Many catchment areas have suffered from exhaustive changes because of various land use activities over the recent past. These land use changes are associated with intensified environmental degradation witnessed in catchment areas. Such environmental problems include extreme soil erosion. Soil erosion is one of the most critical problems responsible for the degradation of land worldwide. This phenomenon occurs as a result of the complex interactions that exist between natural and human-induced factors. Most factors experience spatiotemporal variations, hence complicating the soil erosion phenomenon. This complexity in the erosion process makes it difficult to quantify soil loss. Without proper information on soil loss, it becomes quite hard for decision-makers and managers to manage catchment areas. However, the availability of soil erosion models has made it easy to estimate soil loss. Many models have been developed to consider these complexities in soil erosion studies. Empirical models such as RUSLE provide a simple and broad methodology through which soil erosion is assessed. The RUSLE model integrates well geographic information system (GIS) and above all remote sensing. This paper presents an overview of the developmental milestones in estimating soil loss using the RUSLE model. The parameterization of the RUSLE model has been adequately reviewed with much emphasis on challenges and successes in derivation of each individual factor. From the review, it was established that different equations have been developed by researchers for modeling the five factors for the RUSLE model. The development of such equations was found to take into account the different variations that depict the soil erosion process.

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Bottom sediments form an integral part of the aquatic ecosystem, where they serve as important sinks for contaminants. However, management options for bottom sediments require an analysis of the physical and chemical properties. Therefore, the aim of this study was to assess the physicochemical properties of bottom sediments in the Maruba dam reservoir in order to inform their potential use. The bottom sediments were obtained from three sampling points using a vibe-coring device. The samples were analyzed for grain size, sediment bulk density, pH, electrical conductivity, organic matter content, and nutrient content (nitrogen, phosphorous, and potassium) using standard laboratory procedures. The results of the study revealed that the bottom sediments were predominantly clay (56%). The mean pH value of the sediments was 6.63, which was found to be slightly acidic. The concentration of cations and anions in the bottom sediments was found to be quite high, with a mean value of 0.225 dS⋅m−1. The bottom sediments in the reservoir were found to be quite rich in the organic matter content (2.10%) and had a mean bulk density of 0.620 g·cm−3. The macronutrients (nitrogen, potassium, and phosphorous) had mean values of 0.12%, 0.46%, and 12.81 mg·kg−1, respectively. The study established that finely grained particles together with organic matter had a potential effect on the availability of macronutrients in bottom sediments. The concentration of the macronutrients of the bottom sediments evaluated in this study points to their potential use in agricultural activities or even in land reclamation.

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Energy and water are the two most important natural resources in the globe. In this regard, dams and reservoirs are the critical hydraulic structures that store water and, above all, provide energy required by humanity. However, water storage and the provision of energy by reservoirs and dams have been disrupted by significant environmental changes taking place in the catchment areas and the reservoir environment. These disruptions are brought about by climatic parameters and sediment transport by different eroding agents. One such environmental problem is soil erosion, whose effect is reservoir sedimentation. Consequently, a part of the transported sediment is deposited at the catchment outlet, which serves as the reservoir inlet. This study was carried out to establish the physicochemical characteristics of the deposited sediment at the reservoir inlet. The following parameters were analyzed: particle size distribution, organic matter content, bulk density, porosity, electrical conductivity, penetration resistance, hydraulic conductivity, pH, and nutrients (nitrogen, phosphorous, and potassium) using standard laboratory procedures. The study established that the deposited sediments were predominantly sand particles with mean values of 50.60% and 58.60% for the surface (0–10 cm) or sub-surface horizons (10–20 cm), respectively. The average values for sediment pH, organic matter, porosity, bulk density, electrical conductivity, penetration resistance, hydraulic conductivity, and nutrients were 6.30 and 6.61; 1.91 and 1.80%; 54.10 and 57.10%; 1.22 and 1.14 g·cm−3 for the surface and sub-surface horizons, respectively. The most variable parameters were silt content (sub-surface horizon), hydraulic conductivity, penetration resistance, electrical conductivity, nitrogen content (surface horizon), and phosphorous (surface horizon) content with CV >0.35. Based on the present study results, the deposited sediments at the reservoir inlet were found to have low concentrations of nutrients and high sand proportions. Therefore, the deposited sediments appear to have great potential to reclaim the immediate barren dam environment upon enrichment and to promote sand harvesting programs for economic benefits.