International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 04 | Apr 2025
p-ISSN: 2395-0072
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Rainfall-Runoff Modelling Using SCS-CN and Geospatial Techniques in the Mubuku Catchment, Uganda Derick Samuel1, K . Deepa2 1Department of Artificial Intelligence and Data Science, Loyola Institute of Technology, Chennai 600123, India. 2Department of Civil Engineering, Chennai Institute of Technology, Chennai
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Abstract – Climate change is a major factor which impacts
sustainable way. There by the economy of a region or country can be saved.
on rainfall extremes and drought extremes all over the world. In this research the study area Mubuku River basin, faces such extremity of rainfall every year resulting in huge volume of sediment transportation to the river. Thus, as an initial step, the rainfall runoff quantity has been thoroughly carried out according the nature of the topography, soil and rainfall intensity. Techniques such as SCS method and geospatial tools are applied in determination of runoff quantity of the study area. Five years of rainfall data from 2020 to 2024 was used and respective runoff quantity has been computed. The highest runoff computed of 45568 m3 for the year 2024 and the lowest runoff of 28672 m3 computed for the year 2020. It was also observed a gradual increase of runoff throughout the five years in the study area.
2. LITERATURE REVIEW Water resources management is a critical aspect of sustainable development, particularly in regions where agriculture and domestic water supply are heavily reliant on rainfall (Govindaraju, et al, 2024). Assessing water availability by evaluating the relationship between rainfall and runoff is therefore of paramount importance for effective watershed management, flood prediction and control of soil erosion. Rainfall-Runoff (RR) modelling is therefore needed to predict the responses of a watershed to precipitation events. There are so many methods of modelling that are used in hydrology such as SCS-CN, SWAT, SHE, WaSIM and VIC Models among others (Yoshe, 2025), (Solomon Eniyew, et al, 2024). In this study, the Soil Conservation Service-Curve Number (SCS-CN) method has been employed because of its simple and requires minimum input data. The method is based on the concept of curve numbers (CN), which represent the runoff potential of a watershed based on Soil Type, Land Use and Land Cover (LULC), Antecedent Moisture Conditions (AMC) (Chen, J., Hill, A. and Urbano, L. 2010). In the domain of flood management, this methodological approach significantly enhances forecasting, the establishment of early warning systems, and the design of flood control infrastructure. Additionally, it facilitates the identification of areas susceptible to flooding. Furthermore, the methodology contributes to water harvesting and the management of land use to promote sustainable agricultural practices. It is predominantly employed to evaluate the impacts of climatic variations on water resources. This method was formulated by the United States Department of Agriculture (USDA) and is recognized as one of the most extensively utilized techniques for estimating direct runoff resulting from precipitation (USDA, 1972), (USDA, 1985) and was originally modelled for conditions prevailing in the US. Since then, it has been adapted to conditions in other parts of the world (Govindaraju, et al, 2024). Notwithstanding the advancements made by certain regional centers in developing supplementary criteria, the fundamental concept remains widely applied globally. The method is well established because of its stability and ability to incorporate various factors contributing to runoff, including both spatial and non-spatial data sets such as daily and monthly
Key Words: SCS method, Curve Number, Rainfall, Runoff, GIS, hydrologic soil
1. INTRODUCTION The climate is a major determinant of water conditions through its influence on the hydrological cycle (Vörösmarty et al., 2000). Changes in climate patterns can impact water systems through shifts in temperature, rainfall, and extreme weather events (Intergovernmental Panel on Climate Change [IPCC], 2021). Changes in climate patterns like increases in global temperatures (Stocker et al., 2013), shifts in precipitation regimes (IPCC, 2021), and more frequent/severe extreme weather events (IPCC, 2021) can directly impact surface and groundwater systems. Altered rainfall and flooding patterns modify watershed hydrology and influence runoff volume/quality (Barnett et al., 2005). Rainfall-runoff is a mathematical model which directly relates with the basin characteristics such as slope, soil type, stream density and size of the basin (K Deepa, M Krishnaveni, 2012). Rainfall extremes result in flooding which further results in pollution of surface and subsurface water contaminations, spreading of water borne diseases and transportation of sediments to surface water bodies, further resulting in reduction of storage capacity of the reservoir. On the other hand drought extremes result in reduction in soil moisture condition, decline of water table and reduction of agriculture of a country. Thus, it is essential to monitor any regions or basin or watershed the extremes of those hazards, in order to manage the environment in a
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