diff --git a/source/e_results_analysis_tutorial.rst b/source/e_results_analysis_tutorial.rst index 78ce1bad..896ef082 100644 --- a/source/e_results_analysis_tutorial.rst +++ b/source/e_results_analysis_tutorial.rst @@ -92,6 +92,8 @@ The first step is to create a new :ref:`schematisation`: #) Click *Create schematisation*. A popup message will tell you that the schematisation was created successfully. +.. _tut6_upload: + Uploading the schematisation ############################ @@ -123,6 +125,7 @@ We will load the schematisation in the 3Di Modeller Interface to view it. Later You should now see the DEM around Langå. +.. _tut6_run_sim: Running a simulation #################### @@ -181,6 +184,8 @@ We will now download the results of your simulation to your working directory wh The simulation results are saved in your 3Di working directory. To open this folder, click on the name of the schematisation in the 3Di Models & Simulations panel. +.. _tut6_open_sim_results: + Opening the simulation results ############################## @@ -204,7 +209,7 @@ As a first step of gaining insight in the simulation, we will check out the :ref #) Open the document *flow_summary.json*. -First, we will check if the total rainfall volume in the *flow_summary.log* matches the rainfall event (40mm in one hour). To be able to calculate this, we need to know the surface area of the model. +First, we will check if the total rainfall volume in the *flow_summary.json* matches the rainfall event (40mm in one hour). To be able to calculate this, we need to know the surface area of the model. #) In the 3Di Modeller Interface, in the Layers panel, right-click on the layer *Digital elevation model* > *Properties*. @@ -213,7 +218,7 @@ First, we will check if the total rainfall volume in the *flow_summary.log* matc .. note:: The 3Di Model in this example is atypical in that it is perfectly rectangular. All pixels in the DEM have a value. Most 3Di Models have a boundary that follows hydrogical watershed boundaries. DEM pixels outside of these boundaries are "no data" pixels. In such a case, the method used here for calculating the surface area of the model does not work. Instead, use the QGIS Processing Algorithm "Zonal statics", with an input polygon that covers the entire model domain, and choose "Count" as one of the statistics to calculate. -Secondly, you are going to volume balance the better understand de functioning of the model. +Secondly, you are going to make a volume balance to better understand the functioning of the model. #) Draw your own water balance, indicating the inflow, volume change, and outflow. Alternatively, you can use the empty balance below: @@ -221,7 +226,7 @@ Secondly, you are going to volume balance the better understand de functioning o #) Now fill in the water balance with the numbers you find in the flow summary. Check the water balance yourself; do the numbers add up? Does the difference correspond with the volume error reported in the flow summary? -The filled-in water balance can be found below: +The filled-in water balance can be found below. Note that the exact numbers may differ, as changes are sometimes made to the tutorial model. |langaa_waterbalans_antwoord| @@ -271,6 +276,12 @@ We will now make all water depths between 0 and 1 cm transparent. #) Click *OK*. +The result should look like this: + +.. image:: /image/langaa_water_depth.png + :scale: 80% + :alt: Maximum water depth map + Finding the maximum inundation depth #################################### @@ -287,13 +298,19 @@ We are going to use the Value Tool to view the inundation depth in our study are How long does the inundation last? ################################## +The maximum water depth map gives insight in *where* the flooding occurs, but does not show *when* this happens. Plotting a time series of the water level will give this insight. + #) In the 3Di Result Analysis Toolbar, click on the *Time series plotter* icon. Now the 3Di Time series plotter panel opens. #) In the 3Di Time series plotter panel, click on *Pick nodes/cells*. -#) Click on a 2D surface water node in the study area in an inundated location. A graph is plotted for the selected 2D node. +#) Click on a 2D surface water node in the inundated area near Vaethvey 21-29. A graph is plotted for the selected 2D node. Note: make sure that in the upper right drop-down menu of the 3Di Time series plotter panel, the selected variable is *Water level*. + +#) Look at the graph. When does the water level start rising? When does the peak occur and why? Why does the rate of rise decrease leading up to the peak? Is the decrease after the peak faster or slower than the increase? What does this graph tell you about the drainage situation at this location? + +.. note:: + If your subscription also includes the Scenario Archive, you can add a WMS layer of the water depth, and use the Temporal Controller to navigate through its time steps. This will give you additional insight in the progression of the flood through time. -#) Select *Water level* in the upperleft drop-down menu of the 3Di Time series plotter panel. .. _tut6_why: @@ -305,58 +322,76 @@ Now that we have established the impact and severity of the flooding, we will lo Analysing the flow pattern ########################## -Now we are going to take a first look into how the water flows through the modelled area, by visualising the flow pattern. - -First, we are going the load the results from your simulation. - -#) Click the |results_manager| *3Di Results Manager* icon. - -#) Click |add_results| *Add 3Di Grid or Results*. - -#) A pop-up screen appears where you can select the simulation results. Double-click your downloaded results. - -The results will now be added to the project. +We will start by visualising the flow pattern. Make sure you have :ref:`added the results` in the *3Di Results Manager*. -#) In the 3Di Results Manager, click the |closed_eye| icon. +#) In the *3Di Results Manager* panel, click the |closed_eye| icon. -In the layers panel, the node, flowline and cell layers have been renamed to the variable that is visualised. +In the *Layers* panel, the node, flowline and cell layers have been renamed to the variable that is visualised. -#) Toggle the *Node* and *Cell* layers to invisible. +#) Toggle the *Node* and *Cell* layers ("Water level [m MSL]") to invisible. You now see the net cumulative discharge over the whole simulation for each flowline. You may move the time slider in the *Temporal Controller* at the top of the screen to view the results for earlier moments in the simulation. In the 3Di Results Manager panel, you can also change the visualised variable to *Discharge* to get a snapshot of the situation at the time step you have navigated to in the *Temporal Controller*. +#) Zoom out from the Vaethvey a bit. Can you see the flow route(s) the water follows to flow to our problem area? By which route(s) does the water leave? + Another way to analyse the flow pattern is by using the *3Di Results Aggregation* tool. +#) Switch off the flow visualisation by clicking the *Eye* icon in the *3Di Results Manager* panel. + #) Click |resultsaggregationtoolbar| *3Di Result Aggregation* in the *3Di Results Analysis toolbar*. A pop-up screen will appear. #) In the *Input* tab, the simulation result is selected automatically. -#) Under *Preset*, select *Flow pattern*. If you are interested, you can play around with the other presets options later. Click *OK*. The flow pattern will now be derived and thre resulting layer will be added to the project. The layer shows an arrow for each calculation node. +#) Under *Preset*, select *Flow pattern*. If you are interested, you can play around with the other presets options later. Click *OK*. The flow pattern will now be derived and thre resulting layer will be added to the project. -#) You can zoom in on the flow pattern to discern the individual arrows. As you can see, the direction of the arrow indicates the direction of the flow. The colour of the arrow is scaled with the discharge. +.. note:: + The layer *Flow pattern (nodes)* shows an arrow for each calculation node; the layer *Flow pattern (nodes)_resampled_nodes* is based on the same data, but spatial interpolation has been applied to downsample the data to the resolution of the smallest calculation cell in the model. + +#) In the *Layers* panel, right-click the group *3Di Results* > *Zoom to Group*. Look at the elevation map and the flow pattern; note that the water flows from the higher areas towards the lower areas and a large part eventually ends up in the river. -#) Zoom out again to see the general flow pattern in the model area. Look at the elevation map and the flow pattern; note that the water flows from the higher areas towards the lower areas and a large part eventually ends up in the river. +The result should like like this: + +.. image:: /image/langaa_flow_pattern.png + :scale: 80% + :alt: Flow pattern + +#) You can zoom in on the flow pattern to discern the individual arrows. As you can see, the direction of the arrow indicates the direction of the flow. The colour of the arrow is scaled with the discharge. Watershed delineation for a flooded area ######################################## -To better understand why an area gets flooded and to design appropriate measures to decrease flood risks in the future, we want to know where the water in the flooded area comes from. We will use the Watershed Tool to answer this question. The Watershed Tool allows you to determine the upstream and downstream catchment at any point or area. +Another quick way to find out where the flood water comes from is using the *Watershed Tool*. The Watershed Tool allows you to determine the upstream and downstream catchment at any point or area. + +#) First, we have to make sure the maximum water depth raster is visible and the results from the previous step are hidden. In the *Layers* panel, check the layer *max_water_depth_interpolated*. In the group *3Di Results* > *{name of your 3Di Model}*, uncheck the group *Result aggregation outputs*. -#) First, we have to make sure the maximum water depth raster is still visible. In the Layers panel, check the layer *max_water_depth_interpolated*. +#) In the group *3Di Results* > *{name of your 3Di Model}* > *Computational grid*, make sure all the layers and the group itself are checked, so that the nodes are visible. #) Now, open the Watershed tool |watershed_tool| in the 3Di Results Analysis toolbar. -#) In the Watershed tool panel, define the *Input*. Select your simulations results under *3Di results*. +#) In the Watershed tool panel, define the *Input*: select your simulations results under *3Di results*. -#) Under *Settings*, you can adjust the period for which you want to carry out the watershed analysis by adjusting the start and end time. Furthermore, you can adjust the threshold. If there is a net flow from the upstream element to the target node(s) above the defined threshold, the upstream element is included in the catchment. For now, you do not need to change the settings. +#) Leave the *Settings* as they are. -#) The next step is to define the *Target nodes*. Click *Click on canvas* to activate the map tool. On the map canvas, the nodes in our study area (Vaethvey road 21-29). +#) In the section *Target nodes*, click *Click on canvas* to activate the map tool. On the map canvas, click on a node in the inundated area near Vaethvey 21-29. -The tool automatically calculates the upstream catchment area for the nodes that you selected. The result of the analysis is depicted in the figure below. By choosing *Clear results*, the catchment will disappear and you can choose different nodes to derive the upstream catchment for. +The tool automatically calculates the upstream catchment area for the nodes that you selected. By choosing *Clear results*, the catchment will disappear and you can choose different nodes to derive the upstream catchment for. #) In the *Output* section, check the *Downstream* option and uncheck the *Upstream* option. The result gives us a indication of how the flood volume is drained during and after the event. +The upstream and downstream areas for Vaethvey 21-29 should look like this: + + +.. image:: /image/langaa_watershed_output.png + :scale: 80% + :alt: Watershed tool output + +#) Using the methods outlined above, can you identify a suitable location for a flood retention basin? + +.. tip:: + Use a satellite imagery background map to help you assess the suitability of the chosen location. Click *Main Menu* > *Web* > *QuickMapServices* > *Search QMS*. In the QMS panel that opens, search for "Satellite". Choose the option you like, e.g. Google, Esri, or Bing Maps. + + .. _tut6_quant: Quantification of the flood volume @@ -364,25 +399,117 @@ Quantification of the flood volume Now that we know *where* additional storage or buffer capacity would be helpful, we need to estimate how much storage is needed, so that we can use the correct dimensions in the design of our measure. +.. _tut6_calc_flood_volume + Calculating the flood volume ############################ -Lastly, we are going to use the *Water balance tool* to determine the flood volume in our study area. +To determine the flood volume in our study area, we are going to use the *Water balance tool*. This tool calculates a water balance for each time step for a given area. We will start by creating a polygon layer that defines the area we want to make a water balance for. + +#) Click *Main Menu* > *Layer* > *Create new layer* > *New Temporary Scratch Layer*. Fill in the following values: + + - Layer name: "Flood risk area" + - Geometry type: Polygon + - CRS: EPSG:4094 - ETRS89 / DKTM2 + - You do not have to add any fields + - Click OK + +#) The new layer is added to the project in edit mode. Click |add_polygon| *Add Polygon Feature* in the main toolbar. + +#) Draw a polygon around the Vaethvey 21-29 area, stop the editing session and save your edits. The polygon should look more or less like this: + + +.. image:: /image/langaa_water_balance_polygon.png + :scale: 80% + :alt: Water balance polygon + -In the schematisation, you can see that a grid refinement was added in the area of the town that gets flooded: our study area (Vaethvey road 21-29). - #) Click the Water balance tool button |water_balance_tool| in the 3Di Results Analysis toolbar. -#) Choose *Select polygon* and click the grid refinement area. Choose *grid refinement area (study_area)* in the popup menu. The tool will now automatically calculate and visualize the water balance for this area. - -.. note:: - You can use any polygon layer as water balance area. If you do not yet have a polygon for your area of interest, create one first. In the main toolbar, click |new_geopackage|, or go to *Main Menu* > *Layer* > *Create new layer* > *New Geopackage Layer*. +#) Choose *Select polygon* and click on the polygon. Choose *Flood prone area* in the context menu. The tool will now automatically calculate and visualize the water balance for this area. #) In the water balance plot, you can either show discharge (m³/s) or volumes (cumulative discharge, m³). The tool is automatically set to discharge. Now change to volume by using the dropdown menu and choose the *m³ cumulative* option. #) In the graph, the cumulative volumes of water for flows are displayed. At the right side, you can activate and deactivate different the flows. Hover over the different components to see which ones are indicated in the graph. -#) The main component that is of interest in this question is *2D flow*. Notice that the graph displays both a positive and negative cumulative 2D Flow. This is caused by the fact that the 2D flow is both entering (positive) and leaving (negative) the study area. The net 2D flow (change in storage) is represented by the dotted red line, representing the *volume change 2D*. Use your mouse to zoom in on the y-axis. You can check the net 2D volume change at the end of the simulation. Check that the flow volume is about 3,200 m³. +The main component that is of interest in this question is *2D flow*. Notice that the graph displays both a positive and negative cumulative 2D Flow. The positive 2D flow indicates flow into the polygon, the negative 2D flow indicates flow out of the polygon. The net 2D flow (change in storage) is represented by the dotted red line, representing the *volume change 2D*. Use your mouse to zoom in on the y-axis. You can check the net 2D volume change at the end of the simulation, which should be around 2000 m³. + +#) What is the total (gross) inflow into the polygon? + +.. _tut6_apply_measures: + +Applying measures +------------------ + +The last step is to include the new retention area in the model, to see if it works as intended. Based on our analysis and the suitability of the terrain, the following location is chosen as retention area: + +.. image:: /image/langaa_retention_area.png + :scale: 80% + :alt: Retention area location + +Drawing the retention area polygon +################################## + +#) Create a new scratch layer, in the same way as you did in :ref:`tut6_calc_flood_volume`. Name it "Retention area". + +#) Draw the new retention area on the map. + +#) Make sure the layer "Retention area" is selected in the *Layers* panel. + +#) Click *Main Menu* > *View* > *Panels* > *Layer styling* to open the Layer Styling panel. + +#) In the *Layer Styling* panel, go to the *Labels* tab and set it to *Single labels* + +#) In the *Value* input, type ``round($area)``. Now click anywhere outside that input field. The Retention area polygon should now be labelled with its surface area (in square meters). + +#) In the sub-tab *Buffer*, check the box *Draw text buffer* to make the label easier to read. + +#) How deep must the retention area be so that it can contain all the water that flows into the flood prone area at Vaethvey 21-29? + +#) Use the |value_tool| *Value Tool* to find out what the current elevation is within the new retention area. What should be the new elevation of the bottom of the retention area? + + +Editing the DEM +############### + +We will now use this polygon to edit the DEM, so that we can assess the effect of the new retention area. + +#) Open the *Processing Toolbox* (*Main Menu* > *Processing* > *Toolbox*). + +#) In the search bar, type "Rasterize" + +#) Open the Processing Algorithm "GDAL > Vector Conversion > Rasterize (overwrite with fixed value)" + +#) Fill in the following parameters: + + - Input vector layer: "Retention area" + - Input raster layer: "Digital Elevation Model [m MSL]" + - A fixed value to burn: fill in the new elevation that you have calculated in the previous step + +#) Click OK and wait for the processing algorithm to finish. + +#) When the processing algorithm is finished, use the *Value Tool* to check if the new value has been burned into the DEM correctly. + +Running a simulation with the edited DEM +######################################## + +You can now repeat the steps you have done earlier in this tutorial to check if the measure has been effective. + +- :ref:`tut6_upload` + +- :ref:`tut6_run_sim` + +- :ref:`tut6_impact` + +Has this measure solved the whole flood problem for Vaethvey 21-29? If not, what additional measures can be taken? + +Congratulations +############### + +Well done! You have finished the tutorial Analysing simulation results! + +If you would like to learn more about the tools available for analysing your 3Di simulation results, check out the :ref:`mi_analysing_results` section of the 3Di Modeller Interface User Manual. + .. |langaa_waterbalans_leeg| image:: /image/langaa_waterbalans_leeg.png :scale: 100% @@ -396,6 +523,9 @@ In the schematisation, you can see that a grid refinement was added in the area .. |toggle_editing| image:: /image/pictogram_toggle_editing.png :scale: 80% +.. |add_polygon| image:: /image/pictogram_addpolygon.png + :scale: 80% + .. |add_line| image:: /image/pictogram_addline.png :scale: 80% @@ -443,6 +573,3 @@ In the schematisation, you can see that a grid refinement was added in the area .. |new_geopackage| image:: image/new_geopackage.png :scale: 100% - -.. check zipje!! (nieuw zipje kan reinout of wolf online zetten voor je) - diff --git a/source/image/langaa_flow_pattern.png b/source/image/langaa_flow_pattern.png new file mode 100644 index 00000000..9d42d131 Binary files /dev/null and b/source/image/langaa_flow_pattern.png differ diff --git a/source/image/langaa_retention_area.png b/source/image/langaa_retention_area.png new file mode 100644 index 00000000..cb8cbb01 Binary files /dev/null and b/source/image/langaa_retention_area.png differ diff --git a/source/image/langaa_water_balance_polygon.png b/source/image/langaa_water_balance_polygon.png new file mode 100644 index 00000000..0ce9d240 Binary files /dev/null and b/source/image/langaa_water_balance_polygon.png differ diff --git a/source/image/langaa_water_depth.png b/source/image/langaa_water_depth.png new file mode 100644 index 00000000..a1b1b61a Binary files /dev/null and b/source/image/langaa_water_depth.png differ diff --git a/source/image/langaa_watershed_output.png b/source/image/langaa_watershed_output.png new file mode 100644 index 00000000..44826f60 Binary files /dev/null and b/source/image/langaa_watershed_output.png differ