###### Abstract
It is an essential factor in sediment yield modeling and erosion control planning, different equations and models provide estimates of the sediment delivery ratio based on different landscape and environmental factors [16; 17]. It is crucial to emphasize that the accuracy of these predictions relies on input data accessibility and quality, along with the assumptions incorporated into the models [18]. Recognizing the consequences of changes in LULC on soil erosion patterns, sediment transportation, and the delivery of ecosystem services is of the highest importance when crafting holistic approaches for successful watershed management. Numerous investigations have been carried out to evaluate the influence of LULC changes [19; 20; 21] on soil erosion and sediment yield [22; 23]. These investigations provide valuable insights into the relationship between land use alterations and erosion processes. Moreover, multiple studies have illustrated the advantages of SWC techniques in mitigating soil erosion. In Africa, terracing has proven to be highly effective in decreasing soil erosion, preserving water, and retaining nutrients at the watershed scale [24]. Similarly, in semi-arid regions of China, these methods have been shown to significantly diminish sediment runoff on hillsides [25; 26]. Despite the critical importance of understanding the combined effects of Land Use and Land Cover (LULC) changes and SWC techniques on soil erosion, a limited number of studies have specifically addressed this aspect. Additionally, the majority of published studies have focused on assessing short- or medium-term effects more than long-term impacts. Meta-analyses of SWC impact assessments have revealed a lack of studies that offer consistent, long-term quantitative evidence of the impacts of SWC on erosion at the watershed scale [23]. Furthermore, the sediment delivery ratio (SDR) model plays a crucial role in accurately estimating the quantity of sediment yield originating from individual units within a watershed. This model serves as a fundamental tool for assessing the transport and deposition of sediment, aiding in the understanding of how erosion processes impact the overall sediment load and contributing to informed decision-making for sustainable land and water management practices. Thus, the SDR has been extensively utilized in various studies [16; 17]. However, various equations and models have been developed to predict the sediment delivery ratio based on different factors, and they vary in their structure, their assumptions, and the factors they consider. Most of the equations used topographic factors [18]. The primary objective of this paper is to analyze the spatiotemporal patterns of water erosion in the Merguellili catchment area from 1980 to 2020 and evaluate its consequences. Specifically, the purpose is to investigate alterations in water erosion and sediment production, which are influenced by shifts in land use and the implementation of SWC techniques. Furthermore, the research aims to analyze the repercussions of these changes on both the watershed and sub-watershed scales. By accomplishing these goals, the study aims to provide important information on the changing erosion patterns and their environmental repercussions. This can contribute to more effective watershed management and conservation practices. More specifically, this study conducted a comprehensive long-term analysis of the combined impact of LULC change and SWC structure implementation on soil erosion over a period of 40 years. The integration of RUSLE and SDR methodologies allows for the quantification of the possible impact of alterations in land use on soil erosion and sediment yield. This information is essential for comprehending the outcomes of diverse land management practices during the studied timeframe. The used SDR model incorporates both topography and LULC changes.