Water erosion is a serious threat in the Hamdara watershed. It mainly manifests itself in the form of gully erosion, which directly results in the silting up of low-lying areas and basins. The objective of this study is to characterise the spatio-temporal dynamics of gully erosion at the scale of the Hamdara watershed and to quantify the sediment flow deposited at the alluvial cone. The methodological approach adopted is based on remote sensing and topography, in particular the use of DGPS for intra-annual monitoring of two representative gullies (R1 and R2). The gully network has grown from 91 gullys totalling 77.72 km in 2005 to 213 gullys representing 127.33 km in 2024, an average increase of 2.61 km/year. Drainage density increased from 0.51 km/km² in 2005 to 0.83 km/km² in 2024, representing an increase of 42.33%. The total volume of eroded soil from R1 and R2 is estimated at 742,176 m³. R2 gully, which is more active, accounts for 596.93 m³ alone. Finally, the extension of the R2 gully cone reached 1,212 m² (17% of the initial area). This dynamic is now significant and needs to be taken into account in the fight against the silting up of basins.
