# Application of the KINEROS 2 Model to Natural Basin for Estimation of Erosion
## 2 Description of Study Basin Characteristics  
The study basin is located in the north hillside of the transverse valley of Encamp, a town located in Andorra, as shown in Figure 1a. Encamp (Andorra) has a mountainous Mediterranean-type climate, with a cold winter with heavy snowfalls, and a hot summer. Being a dry climate, the annual minimum average is \(-2\)\({}^{\circ}\)C, and the maximum is \(24\)\({}^{\circ}\)C. Average annual rainfall ranges between 770 mm and 1100 mm. These precipitations are given in the form of rain in spring and autumn and mainly in the form of snow in winter.  
Rainfall data used in this study comes from _Roc de Sant Pere_ station, located 4 km away from our study area. It is the closest station and provides 6-minuretainfall data. In this study the rainfall events of 2012 were used and are shown in Table 1.  
The study basin, called Aviar Basin, is a peri-urban basin of 0.35 square kilometers. The elevation ranges are from 1.310 to 2.195 m above the sea level and the average slope of the basin is 51%.  
In order to determine the surface soil composition of the basin, two samples of 30 cm depth were taken in Encamp to do a granulometric analysis using the sieving technique [3]. Analysis of the samples revealed that the surface soils are combined and mixed with big rock masses of Caradoc's conglomerate, a very typical rock in the Pyrenees between the surface and a depth of 50-80 m. According to the Geological Map of Andorra [15], this material comes from the Ordovician epoch. The characteristics of sampled soils are summarized in Table 2.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Rainfall Event** & **Start** & **Stop** & **Total Rainfall (mm)** & **Duration (min)** \\ \hline Event 1 & 21 March 2012 11:00 & 21 March 2012 17:18 & 22.6 & 384 \\ Event 2 & 21 March 2012 22:18 & 22 March 2012 03:00 & 14 & 288 \\ Event 3 & 22 March 2012 12:00 & 22 March 2012 22:06 & 13.4 & 606 \\ Event 4 & 23 March 2012 08:42 & 23 March 2012 16:12 & 20.2 & 456 \\ Event 5 & 2 As in the rest of the Principality of Andorra, forests and shrubs cover a big part (2/5) of the extension in Encamp. Oaks predominate up to an elevation of 1200 m, with white pines being more common above that elevation. At elevations of 1600-1700 m, up to 2.200-2.300 m, black pines and alpine meadows predominate. The most common ground cover in the study area is forest and shrubs, as shown in Figure 2b.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Sample 1** & **Sample 2** \\ \hline Fine & 24.2\% & 33.2\% \\ Sand & 22.3\% & 13.3\% \\ Gravel & 53.5\% & 53.5\% \\ D10 * & 0.08 mm & 0.08 mm \\ D50 & 2.55 mm & 2.39 mm \\ D80 & 15.08 mm & 21.33 mm \\ Structure type & Granular fine & Granular fine \\ Soil type based on USC ** & Sand (SM *** or SC ***) & Sand (SM *** or SC ***) \\ \hline \hline \end{tabular}  
* D10: Particle diameter of 10% of soils classified as Fine; ** Unified Soil Classification System, ASTM D, 2487–83 [16]; *** Silty sands, sand–silt mixtures; *** Clayes sands, sand–clay mixtures.  
\end{table}
Table 2: Soil characteristics of the two samples [3].  
Figure 1: Study area description: (**a**) Location of study area in Andorra. (**b**) Digital elevation model (DEM) for the Aviar Basin (www:icc.cat, accessed on 17 December 2013) [3].