This layer highlights the 1 km channel cells which are upstream of an ERIC flash flood reporting point (Figure 1). The cells are coloured according to the exceedance probabilities of different return period thresholds at the ERIC reporting point at the downstream end of the shaded cells. The rules for shading the cells are shown in table 1 below. The intention of this layer is to highlight the river channel network which may be susceptible to flash flooding.
Figure 1. Example of the ERIC Affected Area Layer shown in the yellow, red and purple shaded cells
| Cell Shading | Extremity Level | Exceedance Probability (P) Class |
|---|---|---|
| Medium | P(RP2 > 15%) & P(RP5 <= 5%) |
| High | P(RP5 > 5%) & P(RP20 <= 10%) |
| Severe | P(RP5 > 5%) & P(RP20 > 10%) |
*RPxx = return period threshold level, e.g. RP5 is the 5 year return period.