## 4 Discussion  
The dynamics of LULC change and erosion can be both influenced by and contribute to climate change. These interconnected processes underscore the pressing need for the implementation of sustainable land management practices and proactive adaptation strategies. These approaches could effectively alleviate the consequences of climate change on our ecosystems and landscapes, promoting environmental resilience and long-term sustainability. Landscape changes were identified across five specific dates within the timeframe spanning from 1980 to 2020, utilizing the available data. The forest has decreased over the 40-year period from 1980 to 2020 by about 26%, and this class has been encroached by rangeland and cropland. The SWC implementations were increased to reach almost 30% of the watershed surface. The results indicate a trend towards a higher proportion of the very slight erosion intensity class and a decrease in the other erosion classes, except for the very severe class, which remained stable in the study watershed. This indicates a transition from more pronounced erosion intensity to the subsequent lower level of erosion classification. The regions exhibiting the greatest soil loss were identified in the steepest areas of the studied watershed, aligning with similar patterns observed in other semi-arid regions of Tunisia, like the Rmel watershed [36; 37]. Furthermore, the calculated soil erosion rate within the study watershed closely aligns with the erosion rate derived from bathymetric data [36] and various other studies carried out in the same region,  
Figure 15: Predicted and observed NSL at sub-watershed outlets. such as Khlifi [37]. These findings indicate that without effective management of current land use and land cover changes, and if the conservation structures' effectiveness continues to deteriorate, certain implications could arise. Thus, it is probable that soil erosion will persist in the future. The alteration in soil erosion rates within the study area between 1980 and 2020 was primarily due to the increase in LULC categories vulnerable to erosion (cultivated land and rangeland) and the reduction in vegetation coverage, particularly the forest, which is less susceptible to erosion. However, it seems that SWC implementations reduce the impact of LULC changes. The landscape behavior is more complex and depends on the interaction of all the watershed erosion factors. Sediment retention pertains to the ecosystem's ability to regulate and control the quantity of eroded sediment that enters the hydrographic network. Sediment retention quantifies the extent to which the present land use mitigates soil loss in comparison to a scenario with exposed bare soil while accounting for the SDR factor. The combined approach of the RUSLE and the SDR model is employed to assess the sediment retention capacity of individual land parcels, leveraging data on LULC. Consequently, changes in LULC degradation can lead to an increase in soil loss and a decrease in sediment retention. Notably, within the study watershed, it was observed that sediment retention rates surpassed soil loss, a trend commonly observed in semi-arid regions [38]. The consequences of the rise in the \"very slight\" category and the decline in the other categories suggest a shift of regions with substantial sediment yield to a lower sediment yield classification. The areas exhibiting the greatest sediment yield align with the locations characterized by the highest levels of soil erosion and SDR. Taking these relationships into account, certain areas might exhibit elevated erosion rates yet have a low SDR, indicating that the sediment yield in these areas would not be considerable due to the low SDR. On the other hand, having a higher SDR alone does not necessarily lead to increased NSL unless the GSL rate is also higher. The average annual sediment yield established through this investigation corresponds to findings from other studies conducted in the semi-arid region of Tunisia.