## 3 Applied Methodology
### Study Area  
We tested the 'three indicators' and the'metric grid approach' in the Clamoux River, a left-bank tributary of the Orbiel River, which drains the Montagne Noire then the Minervois Piedmont in the Aude watershed (South of France; Figure 7). The Clamoux River (order 4, Strahler; length: 32.4 km; watershed area: 82 km2) is a confined, single-channel (plane bed or riffle pool) according to [49]. It was chosen as the test river for the proposed method for three main reasons. (i) It is a high-energy river, with a mean gradient of 3.2%, a \(Q_{100}\) 1999 flood of 218 m3/s (for an annual mean discharge of 1 m3/s), which is typical of the intermittent Mediterranean river regime, with a bankfull, specific stream power of 280 W/m2 [2]. This high energy is explained by the boundary conditions of the watershed: high relief (1032 m; max. 1125 m-min. 93 m); Mediterranean climate favorable to flash floods from autumn to spring; the upstream part (mountain; schists) is marked by the rapid concentration (30 min) of water-sediment flows on the slopes (debris flows) and in the confined valley bottoms (hyper-concentrated flows); the downstream part (piedmont; molassic rocks) is characterized by water spreading and alluvial deposition in the floodplain when the river breaches its banks and structures, temporarily becoming a deconfined river. (ii) The Clamoux River experienced several extreme flash floods, including the November 1999 event (35 deaths in the South of France) and more recently, the February 2017 and October 2018 events. (iii) The Clamoux River has been the subject of restoration works since the creation in 2002 of the SMMAR--Syndicat mixte des milieux aquatiques et des rivieres--the basin authority (EPTB) in charge of river management. These restoration works aim to let the river run its own course in zones where it has a tendency during each flood to bypass meanders (artificial channel pattern inherited from the seventeenth- to eighteenth-century embankments) and to open up new braided, active-channel segments. The SMMAR thus buys back the lands bordering the active channel from private owners. The goal is to control the river in its own freedom space, delimited by the stakes in the floodplain. The University of Paris/PRODIG Laboratory has been monitoring these restoration works on the field since the 1999 flood [1,2,50,51,52,53,54].  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**A** & \multicolumn{2}{c}{**Lateral Mobility Rate (_LMR_)**} \\ \hline \multirow{3}{*}{Number of cells with geomorphological change (\(n_{\text{gc}}\))} & Left bank & Right bank \\  & 28 & 22 \\ \cline{1-1}  & Number of cells counted in X-axis (\(n\)) & 40 & 40 \\ \cline{1-1}  & 70 & 55 \\ \hline
**B** & \multicolumn{2}{c}{**Braided Index (B\({}_{\text{I}}\))**} \\ \hline Year A & \multicolumn{2}{c}{0.65} \\ Year B & \multicolumn{2}{c}{0.75} \\ \(B_{\text{I}}\) evolution (in \%) & \multicolumn{2}{c}{13.3} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Application of the _LMR_ indicator (**A**) and the braiding index (**B**) from the theoretical study case.  
In the floodplain of the Chamoux River between the Aygados Bridge and Villegly (Minervois piedmont), we digitized the active channel as it was in 1953, 2008 and 2018. This digitizing was carried out based on orthophotographs provided by the French Geographic Institute (IGN). The French national coordinate reference system (CRS) Lambert 93 (EPSG 2154) is used. It is a metric CRS. The floodplain boundaries were digitized based on field surveys and geological maps. A vineyard is located within the floodplain. In this example, this vineyard will be the infrastructure we want to protect (Figure 8).  
Figure 7: Location of the study area (Clamoux River, Aude watershed, Mediterranean France) (**A**). The Digital Elevation Model (DEM) (**B**) was deduced from the 2018 orthophotograph provided by the French National Geographic Institute (IGN).