# Geohydroology of a Reference Mediterranean Catchment (Cilento UNESCO Geopark, Southern Italy)
## 2 Materials and Methods
### Geomorphometric Analysis  
To objectively characterize the overall asymmetry of the headwater catchment, sub-catchments and hydro-geomorphotypes mapped in Figure 3, a basic geomorphometric analysis was carried out. This analysis focused on the basic parameter distribution useful for streamflow source areas and pathways that control the different behavior of the left and right valley side and, for each one, the response of a distinctive hydro-geomorphotype. The analysis was performed in ARCGIS(r) software using specific tools to derived the digital elevation model (DEM) with a 5 m cell size (Figure 5a) from the regional technical map (CTR) of the Campania Region, at a scale of 1:5.000. A correction of DEM was set to eliminate the errors \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Station Type for**} & \multirow{2}{*}{**Number**} & \multicolumn{3}{c}{**Collected Parameters**} & \multirow{2}{*}{**Temporal Resolution**} & \multirow{2}{*}{**Mode**} \\ \cline{3-3} \cline{5-6}  & & **Q** & **D** & & & \\ \hline Main & 1 & x & x & x & Daily/Sub-hourly & Automatic \\ Sub-stations & 4 & x & & x & Weekly & Manual \\ Secondary & 23 & x & & x & Weekly & Manual \\ Springs & 13 & x & & x & Monthly & Manual \\ Hollow & 16 & & x & x & Montly & Manual \\ Weir V-n notch 90\({}^{\circ}\) & 16 & & x & x & Daily & Semi-automatic \\ Piezometers & 16 & & x & x & Weekly & Manual \\ Control points & 30 & x & x & x & After heavy storms & Manual \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of the monitored points with the collected parameters and time-steps. D: water depth; Q: discharge; EC: electrical conductivity (modified from [8]). Figure 4: High-frequency (5 min) discharge (Q)—electrical conductivity (EC) dataset, collected at the outlet catchment (blue line: Q; green line: EC). due the DEM extraction procedure, such as pits, applying the \"pit removal\" tool of the ArcGIS10 (Figure 5b). This procedure allowed us to obtain a hydrologically corrected DEM in order to clearly extract significant hydrological parameters, such as: slope (Figure 5c), flow direction (Figure 5d), flow accumulation (Figure 5e) and stream network (Figure 5f). Other geo-morphometric significant parameters were extracted, such as stream order (Figure 5g), wetness index (Figure 5h) and landforms (Figure 5i), using the Spatial analyst, Grid Calculator and ArcHydro tools in ArcGIS10. The extracted maps were projected to the regional reference system (WGS 1984 UTM Zone 33 N). The classification and distribution of the elevation and slope parameters [41] are basic but important for analysis in all hydro-morphometric studies as they are strongly controlled by lithology and geological  
Figure 5: Basic derived maps from the digital elevation model (DEM) with a 5 m cell size. (**a**) Extracted DEM 5 x 5 m; (**b**) Difference map between DEM and Filled DEM; (**c**) Slope; (**d**) Flow direction; (**e**) Flow accumulation; (**f**) Stream network; (**g**) Stream order; (**h**) Wetness Index (WI); and (**i**) Topographic Position Index (TPI) (classes: 1: incised stream; 2: midslope drainages, shallow valley; 3: upland drainages, headwater; 4: U-shaped valley; 5: plains; 6: open slopes; 7: upper slopes, mesas; 8: local ridges/hills in valleys; 9: midslope ridges, small hills in plains; and 10: mountain tops, high ridges). structures, such as the strata attitude, discontinuities and joints, climate and morphogenetic processes and the landform evolution stage. The concept of stream order was introduced by [42] and it is a widely applied method for stream classification in a river basin, as a measure of the position of a stream in the hierarchy of tributary network [43]. The wetness index (WI) was calculated (Figure 5h) as proposed by [44]:  
\[\text{WI}=\text{ln(As/tan }\beta), \tag{1}\]  
where As is the upslope area derived from the flow accumulation and tan \(\beta\) is a tangent function of slope as the percent-rise.