Using my own wave data - Coastal Vulnerability Model

Hi!

I'm working on some scenarios of coastal modelling and would like to use my own wave data in the Coastal Vulnerability Model.

The user's guide isn't very clear on how I should do this, but it does say that "these data must be contained in a point shapefile with the same attribute table as the WW3 data provided" and Appendix B gives instructions on wind data.

Am I missing something? 


cheers,
Carla


Comments

  • Hi Carla,

    I think the best thing to do would be to take a look at the sample data included with InVEST (CoastalProtection --> Inputs --> WaveWatchIII) and read over the instructions in Appendix B (copied below) to get a sense of how the data should be formatted.  You will need to compute some statistics from your data, and there's specific formatting of the attribute table (see the description of columns below).  You will want your data formatted the same way as the WWIII data is, so that should be a good guide.  You can also always get the model up and running using the default WWIII data included with the model as you work on formatting your own data.

    J.

    Wind data

    To estimate the importance of wind exposure and wind-generated waves, wind statistics measured in the vicinity of the AOI are required. From at least 5 years of data, the model requires the average in each of the 16 equiangular sectors (0deg, 22.5deg, etc.) of the wind speeds in the 90th percentile or greater observed near the segment of interest to compute the REI. In other words, for computation of the REI, sort wind speed time series in descending order, and take the highest 10% values, and associated direction. Sort this sub-series by direction: all wind speeds that have a direction centered around each of the 16 equiangular sectors are assigned to that sector. Then take the average of the wind speeds in each sector. If there is no record of time series in a particular sector because only weak winds blow from that direction, then average wind speed in that sector is assigned a value of zero (0). Please note that, in the model, wind direction is the direction winds are blowing FROM, and not TOWARDS.

    For the computation of wave power from wind and fetch characteristics, the model requires the average of the wind speeds greater than or equal to the 90th percentile observed in each of the 16 equiangular sectors (0deg, 22.5deg, etc.). In other words, for computation of wave power from fetch and wind, sort the time series of observed wind speed by direction: all wind speeds that have a direction centered on each of the 16 equiangular sectors are assigned to that sector. Then, for each sector, take the average of the highest 10% observed values. Again, please note that, in our model, wind direction is the direction winds are blowing FROM, and not TOWARDS.

    If users would like to provide their own wind and wave statistics, instead of relying on WW3 data, the must enter the data in the following order:

    1. Column 1-2: Placeholder. No information required.
    2. Columns 3-4: LAT, LONG values. These values indicate the latitude and longitude of the grid points that will be used to assign wind and wave information to the different shoreline segments.
    3. Columns 5-20: REI_VX, where X=[0,22,45,67,90,112,135,157,180,202,225,247,270,292,315,337] (e.g., REI_V0). These wind speed values are computed to estimate the REI of each shoreline segment. These values are the average of the highest 10% wind speeds that were allocated to the 16 equiangular sectors centered on the angles listed above.
    4. Columns 21 to 36: REI_PCTX, where X has the same values as listed above. These 16 percent values (which sum to 1 when added together) correspond to the proportion of the highest 10% wind speeds which are centered on the main sector direction X listed above.
    5. Column 37 to 52: WavP_X, where X has the same values as listed above. These variables are used to estimate wave exposure for sites that are directly exposed to the open ocean. They were computed from WW3 data by first estimating the wave power for all waves in the record, then splitting these wave power values into the 16 fetch sectors defined earlier. For each sector, we then computed WavP by taking the average of the top 10% values (see Section The Model).
    6. Column 53 to 68: WavPPCTX, where X has the same values as listed above. These variables are used in combination with WavP_X to estimate wave exposure for sites that are directly exposed to the open ocean. They correspond to the proportion of the highest 10% wave power values which are centered on the main sector direction X (see Section The Model).
    7. Columns 69 to 84: V10PCT_X, where X has the same values as listed above. These variables are used to estimate wave power from fetch. They correspond to the average of the highest 10% wind speeds that are centered on the main sector direction X.

    If users decide to create a similar layer, it is recommend that they create it in Microsoft Excel, and add the sheet in the “Layer” menu. To plot the data, right-click on the sheet name, and choose “Display XY Data”. Choose to display the X and Y fields as “LONG” and “LAT”, respectively. If users are satisfied with the result, right-click on the layer, choose “Export Data” and convert this temporary “Events Layer” into a point shapefile that can now be called when running the Coastal Vulnerability model. Finally, we recommend to use a WGS84 datum.

    As described in The Model section cv-winds, the model provides an optional map of areas that are exposed or sheltered. This is purely based on fetch distances, and does not take into account measurements of wind speeds. To prepare this map, the model uses an estimate of a fetch distance cutoff to use that the user has defined, based on the AOI under consideration. To provide that distance, it is recommend that the “distance tool” on the global polygon layer, zoomed into the AOI, is used to determine that distance.

  • Hi Carla,

    I don't know if the data you have is raw data from a buoy or already processed data. In the former case, as Jess mentions, you may need to do some not-so-trivial statistical manipulation. Instructions in the user guide and in general literature should be enough, but if you get lost at some point, feel free to contact me at sergiomv@stanford.edu. 

    Cheers,

    Sergio
  • Thanks, Jess and Sergio!

    My data comes from an already processed database (phew!). I've used the Coastal Vulnerability model in my MSc thesis, but I had to create a huge AOI because of the amount of WWIII points available in the area.

    For my PhD I'm looking into climate change impacts, so I'll be modelling wave climate on a separate software and thought of using the results as an input for InVEST.

    I'll study the WWIII attribute table and talk to the developers of the coastal modelling system I'm using to see what can be done!

    cheers,
    Carla

    *P.S.: If anyone's interested, here's the link to the article from my MSc thesis: http://www.sciencedirect.com/science/article/pii/S0964569116303258
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