::::{grid} auto :::{grid-item-card} :class-card: sd-text-center sd-rounded-circle :link: https://giscience.github.io/gis-training-resource-center/english/content/en/intro.html {octicon}`home-fill;1.5em;sd-text-danger` ::: :::: # Exercise 4: Visualizing Cyclone Impact Results – Aina Styles Her Layers ## Characteristics of the exercise ::::{grid} 2 :::{grid-item-card} __Type of trainings exercise:__ ^^^ - This exercise can be used in online and presence training. - It can be done as a follow-along exercise or individually as a self-study. ::: :::{grid-item-card} __Exercise Track:__ This exercise is part of the [Madagascar Anticipatory Action Cyclon Analysis Exercise Track](https://giscience.github.io/gis-training-resource-center/english/content/en/Exercise_tracks/en_mdg_aa_cyclones.html). ::: :::: ::::{grid} 2 :::{grid-item-card} __Estimated time demand for the exercise__ ^^^ ::: :::{grid-item-card} __Relevant Wiki Articles__ ^^^ * [Zonal Statistics](https://giscience.github.io/gis-training-resource-center/english/content/en/Wiki/en_qgis_raster_basic_wiki.html) * [Intersection](https://giscience.github.io/gis-training-resource-center/english/content/en/Wiki/en_qgis_spatial_joins_wiki.html#join-attributes-by-location-summary) * [Projections](../Wiki/en_qgis_projections_wiki.md) * [Buffer](../Wiki/en_qgis_projections_wiki.md) * [Clip](../Wiki/en_qgis_projections_wiki.md) * [Automatisation](https://giscience.github.io/gis-training-resource-center/english/content/en/Wiki/en_qgis_automatisation_wiki.html) ::: :::: :::{card} :class-card: sd-border-1 sd-shadow-none __Aim of the exercise:__ ^^^ Aina, the GIS expert at the Malagasy Red Cross (CRM), is preparing for the upcoming cyclone season. She wants to improve her team’s ability to act quickly once a storm is forecasted by automating key analyses in QGIS. These include estimating exposed populations, identifying impacted services like health and education, and assessing whether health posts can be reached from key warehouses within a critical 10-hour window. The goal is to prepare an end-to-end analysis and visualization workflow that can support fast, data-driven anticipatory action before a cyclone makes landfall. ::: ## Instructions for the trainers :::{dropdown} __Trainers Corner__ ### Prepare the training - Take the time to familiarise yourself with the exercise and the provided material. - Prepare a white-board. It can be either a physical whiteboard, a flip-chart, or a digital whiteboard (e.g. Miro board) where the participants can add their findings and questions. - Before starting the exercise, make sure everybody has installed QGIS and has downloaded __and unzipped__ the data folder. - Check out [How to do trainings?](https://giscience.github.io/gis-training-resource-center/english/content/en/Trainers_corner/en_how_to_training.html#how-to-do-trainings) for some general tips on conducting trainings. ### Conduct the training __Introduction:__ - Introduce the idea and aim of the exercise. - Provide the download link and make sure everybody has unzipped the folder before beginning the tasks. __Follow-along:__ - Show and explain each step yourself at least twice and slow enough so everybody can see what you are doing, and follow along in their own QGIS-project. - Make sure that everybody is following along and doing the steps themselves by periodically asking if anybody needs help or if everybody is still following. - Be open and patient to every question or problem that might come up. Your participants are essentially multitasking by paying attention to your instructions and orienting themselves in their own QGIS-project. __Wrap up:__ - Leave time for any issues or questions concerning the tasks at the end of the exercise. - Leave some time for open questions. ::: ## Available data :::{card} :link: https://nexus.heigit.org/repository/gis-training-resource-center/GIS_AA/MDG/Module_4_Exercise_6_AA_MDG_task_4-20250825T143508Z-1-001.zip __Download all datasets here, save the folder on your computer and unzip the file.__ ::: ## Context Aina now has all the analysis results she needs — but numbers and tables alone won’t convince her colleagues or decision-makers. What they need are clear and easy-to-read maps that can be used directly in meetings and reports. To save time, Aina doesn’t want to adjust colors and legends manually each time a new cyclone comes in. Instead, she will use ready-made style files (.qml) that instantly give layers a professional and consistent look. Where no style exists yet, she will create one herself, so that next time the map can be updated with just a few clicks. In this task, you will help Aina make her cyclone impact maps both informative and visually compelling by applying and creating QGIS style files. ## Tasks ### 1. **Load Required Layers (if not already loaded)** Make sure the following layers are already loaded into your QGIS project. These are outputs from **Task 3**: - `example_Harald_2025_Track` - `cyclone_harald_buffer` - `Harald_Exposed_Population` - `admin2_health_affected` - `admin2_education_affected` If any are missing: - Load them using **drag & drop** from your `results` folder, or - Use `Layer` → `Add Layer` → `Add Vector Layer` or `Add Raster Layer`. --- ### 2. **Apply Predefined Style Files** Apply the following`.qml` style files to the respective layers: | **Layer** | **Style File** | |-----------------------------|------------------------------------------| | `example_Harald_2025_Track` | `storm_track_cyclone_style.qml` | | `cyclone_harald_buffer` | `exposed_cyclone_area_style.qml` | | `Harald_Exposed_Population` | `exposed_population_style.qml` | | `admin2_health_affected` | `exposed_healthsites_style.qml` | | `admin2_education_affected` | `exposed_education_facilities_style.qml` | :::{note} ⚠️ For the **health** and **education facilities**, the provided style files are linked to the column containing the **sum of exposed facilities**. They are **not** based on the percentage column. ::: **Steps:** - Right-click on the layer in the **Layers Panel**. - Select `Properties`. - In the window that opens, go to the `Symbology` tab. - At the bottom left, click `Style` → `Load Style…`. - Click on the three points ![](../../../fig/Three_points.png). - Navigate to the corresponding `.qml` file in the folder `layer_sytle` and select it. - Click `Open`, then `Apply` and `OK` to confirm. > 💡 *If the style doesn’t load correctly, double-check the column names and make sure the column name used in the `.qml` file matches the one in your layer. To do this, open the **Attribute Table** of the layer and compare field names.* --- :::::{tab-set} ::::{tab-item} Intermediate result: Exposed Population :::{figure} ../../../fig/fr_MDG_AA_intermediate_result_model_task4_exposed_pop_style.PNG --- width: 600px align: center --- Map showing the numberof persons exposed per district using the .qml style file. ::: :::: ::::{tab-item} Intermediate result: Exposed Health Facilities :::{figure} ../../../fig/fr_MDG_AA_intermediate_result_model_task4_exposed_HS_sum_style.PNG --- width: 600px align: center --- Map showing the exposed health establishments per district. ::: :::: ::::{tab-item} Intermediate result: Exposed Education Facilities :::{figure} ../../../fig/fr_MDG_AA_intermediate_result_model_task4_exposed_ES_sum_style.PNG --- width: 600px align: center --- Map showing the number of education institutions exposed per district. ::: :::: ::::: ### 3. **Style Percentage Layers Manually** Aina also wants to visualise the percentage of exposed health and education facilities. However, since there is no prepared style available, she must complete the process manually. **Steps:** - Right-click on the layer `admin2_health_affected` → select **Duplicate Layer** - **Rename** the duplicated layer to: ``` admin2_health_affected_percentage ``` - Right-click on the layer in the **Layers Panel** - Select **Properties** - In the window that opens, go to the **Symbology** tab - Set **Symbology** to `Graduated` - Choose the correct **field**: - `pct_health_affected` - Open the **Histogram** tab to view the value distribution by clicking on `calculate histogram` - Next go back to `Classes` and set the following configuration: - **Mode**: `Equal Interval` - **Classes**: `4` - Click `OK`.This will create four classes (`0–25%`, `25–50%`, `50–75%`, `75–100%`) - Choose a color ramp (e.g., light yellow → dark red) - Optionally customize class labels for clarity - Click `Apply` - Repeat the same process for the layer `admin2_education_affected`. After duplicating the layer, rename the new one to: ``` admin2_health_affected_percentage ``` > 🧠 *Why 4 equal classes?* > This helps visualize severity across districts using simple and interpretable risk categories. However, you can experiment with **Natural Breaks** if data is unevenly distributed. --- ### 4. **Save Your New Styles for Reuse** Save your manually created styles as `.qml` files for future reuse. **Steps:** - Right-click on the layer in the **Layers Panel** - Select **Properties** - In the window that opens, go to the **Symbology** tab - Click on `Style` → `Save Style…` - Save the file in the folder `layer_style` - Use these filenames: ``` health_pct_affected_style ``` ``` education_pct_affected_style ``` ### 5. *(Optional)* Import Styles into Your QGIS Library To reuse your styles in any future project: - Go to `Settings` → `Style Manager`. - Click `Import/Export` → `Import Items`. - Browse to and select your saved `.qml` files. The styles will now appear as presets in the **Layer Styling Panel**. ---