Soil Erosion

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Soil erosion is a major concern in the southeastern region of Nigeria due to high population densities and farming techniques, which has resulted in the presence of numerous gullies. While gullies are found all around the world, the existence of gullies in Nigeria is regarded as one of the worst environment disasters, having negative implications on the environment and the quality of life for humans and other species (Adetona & Ezezika, 2011; Ajaegwu & al, 2010). Large quantities of soil in Nigeria are being lost each year due to gullies, and action needs to be taken. Gullies have altered the appearance of landscapes and lifestyles that civilians once enjoyed, forcing them to relocate elsewhere. Recent increases in the Nigerian population growth have further perpetuated the problem of gully formation as less land is suitable for farming and living (Hudec & al, 2005). As soil erosion occurs, the soil and nutrients are washed away and lost, creating channels or cuts in the ground, known as gullies (Ofomata, 1984). Weathering rocks are loosened by wind and rain, thus exposing the layers of soil formerly hidden under the ground. Soil erosion is a continuous process, and it is indeed very problematic, thus leading to the formation of gullies (Ofomata, 1984). The rate at which gullies are developing and expanding is definitely a cause for alarm. Gully expansion in southeast Nigeria has officially become an environmental hazard where a number of civilians have been forced to move somewhere else, and now more regions are becoming unsuitable for living (Adetona & Ezezika, 2011). There are four major factors contributing to soil erosion and gullies in Nigeria. The first two factors are geologic components and anthropogenic or human components. The geologic or natural components of soil erosion are caused by weathering processes such as wind, rain, mudslides, and landslides, which cause the soil to recede (Ofomata, 1984). The rocks underlying the soil tend to be porous, allowing water to filter through them, thus contributing to soil erosion. The anthropogenic components of soil erosion are caused by human activities such as agricultural techniques, deforestation, and poorly designed roads (Ofomata, 1984). The poor farming methods damage the land, thus setting up the stage for gully formation. A couple other significant factors are Nigeria’s climate and topography. Nigeria's climate is a humid, tropical climate (Hudec & al, 2002). Average temperatures range from 25 degree Celsius to 27.5 degrees Celsius, and the average number of hours of sunlight is 1750 hours (Ajaegwu & al, 2010). The climate of Nigeria is characterized by heavy rains, and Nigeria receives substantial rainfall, receiving at least 2000 mm of rainfall each year, thus contributing to gully formation (Ofomata, 1984). Torrential rainfalls usually occur at least five times per year with rainfall accumulations averaging at least 100 mm per rainfall, and wind gusts are strong, also contributing to soil erosion as soil particles are forcefully washed away (Adetona & Ezezika, 2011). The diameter and the speed at which raindrops fall are important prerequisites for gullying activities. Flooding is an important factor in gully formation, and gullies result from concentrated runoffs of rain water in specific locations that have accumulated after rainfalls (Ofomata, 1984). Nigeria’s topography or landscape is prone to gullying. The landscape is characterized by mostly flat slopes with a few rolling hills and sandy coastal plains, which are very susceptible to gullying, allowing water to accumulate in areas and form gullies (Hudec & al, 2002). An important feature of gully formation is soil erodibility. Soils high in silt and organic matter but low in organic matter tend to be the most erodible, which is an important risk factor for gully development. The soils in southeast Nigeria tend to be highly erodible (Akpokodje & al, 1998). Rainforests are found in the southeastern region...
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