Loss Calculation and Scenario Module
=====================================

This section explains how to calculate **Loss** using previously calculated exposure data, and how to create and apply different **Scenarios** (e.g., future hazard models or urban development changes) in RiskChanges.

Before proceeding, ensure that all necessary data (Hazard, Elements-at-Risk, Vulnerability) has already been uploaded, and Exposure layers have been calculated. Please refer to the :ref:`Input Data and Exposure <calculate-exposure>` section if needed.

Calculate Loss
^^^^^^^^^^^^^^^^^

The Loss module computes the **economic or physical losses** resulting from hazard exposure and vulnerability. Loss is calculated as a function of:

- Hazard intensity (from the Exposure layer)
- Vulnerability curve
- Value of the exposed elements

.. figure:: /images/tutorials_lossandscenario/losscalculation.png
   :scale: 60%
   :align: center

   *Loss calculation settings*

**Steps to Calculate Loss:**

1. **Open the Loss Module**

   - Go to the **Project Page**.
   - Click on the **Loss** tab in the sidebar.
   - Click **Add Loss**.

2. **Choose Calculation Type**

   As in the Exposure module, you can choose:
   - **Individual**: Calculate loss per feature.
   - **Aggregated**: Calculate loss based on administrative units.

3. **Fill in General Details**

   - Enter a **Layer Name**.
   - Select the **Exposure Layer** you want to use for the loss calculation.
   - Click **Save & Next**.

4. **Link to Vulnerability Curves**

   A table will appear showing the **classes of Elements-at-Risk** (e.g., building types).
   
   For each class:

   - Choose an appropriate **Vulnerability Curve** from the dropdown list.
   - You can select from **All Vulnerability** (public records) or **My Vulnerability** (project-specific).

   After assigning all classes, click **Save**.

1. **View Results**

   Once calculated:
   
   - A **Loss Layer** will be displayed on the map.
   - The results table will show extended details, including:
     - Damage Ratio
     - Loss Fraction
     - Loss Area or Length
     - Loss Number of Floors

.. figure:: /images/tutorials_lossandscenario/resulttable.png
   :scale: 60%
   :align: center

   *Loss calculation result table*

Similarly, results summary and chart are also provided in RiskChanges.

.. figure:: /images/tutorials_lossandscenario/summarychart.png
   :scale: 60%
   :align: center

   *Loss result summary and chart*

6. **Adjust Map Visualization**

   - Use the **Style** section to customize the appearance of the Loss Layer.
   - Users can set classification methods, color ramps, and labels to enhance interpretation.

.. figure:: /images/tutorials_lossandscenario/mapvis.png
   :scale: 60%
   :align: center

   *Loss result visualized in a map*

Create Scenario
^^^^^^^^^^^^^^^^^^

The **Scenario Module** in RiskChanges allows you to simulate future changes that affect risk levels—such as:
- **Climate change**
- **Population growth**
- **Land-use changes**

Scenarios are used to model **how risk evolves over time**.

**Steps to Create a Scenario:**

1. **Open Project Settings**
   - Go to the **Project Dashboard**.
   - Select your project and click **Settings** (gear icon).

2. **Add a New Scenario**
   - Go to the **Scenarios** tab.
   - Click **Add Scenario**.

.. figure:: /images/tutorials_lossandscenario/newscenario.png
   :scale: 60%
   :align: center

   *Create a scenario*

3. **Fill Scenario Details**
   - **Scenario Name**: Provide a meaningful name (e.g., "2050 Climate Change").
   - **Risk Component Affected**: Select which component changes (Hazard, EaR, Vulnerability).
   - **Description** (optional): Brief explanation of the scenario.
   - **Upload File(s)**: Attach supporting documents (if any).

.. figure:: /images/tutorials_lossandscenario/scenariodetails.png
   :scale: 60%
   :align: center

   *Fill scenario details*

4. **Save the Scenario**
   - The scenario will appear in the **Scenario Table**.
   - When uploading hazard or EaR layers, you can now assign this scenario to them.

Calculate Loss for Different Scenarios
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Once a scenario is created, you can calculate Exposure and Loss under that scenario by uploading the appropriate **Hazard** or **EaR** datasets marked with the scenario name.

Repeat the steps from:
- :ref:`Calculate Exposure <calculate-exposure>` for exposure calculation
- :ref:`Loss Calculation <loss-calculation>` (this section) for loss calculation

.. figure:: /images/tutorials_lossandscenario/applyscenario.png
   :scale: 60%
   :align: center

   *Applying scenario into calculation*

**Important:**  
When uploading data or calculating exposure/loss under a scenario, make sure to **select the correct Scenario Name** in the data form. This ensures the results are correctly associated.