# A Systematic Revision of the NFIP Claims Hazard Data in Florida for Flood Risk Assessment
## 3 Results and Discussion
### NFIP Claims Hazard Revision
#### 3.1.3 Summary of Revised Claims  
The provided and revised NFIP claim counts and paid loss amounts with percentages are shown in Tables 2 and 3, respectively. Before our revision, the majority of flood loss causes in Florida were considered due to the accumulation of rainfall (53.1% in claim count and 46.6% in paid loss), followed by surges (29.4% in claim count and 36.6% in paid loss). Hence, it can be misinterpreted that the main flood cause of loss in Florida was accumulation of rainfall. After our systematic revision, this misinformation was dramatically changed to the following: the main cause of flood loss in Florida was storm surge events. Tidal water overflow now explained 46.4% of claims by count and 65.0% of paid losses. While there was just a ca. 17% increase in claim count, there was an increase of more than USD 1 billion (USD 2415 million out of 3714 million) in the paid loss amount. Figure 6: NFIP cause of loss revision—incorrect surge claims. All circles denote the provided NFIP surge claims. Red circles denote revised surge loss claims, while blue circles denote incorrect surge claims. Figure 7: NFIP cause of loss—Hurricane Ivan (2004). Red dots denote surge claims, and blue dots denote accumulation of rainfall claims. Domain: \(-\)87.21 W to \(-\)87.04 W and 30.3 N to 30.4 N.  
A summary of the general types of meteorological events and their respective portions of the claim data is provided in Table 4 for the revised NFIP events. In this table, it can be seen that hurricanes were by far the primary cause of flooding damage in Florida, accounting for 72.1% of the revised claim losses and 54.5% of claims by count. The losses labeled tropical storm and depression did not reach hurricane strength while damage occurred. These events accounted for approximately 13% of the losses in the revised claims. While the losses for tropical storms were lower than for hurricanes, the number of potential events that may need to be considered could be larger. Tropical storms may produce lower surges than hurricanes, but the rainfall from such storms can often be quite significant. The third class of general flood hazard events in Table 4 was nonotropical systems. These events are usually heavy rainfall events that are not caused by tropical systems. These events, however, do include nontropical cyclones, such as the _Storm of the Century_(March, 1993). These cyclones can cause surges as well as heavy rain. Currently, the FPFLM does not have any model to take these types of events into account. Table 5 shows the detailed breakdown of NFIP paid losses due to each type of meteorological events and cause of loss. For hurricane events, approximately 80% of paid losses were due to storm surges. Meanwhile only 21.6% were due to surges in tropical storm events. The accumulation of rainfall explained 9.5% for hurricane, 58.5% for tropical storms, 81.9% for tropical depressions, and 49.1% for nontropical events. The importance of nontropical cyclone events to storm surges and associated coastal inundation was examined through the NFIP claim data. Based on the revised NFIP, the number of nontropical surge claims was 10,564 (~7% of the paid claims and ~15% of storm surge claims), accounting for paid losses of USD 179,719,000 (~5% of the paid claims and ~7.6% of storm surge claims). The Storm of the Century accounted for 5875 surge claims out of total 8846 claims, amounting to paid losses of USD 132,764,000 (79%) for coastal surge claims.