Analysing Spatial Rainfall with TVD connectors

InfoWorks ICM version 8.0 was released with several new features. One new feature is the “Averaged Spatial Rainfall on TVD connectors” and this post is an example of the flexibility that it offers you.

What is it for?
Have you wonder what is the rainfall over an area? This can simply be answered with the “Averaged Spatial Rainfall on TVD connectors” feature.
The increasing resolution of spatial rainfall from radar data, with spatial resolutions as detailed as 50 metres, means the number of radar cells over an area can be significant and instead of analysing each cell you might want to analyse the average rainfall intensity over an area. This new feature enables you to calculate the Averaged Spatial Rainfall on a TVD connector polygon, which can then be used to plot rainfall averages and also to trigger alerts in a live system with InfoWorks ICMLive.

How it works?
This feature is based on the definition of TVD polygons with the output units “R – rainfall intensity (mm/hr)” in a model network, as exemplified in Figure 1. These TVD polygons need to cover an area with available radar data, but they do not need to cover network objects (apart from spatial rain zones if defined).

Figure 1. Example of a TVD connector to analyse the averaged spatial rainfall.

The model network can then be used in a run to make the spatial rainfall analysis on the TVD connector polygon. Figure 2 shows an example of the Averaged Spatial Rainfall on a TVD polygon. The results shows the average rainfall calculated for the observed and forecast periods that were based on different radar sources, and the comparison with the rainfall over one radar cell only. The rainfall on TVD connectors calculates the area-average of the rainfall from all radar cells that overlap the TVD polygon. Therefore, this feature enables the analysis of averaged rainfall of all the rain sources within the polygon, which can be similar but have slight differences to the rainfall on one radar cell only. In addition, it offers advantage of aggregating data from various sources, such as observed and forecasting radar data.

Figure 2. Example of the “Averaged Spatial Rainfall” (left graph) and the rainfall data from one radar cell only inside the polygon (right graph).

So, this is another flexible feature!

In conclusion, the feature “Averaged Spatial Rainfall on TVD connectors” enables you to analyse rainfall data from different sources over an area defined by the TVD polygon. The rainfall over subcatchments can also be used for a similar purpose, but this feature extends this analysis with the flexibility of using any polygon you want which does not need to be a subcatchment discharging to a network.
The results can then be used for further analysis and in InfoWorks ICMLive the results can trigger alerts that can then generate actions, such as emails with the alerts details, and/or start runs for further analysis, such as detailed runs that should only happen when there is rainfall.

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    About Rui Daniel Pina

    Rui Daniel Pina is the Product Sector Leader of InfoWorks ICMLive. He has extensive experience in hydrology and hydraulic modelling, and provides technical support of Infoworks ICM and ICMLive at Innovyze UK.

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