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Climate change and soil vulnerability under anthropogenic impact on the Dapaong-Bombouaka escarpments in northern Togo
Published in Jürgen Runge, Assogba Guézéré, Laldja Kankpénandja, Natural Resources, Socio-Ecological Sensitivity and Climate Change in the Volta-Oti Basin, West Africa, 2020
L. Kankpénandja, D. Bawa, B. Afo, T.Y. Gnongbo, A.B. Blivi
The assessment of the influence of anthropogenic impact on the Dapaong-Bombouaka escarpments was studied through the dynamics of land use. A precise mapping of the land use was made from Landsat TM and ETM+ images with a resolution of 30 m. It revealed since the 1980s by a strong extension of the exploited areas. It results in a weak protection of the land surface increasing soil erodibility. The question of the impact of anthropogenic factor on land in the Savannah Region has also been addressed by other such as Addra et al. (1986), Kankpénandja & Alassane (2012) and Kankpénandja (2016) who all revealed a strong anthropic pressure manifested by a rapid expansion of land used areas at the expense of natural vegetation. At the national scale, studies on land degradation status by Brabant et al. (1996) and land use by Afidegnon et al. (2003) confirm these findings. Brabant et al. (1996) attribute land degradation to various anthropogenic factors including unsuitable agricultural practices, overexploitation of vegetation, late and uncontrolled bush fires, overgrazing, commercial and industrial activities. The map of Afidegnon et al. (2003) reveals that, outside protected areas, vegetation in the north of Togo consists mainly of savannah “parks” degraded by agropastoral activities. Different studies carried out in the West African sub-region have also shown the role of anthropogenic impact on erosion. This is the case of Mietton (1988), Dipama (1996a, 1996b), Bandré (2000) and Bouzou Moussa (2000), evidenced anthropization in Burkina Faso and Niger resulting in the advancement of land degradation.
Erosion by Water: Vegetative Control
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
Seth M. Dabney, Silvio J. Gumiere
Vegetation controls erosion by dissipating the erosive forces of rainfall and runoff (erosivity) and by reducing the susceptibility of soil to erosion (erodibility). Vegetation alters the partitioning of rainfall between infiltration, surface storage, and surface runoff. Erosivity is reduced because rainfall kinetic energy is absorbed, runoff volume is reduced due to increased infiltration, and runoff velocity is slowed through increased surface detention and reduced development of areas of concentrated flow. Vegetation also reduces soil erodibility by increasing soil aggregation, binding aggregates together with roots, and lowering soil matric potential. Vegetation may cover the entire soil surface, as with crops, cover crops, or forests, or it may be limited to specific critical areas, as with various types of conservation buffers. This entry reviews the mechanisms and processes by which vegetation reduces soil erosion by water and decreases yield of sediment and associated pollutants from agricultural fields. Emphasis is placed on vegetative buffers. Crop residue effects are considered in another entry.
Governing Processes
Published in Michael S. Majewski, Paul D. Capel, Pesticides in the Atmosphere, 2019
Michael S. Majewski, Paul D. Capel
Wind erosion of formulation dusts, small granules, and pesticides bound to surface soil is another mechanism by which applied pesticides reach the atmosphere, although it is generally considered to be less important than volatilization (Glotfelty and others, 1989). Factors that influence the erodibility of soil include horizontal wind speed, precipitation, temperature, soil weathering, and cultivation practice (Chepil and Woodruff, 1963). Very large particles (500 to 1,000 μm diameter) tend to roll along the ground and, generally, do not become airborne, but they can break apart into smaller particles or dislodge small particles from the surface as they roll. Particles in the size range of 100 to 500 μm diameter move by saltation, a skipping action that is the most important process in terms of the wind erosion problem and in moving the greatest amount of soil when there is a long downwind fetch (Nicholson, 1988b). Although large and saltating size particles can move horizontally great distances, depending on the wind speed, their vertical movement is rarely above one meter (Anspaugh and others, 1975) and they are usually deposited near their source.
Assessing the effectiveness of community-based watershed management practices in reversing land degradation in the Finchwuha watershed, Gojjam, Ethiopia
Published in International Journal of River Basin Management, 2022
Asnake Mekuriaw, Tadesse Amsalu
The average annual soil loss rate in the study area was 49.5 t ha−1y−1 in 2003 and 23.8 t ha−1y−1 in 2019 (Table 6). The annual soil loss ranged between 0–262.3 t ha−1y−1 in 2003 and 0–226.7 t ha−1y−1 in 2019. The highest annual soil loss was observed in the steep slope areas and in areas where there is sparse vegetation cover and poor soil conservation measures. In line with this, Nunes et al. (2011) observed that soil erosion increases with a decrease in soil cover with vegetation. Blake et al. (2020) asserted that the improvement of vegetation cover helps reduce soil erodibility. Correspondingly, Farhan et al. (2013), Zhang et al. (2014) and Zhao et al. (2019) found a high soil erosion rate in steep slope areas compared to similar land uses on flat land.
Country-scale spatio-temporal monitoring of soil erosion in Iran using the G2 model
Published in International Journal of Digital Earth, 2021
Shahin Mohammadi, Fatemeh Balouei, Khadijeh Haji, Abdulvahed Khaledi Darvishan, Christos G. Karydas
Soil erodibility is a lumped parameter that represents an integrated annual value of the soil profile’s reaction to the process of soil detachment and transport by raindrop and surface flow (Veihe 2002). S-factor is estimated preferably from direct measurements in natural plots (Panagos et al. 2014b). However, this is not financially sustainable at the regional/national level (Renard et al. 1997); thus, G2 proposes alternatives when direct measurements are not possible. In the present study, the soil input data for Equation (8) were extracted from the Harmonized World Soil Database (HWSD) (Verelst and Wiberg 2012).
Estimating soil loss for sustainable land management planning at the Gelana sub-watershed, northern highlands of Ethiopia
Published in International Journal of River Basin Management, 2018
Birhan Asmame Miheretu, Assefa Abegaz Yimer
The soil erodibility factor (K) is the soil loss rate per erosion index unit for a specified soil as measured on a unit plot (Wischmeier and Smith 1978). It reflects the characteristics of the soil and is a measure of the susceptibility of the soil particles to detach and be transported by rainfall and runoff (Haile and Fetene 2011). Some soil types are naturally more prone to soil erosion due to their physical structure. Erodibility is a function of soil texture, organic matter content and permeability (Balasubramani et al. 2015).