## 4 Discussion
Additionally, the calculated sediment yield aligns with the data that have been recorded. The observed decrease in sediment yield within the study watershed from 1980 to 2020 can be predominantly attributed to the increased adoption of SWC measures within the watershed. When examining different rates of GSL and NSL intensities, the comparisons revealed that within the \"very slight\" intensity, the sediment yield exceeded soil erosion. Specifically, the sediment yield was recorded between 59.2% and 47.6%, while the soil erosion measured 75.6%. As previously discussed, the regions experiencing the most significant soil erosion were located in areas with steep slopes, whereas areas with gentle slopes exhibited the lowest erosion levels. Consequently, the observation of a higher sediment yield in the \"very slight\" intensity level, as opposed to the soil erosion, is logically consistent. In areas with gentle slopes, deposition tends to exceed erosion, accounting for this phenomenon. Conversely, the phenomenon of lower sediment yield in regions characterized by a \"very severe\" erosion intensity, when compared to soil erosion, can be rationalized. This is because, in areas with steep slopes, erosion tends to exceed deposition. Due to its varied environmental consequences, the LULC changes have become a worldwide issue [39; 40; 41]. The fundamental environmental challenge in Tunisia is rooted in the alterations of LULC, particularly the growth of cultivated land at the expense of forested regions [42]. The transformations in LULC have additionally influenced the rate of soil erosion and sediment yield, as evidenced by studies [3; 43; 44; 45; 46]. They are also the primary catalysts that have significantly transformed ecosystem services [47; 48; 49]. Numerous investigations have been conducted in Tunisia concerning changes in Land Use and Land Cover (LULC) [21; 42] as well as sediment yield [2]. Worldwide, there is limited research specifically dedicated to quantifying the impact of LULC changes on soil erosion and sediment yield [50; 51; 52; 53]. The outcomes of the study align well with prior research conducted in the semi-arid climate of Tunisia. For instance, as demonstrated by [PERSON] et al. [54], the expansion of croplands at the cost of natural vegetation has had detrimental effects on the region's natural resources. Likewise, [PERSON] et al. [55] highlighted that the intensive plowing and overgrazing aimed at fulfilling the demands of the local population within a specific Tunisian watershed have led to ongoing soil degradation. This degradation encompasses heightened erosion and sediment accumulation in reservoirs. It is important to emphasize that agriculture in Tunisia has experienced substantial transformations since the early 20 th century, resulting in a significant erosion crisis. The spatial analysis conducted in this study unveiled that the expansion of cultivated land onto soils more susceptible to erosion was the predominant factor driving the escalation of soil erosion potential within the watershed throughout the study timeframe (1980-2020). Gaining insight into the spatial distribution of erosion is crucial for addressing soil loss issues effectively by implementing suitable SWC techniques. In the Merguellil watershed, croplands and rangelands have been equipped with bench terraces since 1990. Despite this, the natural forest coverage continues to decline, steep slopes are being cultivated, and overgrazing persists due to the fast population growth. Implementing optimal agricultural practices and employing effective tillage techniques would prove advantageous in mitigating soil erosion and reducing sediment yield.