In recent decades, Algeria has experienced rapid and irregular demographic growth, and this irregular change has inevitably led to periodic floods threatening human life. Urbanization, an anthropogenic cause, is rapidly evolving and has been considered as a non-negligible part in altering land use and land cover (LULC), despite the fact that precipitation characteristics are related to the climate of the region and may change over time. It is therefore essential to assess the changes in runoff as a result of LULC changes. Awareness of the relationship of rainfall and runoff is necessary for urban drainage network modeling and design. The implementation of Low-Impact Development (LID) is a popular strategy to minimize stormwater runoff and pollutant loads. In developed countries, software to estimate impacts of certain LID controls has expanded in recent years; however, readily available modeling approaches are still in high demand in developing countries, such as Algeria. In this article, we seek methods that can decrease runoff peaks and volume for the Guelma watershed located in northeast Algeria by integrating the Personal Computer Storm Water Management Model (PCSWMM) and a geographic information system (GIS). PCSWMM calibration is conducted by using the sensitivity-based radio tuning calibration tool. The Nash–Sutcliffe efficiency (NSE) (0.70–0.88), coefficient of determination (R²) (0.76–0.96), and relative error (RE) (0.018–0.23) indicated good model performance in this urban watershed. The implementation of five LID practices, including permeable pavements, bioretentions, rain gardens, infiltration trenches, and rainwater harvesting systems, in scenarios explored could reduce peak runoff by 54.7% and reduce total runoff volume by 75.2%. The current research will assist decision-makers in improving and choosing the most appropriate LID designs that are effective in view of future climate changes and changes in LULC. This study can contribute to further applications of rainfall–runoff models in Algeria.