prj, .shp, and .shx.

../../_images/IPC_zip.PNG

Tip

On the main FEWSNET page you can also sign up for information on latest updates via email. For this option scroll down to the end of the page and click on Sign up for Emails. You will then get the option to choose updates only for Somalia.

../../_images/IPC_Newsletter.png

Step 3: Loading data into QGIS#

../../_images/Drought_EAP_Worklow_Step_3_1.png

Purpose: In this step, all the data needed will be loaded into QGIS.

Tool: No specific tools are needed, only QGIS.

  1. Open QGIS and create a new project by clicking on Project -> New

  2. Once the project is created save the project in the folder you created in Step 1 (e.g. 2022_05). To do that click on Project -> Save as and navigate to the folder. Give the project the same name as the folder you created (e.g. 2022_05). Then click Save

  3. Load all input data in QGIS by drag and drop. Click on Project -> Save

  • From the folder you created in step 1

    • ML1

    • ML2

    • SPI-12

  • From the Fixes_data folder:

    • district_pop_som

    • Regions

    • risk_assessment.gpkg

    • WorldPop_som.tif

Result: QGIS project with all necessary data ready to be analysed.

This video shows how to setup the QGIS project for April 2022 and how to import all data into the project.

Video: Loading data into QGIS

Step 4: Load the model in the QGIS Model Designer#

../../_images/Drought_EAP_Worklow_Step_4_1_automated_model.png

  1. Open the tool under Processing -> Graphical Modeler

  2. In the upper panel click Model -> Open Model and naviageto your folder “FbF_Drought_Monitoring_Trigger”, mark the “Triggermodel_Somalia.model3” file an click on Open. The model will open and you will see yellow, white and green boxes.

Video: Open Model

../../_images/Model_Designer.PNG

Box

Significance

Description

Yellow

Model Input

Definition of the Inut data for the model the model will perform on

White

Algorithms

Algorithms or Tools are specific geoprocessing steps that perform specific tasks, such as clipping, reprojecting or buffering.

Green

Model Output

The results created by the model (Output layers) are automatically added to your layers panel in your QGIS project interface

Step 5: Run the model#

../../_images/Drought_EAP_Worklow_Step_5_1_automated_model.png

Model Input & Output

Attention

In the dropdown list, only layers that are currently loaded in your QGIS Project will be displayed.

For each of these mandatory inputs, you click on the dropdown arrow and choose the respective file. The model needs the follow 5 inputs:

  1. In the upper panel click on Model -> Run Model. A window will open where you need to define the model input and output.

  2. The model needs the follow 5 inputs:

    1. IPC_Projection_ML1: ML 1 data

    2. IPC_Projection_ML2: ML 2 data

    3. Pop_per_district: district_pop_sum

    4. SPI12 (SPI12 forecast): SPI-12 data

    5. Worldpop (Population Raster data): Worldpop data

  3. Futherdown you have to specify where to save the output:

    1. Trigger_activation: Click on the three points -> Save to File and navigate to Resultsfolder in the folder you created in step 1 (Year_month). Give the output the name:

    Trigger_activation

    1. ML2_ML1_Indices_joined: Click on the three points -> Save to File and navigate to Resultsfolder in the folder you created in step 1 (Year_month). Give the output the name:

    ML2_ML1_Indices_joined

    1. SPI12_mean_IPC_Indices_joined:Click on the three points -> Save to File and navigate to Resultsfolder in the folder you created in step 1 (Year_month). Give the output the name:

    SPI12_mean_IPC_Indices_joined

  4. Click Run. Your results layer will appear in the main QGIS window. You can close the graphical modeller window.

Video: Input and output Model

../../_images/SRCS_Model_input.png

Step 6.: Visualisation of results#

../../_images/Drought_EAP_Worklow_Step_14_1.png

Purpose: Definition of how features are represented visually on the map.

Tool: Symbology

Trigger Activation

  1. Right cklick on the “Trigger_activation” layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “Style_Trigger_Activation.qml”.

  4. Click Open. Then click on Load Style

  5. Back in the “Layer Properties” Window click Apply and OK

Info: Trigger Activation Layer

You will now see districts where no trigger is activated in green and districts with trigger activation in pink.

The “Style_Trigger_Activation.qml” style layer is configured to show the district names only where the trigger is actually activated. If there is no trigger activation you can activate the admin 1 boundary layer for better map orientation (see Administrative 2 Boundaries below)

../../_images/Map_yes_trigger.PNG

Risk Assessment

  1. Right click on the “risk_assessment_districts” layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “somalia_risk_assessment_style.qml” style layer.

  4. Move the “risk_assessment_district” layer below “Trigger_Activation” layer (Layer Concept).

  5. Back in the “Layer Properties” Window click Apply and OK

Info: Risk Assessment Layer

For the creation of an Intervention Map we will have to add the risk assessment data and the respective style file. For this first of all load from “FbF_Drought_Monitoring_Trigger/Fixed_data/Risk_Assessment” the file “risk_assessment_districts.gpkg”. This file is the output of the conducted risk assessment and contains a risk value for each district of Simaliland and Somalia. In order to visualize it

Administrative 2 Boundaries (Regions)

  1. Right click on the “Som_Admbnda_Adm1_UNDP” (Regiond) layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “somalia_risk_assessment_style.qml”.

  4. Click Open. Then click on Load Style

  5. Back in the “Layer Properties” Window click Apply and OK

  6. Add a the OpenStreetMap basemap by clicking on Layer -> Add Layer -> Add XYZ layer... -> Select the OpenStreetMap. Click Add. (Wiki basemap)

  7. Place the OpenStreetMap basemap on the bottom.

  8. Delet all layers exept:

    • Trigger_activation

    • risk_assessment_districts

    • Som_Admbnda_Adm1_UNDP

    • OpenStreetMap

Video: Visualisation of results

Intervention Map without Trigger activation

Intervention Map with Trigger activation
../../_images/Map_no_trigger.PNG
../../_images/Map_yes_trigger.PNG

Attention

Remember the layer concept and make sure the basemap layer is at the bottom of your layers panel.

Step 7: Making print map#

../../_images/Drought_EAP_Worklow_Step_15_1.png

Purpose: Viualization of the map features in a printable map layout

Tool: Print Layout

  1. If not done before, delet all layers expect Trigger_activation, risk_assessment_districts and OpenStreetMap

  2. Open a new print layout by clicking on Project -> New Print Layout -> enter the name of your current Project e.g “2022_04”.

  3. Go the the FbF_Drought_Monitoring_Triggerfolder and drag and drop the fileTrigger_activation_Intervention_map.qpt` in the print layout

  4. Change the date to the current date by clicking on “Further map info…” in the items panel. Click on the Item Properties tab and scroll down. Here you can change the date in the Main Properties field.

  5. Adjust the Lgend by clicking on the legend in the Item Properties tab and scroll down until you see the Legend items field. If it is not there check if you have to open the dropdown. Make sure Auto update is not checked.

    • Remove all itemes in the legend be clicking on the item and then on the red minus icon below.

    • Add Trigger_activation and risk_assessment_districts to the legend by clicking on the green plus and click on the layer and click ok

Video: Making print map

Attention

Make sure you edit the Map Information on the template, e.g. current date. Also make sure to check the legend items: Remove unnecessary items and eventually change the names to meaning descriptions.

In order to easily visualize the output of the trigger analysis we provide you with a map template that can be used as a base for your visualization. You can find the template in the following directory: “…/FbF_Drought_Monitoring_Trigger/maps_somalia_template_risk_assessment.qpt”.

You can also adapt the template to your needs and preferences. You can find help here.

Attention

Make sure you edit the Map Information on the template, e.g. current date. Also make sure to check the legend items: Remove unnecessary items and eventually change the names to meaning descriptions.

Step 8.: Exporting Map#

../../_images/Drought_EAP_Worklow_Step_16_1.png

Purpose: Export the designed and finalized map layout in order tp print it as a pdf or format of your choice.

Tool: Print Layout

When you have finished the design of you map you can export it as pdf or image file in different datafromats.

Export as Image

  1. In the print layout click on Layer -> Export as Image

  2. Chose the Result folder in the folder you have created in step 1. Give the file the name of the project e.g 2022_04

  3. Click on Save

  4. The window “Image Export Options” will appear. Click Save Now the image can be found in the result folder in the folder you created in Step 1

Export as PDF

  1. In the print layout click on Layer -> Export as PDF

  2. Chose the Result folder in the folder you have created in step 1. Give the file the name of the project e.g 2022_04

  3. Click on Save

  4. The window “PDF Export Options” will appear. For the best results, select the lossless image compression.

  5. Click Save Now the image can be found in the result folder in the folder you created in Step 1

Video: Export image and PDF

../../_images/map_output_example2.png

Trigger Workflow Manually#

Step 1: Setting up folder structure#

../../_images/Drought_EAP_Worklow_Step_1_1.png

Purpose: In this step we set up the correct folder structure to make the analysis easier and to ensure consitent results.

Tool: No special tools or programs are needed

Instruction

Folder Structure

  1. Open the Folder “FbF_Drought_Monitoring_Trigger”

  2. Open the subfolder “Monitoring”

  3. Copy the Template folder “TEMPLATE_Year_Month” and change the name to the current year and month. The result could be the folder “2022_05”
../../_images/Folder_structure_FbF_Drought_Monitoring_Trigger.drawio.svg

The Video below shows the process for setting up the folder for decmber 2023.

Video: Setting up folder structure

Step 2: Download of the forecast data#

../../_images/Drought_EAP_Worklow_Step_2_2.png

Purpose:

Tool: FileZilla and Interent Browser

The current plans provide that ICPAC will monthly provide the SPI-12 forcast whereas the IPC data will be pulled from the FEWSNET website. FEWS NET publishes IPC data on its website. The main data publications plus the updates of the IPC data amount to the publication of new data almost monthly.

SPI-12 Data#

ICPAC will provide the SPI-12 forecasts on their FTP (File Transfer Protocol). There are different ways to access the FTP-Server. We recommend to install and once set up FileZilla. This will make your work easily repeatable on a monthly basis.

  1. Download Filezilla here.

  2. Install the .exe file you have downloaded

  3. Open FileZilla

  4. Establish a connection to the FTP Server by insterting the credentials you have been passed (Host, Username and Password) and clicking Quickconnect.

In FileZilla you have four windows. On the left hand side you will see the folder on your computer in the upper window. By clicking on a folder, the documents in the folder will be shown in the lower left window. On the right hand side, you will see in the upper window the FTP data folder and by clicking on it, the data will be shown in the lower right window.

In order to pass the data from the FTP Server to your own machine you can simply drag and drop the folder or data from the righthandside windows (FTP-Server) to the lefthandside windows (your Computer). To do so, firstly navigate to your folder where you wneed the latest SPI-12 data to be located .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/SPI_12. Then drag and drop the latest SPI-12 into the folder.

../../_images/FileZilla.PNG

IPC Data#

The IPC Projection data is provided and regulary updated on the FEWSNET Website. On the website you will have to click on Somalia to acess the data. Alternativley, you can navigate through Data -> Acute Food Insecurity Data and enter „Somalia”. In the menu you will see different dataformats for different timestamps. Once you find out which timestamp is the most current one find the ZIP download. We need the data in shapefile (.shp) format, which is only included in the ZIP file and not provided as single download file.

Warning

The FEWSNET pages change often !

  1. Go to FEWSNET Website. Click on Data -> Acute Food Insecurity.

  2. Scroll down. In Geograhic Area typ in “Somalia” and click Apply

  3. Choose the newest dataset.

../../_images/IPC_Projections_website.png

  1. Download the one with the ZIP Data

  2. When you have downloaded the data, right-click on the file and click on Extract all -> Extract

  3. Open the extracted folder and copy the ML1 data in the IPC_ML1 folder you have created in step 1.

  • The filename is composed of “SO” for Somalia, year and month of the report month e.g SO_202308_ML1.shp Example path: .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/IPC_ML1

  1. Copy the ML2 data into IPC_ML2 folder you have created in step 1.

  • The filename is composed of “SO” for Somalia, year and month of the report month e.g SO_202308_ML2.shp Example path: .../FbF_Drought_Monitoring_Trigger/Monitoring/Year_Month_template/IPC_ML2

Warning

Make sure to not use the ML1_IDP data which comes in the .zip folder as well!

Warning

Remember that you need to copy over all components that the respective shapefile is composed of. Most probably it has 5 components: .cpg, .dbf, .prj, .shp, and .shx.

../../_images/IPC_zip.PNG

Tip

On the main FEWSNET page you can also sign up for information on latest updates via email. For this option scroll down to the end of the page and click on Sign up for Emails. You will then get the option to choose updates only for Somalia.

../../_images/IPC_Newsletter.png

Step 3: Loading data into QGIS#

../../_images/Drought_EAP_Worklow_Step_3_1.png

Purpose: In this step, all the data needed will be loaded into QGIS.

Tool: No specific tools are needed, only QGIS.

  1. Open QGIS and create a new project by clicking on Project -> New

  2. Once the project is created save the project in the folder you created in Step 1 (e.g. 2022_05). To do that click on Project -> Save as and navigate to the folder. Give the project the same name as the folder you created (e.g. 2022_05). Then click Save

  3. Load all input data in QGIS by drag and drop. Click on Project -> Save

  • From the folder you created in step 1

    • ML1

    • ML2

    • SPI-12

  • From the Fixes_data folder:

    • district_pop_som

    • Regions

    • risk_assessment.gpkg

    • WorldPop_som.tif

Result: QGIS project with all necessary data ready to be analysed.

This video shows how to setup the QGIS project for April 2022 and how to import all data into the project.

Video: Loading data into QGIS

Step 4: Intersection of ML 1 & ML 2 data with the district polygons#

../../_images/Drought_EAP_Worklow_Step_4_1.png

Purpose: The goal is to receive polygon layers which share both the borders and the attributes of both input layers.

Attention

You need to perform this step two times. One time for ML 1 and a second time for ML 2.

Tool: Intersection

Instruction

Intersection

  1. Click on Vector -> Geoprocessing Tools -> Intersection 2.Input Layer: ML 1 or ML 2

  2. Overlay layer: district_pop_sum

  3. Under Intersection click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “ML1_Intersection” or “ML2_Intersection” and click Save

  4. Click Run
../../_images/SRCS_Trigger_step_4_Intersection.png

Result: After doing this for ML1 and ML2 you should have two polygon layers, each containing all columns of ML1 (or ML2) and district_pop_sum.

Note

The resulting layer can have more rows than the original layers.

The video shows the whole process on the example of ML 1.

Video: Intersection of ML 1 & ML 2 data with the district polygons

Step 5: Calculation of Population per Intersection Polygon#

../../_images/Drought_EAP_Worklow_Step_5_1.png

Purpose: Here we calculate the population in each polygon of the intersection layer from step 4.

Attention

You need to perform this step two times. One time for ML 1 and a second time for ML 2.

Tool: Zonal Statistics

Instruction

Zonal Statistics

  1. In the Toolbox -> Search for Zonal Statistics

  • Tip: If the Toolbox is not opne click Processing-> Toolbox

  1. Input Layer: “ML1_Intersection” or “ML2_Intersection”

  2. Raster Layer: “som_ppp_2020_UNadj_constrained.tif”

  3. Statistics to calculate: Only Sum

  4. Under Zonal Statistics click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “ML1_zonal_statistic” or “ML2_zonal_statistic” and click Save

  5. Click `Run
../../_images/SRCS_Trigger_step_5_zonal_statistic.png

Result: The result should be the “ML1_zonal_statistic” and “ML2_zonal_statistic” polygon layers. These layers should have the same columns in the attribute table plus the column “_sum”, which is the number of people living in the single parts of the polygons.

Video: Calculation of Population per Intersection Polygon

Step 6: Weighting of the Population based on IPC-Phase#

../../_images/Drought_EAP_Worklow_Step_6_1.png

Purpose: The purpose of this step is the weighting of the population in the five IPC phases as described in IPC Data.

Attention

You need to perform this step two times. One time for ML 1 and a second time for ML 2.

Tool: Field Calculator

  1. Right-click on the layer “ML1_zonal_statistic” (or “ML2_zonal_statistic”) -> Open Attribute Table-> click on Field Calculator to open the field calculator

  2. Check “Create new field”

  3. Output field name: Name the new column “pop_sum_weighted”

  4. Result field type: Decimal number (real)

  5. Add the code block from Input into the Expression field Click ok

ML 1

ML 2

 
CASE

WHEN "ML1" = 3 THEN "_sum" * 1
WHEN "ML1" = 4 THEN "_sum" * 3
WHEN "ML1" = 5 THEN "_sum" * 6
ELSE "_sum"

END

CASE

WHEN "ML2" = 3 THEN "_sum" * 1
WHEN "ML2" = 4 THEN "_sum" * 3
WHEN "ML2" = 5 THEN "_sum" * 6
ELSE "_sum"

END

  1. Save the new column by clicking on in the attribute table and end the editing mode by clicking on

Here is the Field Calculator window of how it should look to calculate pop_sum_weighted for ML1.

../../_images/SRCS_Trigger_step_6_field_calculator.png

Result: The two layers “ML1_zonal_statistic” and “ML2_zonal_statistic” should now both have the column “pop_sum_weighted”.

The video shows the whole process with the the example of ML 1.

Video: Weighting of the Population based on IPC-Phase

Step 7: Adding the total district population to Intersection Polygons#

../../_images/Drought_EAP_Worklow_Step_7_1.png

Purpose: Now we want to add a column with the total district population to “ML1_zonal_statistic” and “ML2_zonal_statistic”.

Attention

You need to perform this step two times. One time for ML 1 and a second time for ML 2.

Tool: Join attributes by field value

Instruction

Join attributes by field value

  1. In the Toolbox-> Search for Join attributes by   field value

  • Tip: If the Toolbox is not opne click Processing-> Toolbox

  1. Input Layer: Select “ML1_zonal_statistic” (or “ML2_zonal_statistic”)

  2. Table field: Select “admin2Name”

  3. Input Layer 2: Select the layer “district_pop_som”

  4. Table field 2: Select “admin2Name”

  5. Layer 2 field to copy: Click on the three points and select “admin2Name” and “districtpo”

  6. Join type: Select the option “Take attributes of the first matching feature only (one-to-one)

  7. Under Join Layer [optional] click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “ML1_join” or “ML2_join” and click Save

  8. Click Run
../../_images/SRCS_Trigger_step_7_join.png

Result: Now you should have to new polygon layer named “ML1_join” and ML2_Join” containing the column districtpo.

Video: Adding the total district population to Intersection Polygons

Step 8: Calculation of Population Proportion per Intersection Polygon#

../../_images/Drought_EAP_Worklow_Step_8_1.png

Purpose: In this step we calculating the IPC-Population Weighted Index for every small part of the polygon layer.

Attention

You need to perform this step two times. One time for ML 1 and a second time for ML 2.

Tool:Field Calculator

  1. Right-click on Intersection_population Polygons layer -> “Attribute Table”-> click on Field Calculator to open the field calculator

  2. Check Create new field

  3. Output field name: Name the new column “Index_per_IPCPolygon_ML1” (or “Index_per_IPCPolygon_ML2”)

  4. Result field type: Decimal number (real)

  5. Add the code into the Expression field

"pop_sum_weighted"/"districtpo"

  1. Click ok

  2. Save the new column by clicking on in the attribute table and end the editing mode by clicking on

../../_images/SRCS_Trigger_step_8_field_calculator.png

Result: Both layer “ML1_join” and ML2_Join” should now have the column “Index_per_IPCPolygon_ML1” or “Index_per_IPCPolygon_ML2”. The numbers in this column have to be smaller than in the “district” column.

The video shows the whole process with the the example of ML 1.

Video: Calculation of Population Proportion per Intersection Polygon

Step 9: Calculate IPC Index per District#

../../_images/Drought_EAP_Worklow_Step_9_1.png

Purpose: The purpose of this step is to calculate a population weighted mean over the IPC classes that fall within a district, in order to give the amount of people living in a certain IPC class more importance than just the area affected by a certain IPC class. The result is a IPC Index value for each district.

Tool: Join attribute by location (summary)

Instruction

Join attribute by location (summary)

  1. In the Toolbox-> Search for Join attribute by location (summary)

  • Tip: If the Toolbox is not opne click Processing-> Toolbox

  1. Input Layer: Select your “district_pop_som” layer

  2. Input Layer 2: Select “ML1_join” (or ML2_Join”)

  3. Geometric predicate: Select “Intersection”

  4. Field to summarise: Select “Index_per_IPCPolygon_ML1” (or “Index_per_IPCPolygon_ML2” )

  5. Summaries to calculate: Chose only the option “mean”

  6. Under Join Layer click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “ML1_join_location” or “ML2_join_location” and click Save

  7. Click Run
../../_images/SRCS_Trigger_step_9_join_location.png

Result: As a result, your two layers “ML1_join_location” and “ML2_join_location” should have the column “Index_per_IPCPolygon_ML1_mean” or “Index_per_IPCPolygon_ML2_mean”. Furthermore, the number of rows should be the exact number of districts in Somalia and the polygons should have the exact shape of the districts.

Video: Calculate IPC Index per District

Step 10.: Join ML1 and ML2#

../../_images/Drought_EAP_Worklow_Step_10_1.png

Purpose: The purpose of this step is to merge “ML1_join_location” and “ML2_join_location” into one layer so we have the IPC-Index for all districts.

Tool: Join attributes by field value

Instruction

Join attribute by location (summary)

  1. In the Toolbox-> Search for Join attributes by field value

  • Tip: If the Toolbox is not opne click Processing-> Toolbox

  1. Input Layer: Select your “ML1_join_location” layer

  2. Table field: Select “admin2Name”

  3. Input Layer 2: Select your “ML2_join_location” layer

  4. Table field 2: Select “admin2Name”

  5. Layer 2 field to copy: Click on the three points and select “Index_per_IPCPolygon_ML2_mean”

  6. Join type: Select the option “Take attributes of the first matching feature only (one-to-one)

  7. Under Join Layer click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “IPC_index_district” and click Save

  8. Click Run
../../_images/SRCS_Trigger_step_10_IPC_Index_district.png

Result: Layer with the districts of Somalia and the IPC-Index of each district.

Video: Join ML1 and ML2 I

Step 11: Calculation of SPI-12 Mean per District#

../../_images/Drought_EAP_Worklow_Step_11_1.png

Purpose: Calculate the mean value over the SPI-12 values of all pixels that fall within a scertain districts area, in order to have one SPI-12 value for each district.

Tool: Zonal Statistics

Instruction

Zonal Statistics

  1. In the Toolbox -> Search for Zonal Statistics

  • Tip: If the Toolbox is not open click Processing-> Toolbox

  1. Input Layer: district_pop_som

  2. Raster Layer: SPI Forecast

  3. Output column prefix: Use “SPI12_”

  4. Statistics to calculate: “Mean”

  5. Under Zonal Statistics click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “SPI12_district” and click Save

  6. Click `Run``
../../_images/SRCS_Trigger_step_11_IPC_zonal_district.png

Result: A layer of all districts of Somalia with the mean SPI-12.

Video: Calculation of SPI12 Mean per District

Step 12: Join SPI-12 Mean to the IPC Index#

../../_images/Drought_EAP_Worklow_Step_12_1.png

Purpose: The purpose of this step is to merge data from two different data sources into one data frame so that it can be jointly analysed.

Tool:Join attributes by field value

Instruction

Join attributes by field value

  1. In the Toolbox-> Search for Join attributes by field value

  • Tip: If the Toolbox is not opne click Processing-> Toolbox

  1. Input Layer: Select your “IPC_index_district”

  2. Table field: Select “admin2Name”

  3. Input Layer 2: Select your “SPI12_district”

  4. Table field 2: Select “admin2Name”

  5. Join type: Select the option “Take attributes of the first matching feature only (one-to-one)”

  6. Under Join Layer click on the three points -> Save to File and navigate to you monitoring folder [Year_Month]. Give the output the name “IPC_index_SPI_12_district” and click Save

  7. Click Run
../../_images/SRCS_Trigger_step_12_IPC_SPI12_join.png

Result: The result will be a layer of all districts of Somalia with the mean SPI-12 and the IPC-Index of each district.

Video: Join SPI12 Mean to the IPC Index

Step 13: Evaluate Trigger Activation#

../../_images/Drought_EAP_Worklow_Step_13_1.png

Purpose: The purpose of this step is to gain a quick overview of possible trigger activation without having to revise the actual data. Instead we will have a binary column with trigger = yes or trigger=no values.

Tool: Field Calculator

  1. Right-click on “IPC_index_SPI_12_district” layer -> Attribute Table-> click on Field Calculator to open the field calculator

  2. Check Create new field

  3. Output field name: Name the new column “Trigger_activation”

  4. Result field type: Text (string)

  5. Add the code below into the Expression field

Code

 
CASE

WHEN "Index_per_IPCPolygon_ML1_mean" >0.7 AND "Index_per_IPCPolygon_ML2_mean" > 0.7
AND
"SPI12_mean" < -1
THEN 'yes'
ELSE 'no'

END

  1. Click ok

  2. Save the new column by clicking on in the attribute table and end the editing mode by clicking on

Result: A layer with all districts of Somalia with a column of “Yes” and “No” values indicating whether the trigger levels have been reached or not.

../../_images/SRCS_Trigger_step_13_trigger_evaluation.png
Video: Evaluate Trigger Activation

Step 14.: Visualisation of results#

../../_images/Drought_EAP_Worklow_Step_14_1.png

Purpose: Definition of how features are represented visually on the map.

Tool: Symbology

Trigger Activation

  1. Right cklick on the “Trigger_activation” layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “Style_Trigger_Activation.qml”.

  4. Click Open. Then click on Load Style

  5. Back in the “Layer Properties” Window click Apply and OK

Info: Trigger Activation Layer

You will now see districts where no trigger is activated in green and districts with trigger activation in pink.

The “Style_Trigger_Activation.qml” style layer is configured to show the district names only where the trigger is actually activated. If there is no trigger activation you can activate the admin 1 boundary layer for better map orientation (see Administrative 2 Boundaries below)

../../_images/Map_yes_trigger.PNG

Risk Assessment

  1. Right click on the “risk_assessment_districts” layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “somalia_risk_assessment_style.qml” style layer.

  4. Move the “risk_assessment_district” layer below “Trigger_Activation” layer (Layer Concept).

  5. Back in the “Layer Properties” Window click Apply and OK

Info: Risk Assessment Layer

For the creation of an Intervention Map we will have to add the risk assessment data and the respective style file. For this first of all load from “FbF_Drought_Monitoring_Trigger/Fixed_data/Risk_Assessment” the file “risk_assessment_districts.gpkg”. This file is the output of the conducted risk assessment and contains a risk value for each district of Simaliland and Somalia. In order to visualize it

Administrative 2 Boundaries (Regions)

  1. Right click on the “Som_Admbnda_Adm1_UNDP” (Regiond) layer -> Properties -> Symbology

  2. In the down left corner click on Style -> Load Style

  3. In the new window click on the three points . Navigate to the “FbF_Drought_Monitoring_Trigger/layer_styles” folder and select the file “somalia_risk_assessment_style.qml”.

  4. Click Open. Then click on Load Style

  5. Back in the “Layer Properties” Window click Apply and OK

  6. Add a the OpenStreetMap basemap by clicking on Layer -> Add Layer -> Add XYZ layer... -> Select the OpenStreetMap. Click Add. (Wiki basemap)

  7. Place the OpenStreetMap basemap on the bottom.

  8. Delet all layers exept:

    • Trigger_activation

    • risk_assessment_districts

    • Som_Admbnda_Adm1_UNDP

    • OpenStreetMap

Video: Visualisation of results

Intervention Map without Trigger activation

Intervention Map with Trigger activation
../../_images/Map_no_trigger.PNG
../../_images/Map_yes_trigger.PNG

Attention

Remember the layer concept and make sure the basemap layer is at the bottom of your layers panel.

Step 15: Making print map#

../../_images/Drought_EAP_Worklow_Step_15_1.png

Purpose: Viualization of the map features in a printable map layout

Tool: Print Layout

  1. If not done before, delet all layers expect Trigger_activation, risk_assessment_districts and OpenStreetMap

  2. Open a new print layout by clicking on Project -> New Print Layout -> enter the name of your current Project e.g “2022_04”.

  3. Go the the FbF_Drought_Monitoring_Triggerfolder and drag and drop the fileTrigger_activation_Intervention_map.qpt` in the print layout

  4. Change the date to the current date by clicking on “Further map info…” in the items panel. Click on the Item Properties tab and scroll down. Here you can change the date in the Main Properties field.

  5. Adjust the Lgend by clicking on the legend in the Item Properties tab and scroll down until you see the Legend items field. If it is not there check if you have to open the dropdown. Make sure Auto update is not checked.

    • Remove all itemes in the legend be clicking on the item and then on the red minus icon below.

    • Add Trigger_activation and risk_assessment_districts to the legend by clicking on the green plus and click on the layer and click ok

Video: Making print map

Attention

Make sure you edit the Map Information on the template, e.g. current date. Also make sure to check the legend items: Remove unnecessary items and eventually change the names to meaning descriptions.

In order to easily visualize the output of the trigger analysis we provide you with a map template that can be used as a base for your visualization. You can find the template in the following directory: “…/FbF_Drought_Monitoring_Trigger/maps_somalia_template_risk_assessment.qpt”.

You can also adapt the template to your needs and preferences. You can find help here.

Attention

Make sure you edit the Map Information on the template, e.g. current date. Also make sure to check the legend items: Remove unnecessary items and eventually change the names to meaning descriptions.

Step 16.: Exporting Map#

../../_images/Drought_EAP_Worklow_Step_16_1.png

Purpose: Export the designed and finalized map layout in order tp print it as a pdf or format of your choice.

Tool: Print Layout

When you have finished the design of you map you can export it as pdf or image file in different datafromats.

Export as Image

  1. In the print layout click on Layer -> Export as Image

  2. Chose the Result folder in the folder you have created in step 1. Give the file the name of the project e.g 2022_04

  3. Click on Save

  4. The window “Image Export Options” will appear. Click Save Now the image can be found in the result folder in the folder you created in Step 1

Export as PDF

  1. In the print layout click on Layer -> Export as PDF

  2. Chose the Result folder in the folder you have created in step 1. Give the file the name of the project e.g 2022_04

  3. Click on Save

  4. The window “PDF Export Options” will appear. For the best results, select the lossless image compression.

  5. Click Save Now the image can be found in the result folder in the folder you created in Step 1

../../_images/map_output_example2.png