## 4 Outdoor Activities in the Jerte Valley: Canyoning and the 2017 Flash Flood
### The 2017 Flash Flood in Jerte Valley  
The 2017 event was a flash flood that led to four deaths in the same family under the guidance of an adventure company. The deceased were doing canyoning for the first time. The canyon, as already mentioned, was considered suitable for beginners. Only the guide and one of the clients survived the flood. The accident happened at the H-4 site (see Figure 5C,D), where there is a waterfall 15 m in height. Only 30 min later, another flash flood arrived at Papuos canyon at site P-3 (a 30-m waterfall; see Figure 5E,F), with another group of canyoneers under the guidance of a company. In this case, all the canyoneers were unharmed. The timing of the 2017 event is shown in Table 3. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Canyon** & **Difficulty 1** & **Length (m)** & **\# of Rappels** & **Time of Activity 2** & **Season 3** & **Estimated Visitors/Year 4** \\ \hline Hoyos R. & V2, A2, I & 350 & 5 & 15 min/1.5 h/5 min & Sp, S & 4000 \\ Papuos R. & V3, A3, III & 1100 & 9 & 90 min/3.5 h/45 min & Sp, S, Au & 2000 \\ \hline \hline \end{tabular} Note: 1 Source: [PERSON] et al. [19]. 2 Time of activity, divided by approach, descent, and return. 3 Sp: spring, S: summer, Au: Autumn. 4 Estimated visitors only, based on commercial companies.  
\end{table} 
Table 2: Canyoning in the studied area. Rating of difficulty and main characteristics of recreational descent included estimated visitors in commercial uses. Figure 5: Pictures of the canyons studied. (**A**) A frequent open section in Hoyos canyon. (**B**) Site of accident in Hoyos canyon. (**C**,**D**) Papi\(\ddot{\text{o}}\)os canyon before and after the flash flood. (**E**,**F**) The large waterfall where the flash flood arrived (10-min difference). Red stars point out the same positions. \begin{table}
\begin{tabular}{c c} \hline \hline
**Time** & **Activity Development** \\ \hline
11:00 & Start of activity in Los Hoyos canyon (Source: Judicial report, unpublished) \\ \hline
11:30 & Pictures taken by the guide during the activity show scarce discharge at the Los Hoyos canyon (Source: \\  & Judicial report) \\ \hline
11:30 & Start of rain for 5–10 min (Source: Judicial report) \\ \hline
11:43 & Rainfall starts at Papi\(\ddot{\text{o}}\)os stream (Source: Expert Report, unpublished) \\ \hline
11:50 & Increase in water in Papi\(\ddot{\text{o}}\)os stream (Source: Canyoning Company Guia2 _pers. com._) \\ \hline
12:00 & Flash flood arrival at site H-4 in Los Hoyos canyon (Source: Judicial report) \\ \hline
12:21 & Call to emergency services (112) placed by the guide (Source: Emergency Services of the Province) \\ \hline
12:30 & Outdoor agency receives a call from the guide (Source: Outdoor Company Manager, _pers. com_) \\ \hline
12:31 & Picture of Papi\(\ddot{\text{o}}\)os site P-3 before flash flood (Source: Canyoning Company Guia2 _pers. com_), see \\  & Figure 5C,D \\ \hline
12:35 & Flash flood arrival at site P-3 at Papi\(\ddot{\text{o}}\)os stream (Source: Canyoning Company Guia2 _pers. com_), see \\  & Figure 5E,F \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Timing of the flash flood development in both canyons. The water's arrival was sudden; a comparison of pictures (Figure 5C,D) shows that it took just a few minutes for the canyon environment to change dramatically (water depth, viscosity, turbulence, presence of vorticity, etc.). The storm traveled from W to E, and the peak flow reached Los Hoyos canyon (12 a.m.) before Papoios (12:34 a.m., Figure 5F). No one reported signs of anticipated flood arrival, and luckily for the Papoos group, the flood arrived late enough that the one member still to rappel had sufficient time to escape the course of the water. The forecast made by the Spanish Weather Agency (AEMET) predicted rains of 15 mm h\({}^{-1}\), first, and 40 mm in 24 h, later, for the day of the event (a yellow warning), but the rainfall considerably exceeded this amount, reaching 81 mm in 24 h in Jerte, and surpassing 40 mm within the 24-h threshold at all surrounding rainfall stations (see Figure 6A).