The watershed of Oued Rumell covers an area of 5,668 Km2 (Table 1), representing more than 60% of the total area of the larger basin of KebirRumell to which it belongs. Its relief is characterized by an average altitude of 800 meters. The Oued Rumel is 150 km long and its main tributary, the Oued Boumerzog, is about 50 km long. The main city along the two wadis is Constantine, home to 42% of the basin's population. (Fig. 2)
The limits of the Oued Rhumel:

To the east, the Seybouse basin

To the south, the basin of the Constantinian high plateaus.

To the north, the Kébir Rhumel basin and the Constantinian coastline
Its boundaries extend beyond the territory of the Wilaya of Mila and reach several neighboring Wilayas: Constantine and Oum elBuasi in the east, Batna in the south, Setif in the west, Jijel and Skikda in the north, are in a subhumid bioclimatic stage with low thermal variability of winter type and an average annual rainfall of 662.8 mm/year. The average annual temperature is 19.33℃. (Koussa and Bouziane 2018)
Geologically, the hydrological catchments present more or less complex topographic and structural mosaics, the results of which are a wide variety of quantitatively and qualitatively diverse groundwater resources. The Terian aquifer over the entire northern half of the paleogeography basin is distinguished from north to south and from north to south.
The ultraterian aquifers, Terian strict sense, Penetrian and Numidian, little developed in our basin, are found in the northeastern part of the mountains Djebel elWahch and near Ain Abid, and south of Siggs, Djebel Ohm Settas.
Table 1
Some morphometric parameters of the oued Rhumel watershed
Physical parameter  Symbol  Unit  Value 

Superficie  S  km2  5308 
Perimeter  P  km  353,5 
Gravilius index  KC  /  1. 35 
Length of equivalent rectangle  L  km  137,56 
Width of equivalent rectangle  l  km  39,02 
Average altitude  Hmoy  m  806,39 
Maximum altitude  Hmax  m  1481,5 
Minimum altitude  Hmin  m  184,6 
Global slope index  IG  m/km  3,45 
Specific gradient  Ds  m  252,8 
Average slope index  Imoy  /  0.0102 
Density of graining  Dd  Km− 1  0,056 
Coefficient of torrentiality  Ct  Km/km4  0,0001 
Time of concentration  Tc  Hours  29 
The frequency of the watercourses  F  km− 2  0,0018 
Data collection and analysis
Various hydrological indices were calculated using a geographic information system with a DEM of 30 × 30 m and Arcgis software was used to extract the Stream power index (SPI), the Compound topography index (CTI), Topographic Wetness Index (TWI), Curvature and the Sediment Transport Index (STI) with slope (in degrees) and Flow accumulation is used as input data. After calculating the slope and the various indicators above, we reclassified each indicator/parameter into four categories and assigned weights based on their vulnerability to erosion, the various maps obtained were overlaid using the weighted sum tool of Arcgis software to obtain an erosion risk map.
Slope
Slope plays an important role in influencing surface and subsurface flow velocities, runoff rates and vegetation development (Chang and Tsai 1991), at the slope scale, precipitation and resulting runoff drive the evolution of water erosion and slope morphology through the exchange of soil materials and runoff energy (Shimin et al. 2023)
The slope (S) represents the angle (in degrees) between the horizontal plane Y and the tangent plane X at a given point on the topographic surface (Lehmann 1816), is evaluated by the following equation:
\(S=arctan{\text{ }}{\left( {{Y^2}+{X^2}} \right)^{\frac{1}{2}}}\)
Curvature
Curvature is an index for finding patterns of soil erosion and water distribution over the land. Longitudinal curvature affects the acceleration and deceleration of flow, which affects erosion and deposition. Curvature of the region affects the convergence and divergence of flow (Imran et al, 2019), Threedimensional slope and slope curvature data and relative point position are important factors in modeling erosion and water flow (King et al. 2005; Jeiner and Luis, 2016).
Planform curvature
It is the second derivative of the altitude and depends on the orientation and inclination.It is the horizontal curvature of the contour (Wilson and Gallant 2000). Positive means the landform is convex, negative means it is concave, and means it is flat. Convex curvature means flow divergence, concave curvature  flow convergence.
Profile curvature
Defined as a curve of the vertical plane of the streamline. It affects flow acceleration, erosion, and deposition rates (Wilson and Gallant 2000; Neteler and Mitasova 2008; Kennelly 2008). Convex curvature accelerates flow and erosion processes, while concave curvature affects sedimentation processes.
The topographic wetness index
The topographic wetness index also called the topographic index or composite topographic index, is a parameter that describes the tendency of cells to accumulate water, (Quinn et al. 1991), influences important environmental processes, controlling plant growth, dispersal and community formation (Fan et al. 2019)
Soil moisture controls environmental processes and species distribution, but is difficult to measure and interpolate spatially, is commonly used to quantify topographic control over hydrologic processes. (Sørensen et al. 2006). Soil moisture is one of the most dynamic components of soil, changing seasonally and fluctuating, often daily, with changes in precipitation, evapotranspiration, infiltration and runoff. (Daly and Porporato 2005)
Stream power index
This parameter has been widely used in erosion, sediment transport, and geomorphic studies to measure the erosive power of flowing water; Flow is assumed proportional to drainage area (Moore et al. 1991). The SPI determines the erosive power of the channel and expresses the potential for topographic deposition (for low or negative values) and the erosive zones (for positive values). (Imran et al. 2019), The SPI of the study area was calculated by Raster Calculator of Arcgis software using the following formula:
\(SPI=Ln{\text{ }}(Flow{\text{ }}Accumulation+0.001)/((Slope/100){\text{ }}+{\text{ }}0.001)\)
Sediment Transport Index
Sediment transport capacity is one of the most important factors influencing soil erosion (Li et al. 2020) This greatly affects the movement process of soil erosion (Zhang 2018). Sediment transport capacity is a comprehensive index of the balance between sediment deposition and transport. In addition, it is necessary to study sediment production, sediment transport and sediment deposition.
\(STI=\left[ {\left( {m+1} \right)\left( {\frac{{{A_s}}}{{22,{{13}^m}}}} \right){{\left( {\frac{{\sin \beta }}{{0:0896}}} \right)}^n}} \right]\)
Where As is the specific area of the watershed (the upstream area per unit contour length); B is the local slope in degrees; the participating area exponent m is generally set to 0.4 and the slope exponent n is generally set to 1.4
Topographic roughness index
Topographic Roughness Index (TRI) and The Topographic Moisture Index (TWI) are secondary geomorphometric parameters used to describe and quantify landform.. (Różycka et al. 2016)
Terrain roughness is a valuable attribute of wildlife habitat models and an important factor in vegetation diversity, snowmelt, and drainage, which are key components of nutrient uptake (Daniel and Getachew 2019)
Channel density
In 1945, Horton (Horton 1945) defined an unchannelled slope as a corrosion zone with insufficient flow power to generate corrosion. Later, Montgomery and Dietrich (Montgomery and Dietrich 1992) and Dietrich et al (Dietrich et al. 1993) verified his thesis. According to Marani et al (Marani et al. 2003), drainage viscosity is defined in practice by a statistical distribution and the correlation structure of unchannelled path lengths. According to Prabu and Baskaran (Prabu and Baskara 2013), runoff viscosity is expressed in lock distance and reflects the soil structure of the kilometer point.
Distance to channels
Particle transport distance may reflect the effectiveness of channel morphology in facilitating deposition sites for sediment passage (Wilcock 1997)
Although the advent of fast survey techniques (such as terrestrial laser scanning (Williams et al. 2013) has facilitated the resolution of this problem, much of our understanding of morphological control of particle path length is inevitably the result of a laboratory channel