RISKSCAPE TUTORIAL 4: 200 YEAR ANNUAL RETURN INTERVAL (ARI) HEATHCOTE RIVER FLOOD EVENT: MITIGATING IMPACTS ON CHRISTCHURCH BUILDINGS Welcome to the RiskScape tutorial: 200 Year ARI Heathcote River Flood Event: Mitigating Impacts on Christchurch Buildings? For this exercise we will use a scenario developed for the Christchurch City Council; the impact of inundation on assets from a 200 year Annual Recurrence Interval (ARI) flood event. From this scenario we will produce datasets using both RiskScape and the RiskScape Asset Modification tool to investigate the reduction of flood impacts and costs for buildings by raising their floor levels. It is assumed that you are already familiar with RiskScape s Graphical User Interface (GUI), Model Run Sequence and Data Aggregation options. If not, then it is advised that you first complete the RiskScape introduction tutorials at https://wiki-riskscape.niwa.co.nz/index.php/tutorials. These cover all the basic steps required to run an impact or risk model then view and export the results. Step 1: Load RiskScape Using the programs menu find and start RiskScape. RiskScape is loading when you see the opposite image appear on your screen. Step 2: Run a model for building and human impacts Once RiskScape has loaded, maximise the screen size. In the three decision boxes choose the assets, hazard and impacts for the model run. For this exercise select Canterbury Buildings (Assets), Flood (Hazards) and Damage State and Reinstatement Costs (Impacts). You will see that all Impacts are available however, for this analysis we will only select Damage State and Reinstatement Cost. Add selections to Library.
Step 3: Choose a building dataset The first model refinement decision will be to choose a building dataset. As impacts to all Christchurch buildings is of interest we will select the Use complete dataset option. If you were interested in modelling the impacts to a subset of Christchurch buildings (e.g. timber buildings) you can choose the Use subset option and use the entire Christchurch building dataset for use in the model run. Select Use complete dataset and click Next. Step 4: Choose an aggregation unit As RiskScape is a regional impact and risk modelling tool, the final model run results are aggregated to an area unit (e.g. grid (1km x 1km), meshblock or suburb) rather than a per site or asset basis. While RiskScape models impacts on a per asset basis, aggregating impact data to larger area units helps to reduce some uncertainties associated with modelling impacts for individual assets. Choose the Suburbs NZMG aggregation option to aggregate data for the model run and click Next. Step 5: Choose a flood model One or a number of hazard models could be available for an asset type in the area of interest. In this case, Christchurch has flood inundation models for different climate change scenarios, Heathcote River 100 and 200 year Annual Return Interval (ARI) flood events pre- and post- 2011 Christchurch earthquake. For this model run we will model a pre- 2011 Christchurch earthquake Heathcote River 200 year ARI flood event so select Christchurch Heathcote Flood. Click Next to continue. Step 6: Choose Hazard Parameters For each hazard model option there may be a number of models available. For the Christchurch Heathcote Flood module there are flood inundation models for 100 and 200 year ARI flood events. Select the 200 year ARI flood event and click Next to continue.
Step 7: Choose Impact Model(s) Flood impacts to buildings can be determined in RiskScape from a vulnerability model that uses a relationship between building impacts and either a flood-depth and velocity or flood-depth. While flood flow velocity can have an important influence on the levels of building damage experienced, we will use the Depth Only vulnerability model for both impacts. Select depth only and click Next to continue. Step 8: Choose time of impact occurrence Time of occurrence can be an important influence on flood damage to buildings and their contents as people present can take precautions to reduce damage e.g. storing possessions above flood water levels. Building occupancy reduces during daytime as people leave for work, school etc. Select Daytime for the model run to maximise the potential building and contents impacts for the 200 year ARI event and click Next to continue. Step 9: Choose a mitigation factor Similar to Step 8, none or a short warning prior to flooding will potentially result in greater building and content damage from an event as people have less time to take precautions that reduce damage. To further maximise the potential building contents loss for the 200 year ARI event select No flood warning and short lead time. Click Next, name the model run and click Finish continue. Step 10: Add model run to library and run analysis Find your model run in the Library and click on the Play button to perform the analysis. It might take a minute has the impacts for the run are being calculated. You will notice that some icons are greyed. These cannot be used during the analysis but will appear when the analysis is completed and will be used to export the model run results in Step 11.
Step 11: Export aggregated model results Building reinstatement cost results aggregated for Christchurch Suburb unit areas can be viewed or exported by clicking the RiskScape logo/magnify glass icon. For this step we will choose to aggregate Reinstatement Costs from the model run then export the aggregated Asset Repair cost results a csv file following the selection process from 1 to 4 (see opposite). 1 2 Click Finish after 4 (see opposite) to open the results in a csv file. Sum the aggregated suburb results for each column to calculate the total reinstatement costs for the event. 3 4 Repeat Step 11 to calculate the building Damage State results. We will now use the Asset Mitigation Tool to raise floor levels for all buildings in the Christchurch Buildings dataset and compare the differences in building reinstatement costs and damage state results. Step 12: Start Asset Mitigation Tool Access the RiskScape Asset Mitigation Tool by minimising RiskScape, then on the desktop clicking Start and All programs. Open the RiskScape folder and select RiskScape Tools. This will open the RiskScape Tools window where you will see the Asset Modification Tool symbol to the bottom right. Click the symbol to open the Asset Mitigation Tool page. Step 13: Import Christchurch Buildings When the Asset Modification Tool page is open you will need to navigate through the panels on the left. First we need to select browse to find the RiskScape module with Canterbury buildings. The file selector will start in the RiskScape modules directory, so all you need to do is choose the canterbury-buildingsnzmg.rksa file then click on Open to import Canterbury buildings into the Asset Modification Tool. Click on Continue to choose to modify the Christchurch building attributes.
Step 14: Filter Building Attributes We now need to filter the types of building attributes available in order to assess the consequences of raising the height of floor levels. To do this we need to make some asset attribute decisions. A define filter box will pop up on the left and a box with a question mark will appear in the middle of the screen. To filter asset attributes so that we are only to assess flood impact reduction from raising floor level heights, find Floor Height in the Attribute Decisions box in the top right of the screen, then click and drag Floor Height into the box with the question mark. A decision tree now appears that allows us to make decisions on how to modify floor level heights in the Canterbury building module. Step 15: Filter building floor heights and types to be raised For this scenario we will raise the floor levels of all timber floor buildings to at least 1m above ground level. Firstly, in large grey shaded box, type 1 in the bottom left box with the white background. This means that all buildings in Canterbury with floor heights below 1m will be selected. Now we need to select the floor types to raise up to this floor height. In the Attribute Decisions box to the top right of the screen, select and drag the Floor Type attribute into the bottom left box with the question mark. The box will split and two attributes for Timber and Concrete Slab will appear on the left. Drag Concrete Slab over to the right side. This step allows us to decide how we would like to run an analysis on floor levels for each floor type. In the box at the bottom right of the screen titled Other, select and drag Dead End into the box below Concrete slab and right-hand box under floor height as we will not be making decisions on these attributes. Now select and drag New Modification into the question mark box located beneath the split box titled Floor Type (on the lower left). This now enables us to make decisions on how we will modify timber floors for our analysis i.e. raise all or a proportion of floors up to 1m.
Step 16: Set Floor Level Height A page will now pop up requiring the modification to the building floor type to be created. In the grey box titled Creating a modification, select Floor Height in the drop down box and click OK. In the box titled Floor Height select Adjust values by. Type 100 under Proportion%, 1 under Mean and 0 under Std.Deviation then click Add. These modifications are no set to be applied which will mean all timber floors within the Canterbury building dataset will be raised by 1m above their current height. Click OK and then on the main page click Continue. Feel free to save the filtering process you created when prompted in case you need to revisit it. Review the decision tree and click on continue in the panel on the left titled Review Changes to proceed. Step 17: Define Metadata Now we need to define the Metadata for the asset mitigation scenario. The metadata provides brief information about the Canterbury building module data such as the data type, where it was source and any modifications made. In Define Metadata, change the Module Name e.g. Canterbury Buildings 1m Floor Level. Every RiskScape model and dataset must supply a readme file so that users of the model/dataset know what it is that they are looking at. As we are modifying the Christchurch buildings dataset, there is already some information from the original dataset, but we must add a note to indicate what we have done. In the module description box, type in a description of the changes you have made. If you want to enter more than one line of information, click on the expand icon and then type into the larger box that pops up. Once you have entered your comments, click Continue to proceed (Note: all fields must have text). Step 18: Save Outputs In the Output settings panel, click the box next to Save Module and the click browse. This should direct you into the modules folder where asset modules are stored for RiskScape to access. You will see that the Canterbury-buildings-nzmg.rksa file is already showing in the file name window. We don t want to overwrite our original dataset so edit the file name to something like Canterbury-buildings-timberfloorsraised.rksa the select save and continue. Saving the module takes about a minute so have a stretch.
Step 19: Run an analysis for the modified Canterbury Building dataset and compare results You have now created a module to investigate the reduction in costs to buildings from a Christchurch 200 year ARI flood event by raising all timber floor levels by at least 1m above ground level. Now let s plug the module we have just created in the Asset Modification Tool into RiskScape and run a new analysis. The analysis we run will be saved in the library and available for comparison. Restart RiskScape (close and restart if open) and find your new modified asset dataset in the view the Assets box on the GUI. Using the new modified asset dataset, now run a new analysis by repeating Steps 2 to 11. Export results as a csv file and see whether raising all timber floors by 1m has reduce the overall reinstatement costs and damage states of Christchurch buildings for a 200 year ARI Heathcote River flood event. If you re really keen create another asset modification and raise these floor heights by 1.5m to see if there is a further reduction in overall reinstatement costs and damage states. YOU HAVE NOW COMPLETED THE TUTORIAL. YOU MAY WANT TO TRY OTHER RISKSCAPE TUTORIALS AT https://wiki-riskscape.niwa.co.nz/index.php/tutorials AND TEST RISKSCAPE FOR OTHER NATURAL HAZARDS AND IMPACTS. THANK YOU. PLEASE NOTE: THIS TUTORIAL IS FOR DEMONSTRATION PURPOSES ONLY AND THE RESULTS PRODUCED ARE NOT INTENDED TO INFORM NATURAL HAZARD MANAGEMENT DECISION MAKING. PLEASE CONTACT RISKSCAPE AT info@riskscape.org.nz IF YOU WOULD LIKE TO FIND OUT MORE ABOUT USING RISKSCAPE FOR NATURAL HAZARD MANAGEMENT ACTIVITIES.