# Validating an Operational Flood Forecast Model Using Citizen Science in Hampton Roads, VA, USA
## 3 Results
Figure 7 shows an example in Norfolk's Larchmont neighborhood adjacent to a dog park, where flooding is frequent, and the 112 points were used to compare with the light blue modeled flood extents as a linear distance, and averaged to form a mean horizontal distance deviation (MHDD) metric, which yielded an average deviation of 2.67 m for this site during the 2018 king tide. Likewise, several other areas, ranging from residential, commercial, and industrial land uses, during the 2017 king tide are featured in Figure 8. Since Tidewatch Maps provide more than simply a maximum inundation extent, unlike tidal depths estimated from a bathtub model or a sea level rise topographic flood elevation viewer, temporal accuracy can also be assessed through the GPS timestamps reported on each user's measurements through the Sea Level Rise app. Figure 8A,C,E,G, shows a model distance comparison of forecasts and data from 13:00 to 13:59 UTC. Figure 8B,D,F,H show observation data and model forecasted depths for the same sites an hour later from 14:00 to 14:59 UTC. These figures are used to show varying flooding conditions during the king tide on 5 November 2017, which occurred at 14:30 UTC, similar to those noted in Figure 3 during 2011 Hurricane Irene. Figure 8 shows individual sites where monitoring efforts took place in 2017 and ultimately contribute to the overall figure of +/-5.9 m in horizontal difference between the maximum extents predicted via the Tidewatch Maps and the 59,718 high water marks measured through _Catch the King_. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Year** & **Distance (Unique km)** & **Distance (Total km)** & **GPS Points** & **Photographs** \\ \hline
2017 & 104.28 & 416.66 & 59,718 & 1582 \\
2018 & 69.36 & 277.77 & 37,728 & 458 \\ TOTAL & 173.64 & 694.43 & 97,446 & 2040 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: A tabulated table of quantities mapped by _Catch the King_ volunteers in coastal Virginia, USA, where the SCHISM-Driven Tidewatch storm tide model provided inundation forecasts. Figure 8A shows data from the 2017 king tide for the same area as Figure 7 in Larchmont, Norfolk for 44 high water marks collected by 2 citizen scientists from 13:32 to 13:52 UTC to yield a MHDD = 4.18 m. The same site from an hour later is shown in Figure 8B, comprised of 61 high water marks collected by 1 volunteer from 14:30 to 14:39 UTC to yield a less favorable MHDD = 6.92 m during the peak inundation period in _Catch the King_ 2017. Figure 8C depicts annotation during the 2017 king tide along the south bank of the Lafayette River near the Haven Creek Boat Ramp in Norfolk by 73 high water marks collected by 2 citizen scientists from 13:35 to 13:59 UTC to yield an MHDD = 4.67 m. The same site an hour later is shown in Figure 8D, this time featuring 136 high water marks collected by 3 people from 14:30 to 14:47 UTC to yield a less satisfactory MHDD = 6.29 m during the peak inundation period on 5 November 2017. Figure 8E showcases GPS data from _Catch the King_ 2017 for the Lafayette Shores neighborhood, nestled in the east bank of the Lafayette River, through six high water marks collected by a citizen scientist from 13:49 to 13:52 UTC to yield an MHDD = 2.15 m. The same site from an hour later is shown in Figure 8F, comprised of 29 high water marks collected by 2 people from 14:30 to 14:47 UTC to yield a less favorable MHDD = 4.70 m during the peak inundation period. Figure 8G depicts inundation during the 2017 king tide along the north bank of Little Creek in the East Ocean View neighborhood of Norfolk via 93 high water marks collected by 2 citizen scientists from 13:44 to 13:56 UTC to yield an MHDD = 9.81 m. The same site from one hour later is highlighted in Figure 8H, now featuring 68 high water marks collected by 1 person from 14:40 to 14:45 UTC to yield an improved MHDD = 4.06 m during the peak inundation period during _Catch the King_ 2017.