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标题：Mapping and Monitoring of the Impact of Gully Erosion in Southeastern Nigeria with Satellite Remote Sensing and Geographic Information System
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作者：J. I. Igbokwe ; J. O. Akinyede ; B. Dang 等
期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2008
卷号：XXXVII-B8
页码：865-872
出版社：Copernicus Publications
摘要：Gully Erosion, in part, explains soil erosion. Soil erosion is described as an accelerated process under which soil is bodily displaced and transported away faster than it can be formed. The agents of soil erosion are principally running water, glaciers, waves and wind. These are natural agents of erosion. Anthropogenic factors also contribute to soil erosion, particularly in this zone. Erosion usually transports rocky materials or soil particles after the processes of weathering have broken them down into smaller pieces which are moveable. Soil erosion starts with the delayed type of rainfall droplets, dislodging particles of soils, removing them and eventually depositing them at new location different from the original site. When the surface of soil is not protected by plant covers or any other materials, it erodes or washes away easily. An area is subject to erosion when certain factors are considered. These include geology, landuse practices, geomorphology, climate, soil texture, nature and biodiversity, land conservation practices and environmental management. Soil erosion constitutes the major ecological problems in Southeastern Nigeria. Three types of soil erosion occur in the area, namely sheet, rill and gully erosion. Gully erosion is however the most prominent feature in the landscape of Southeastern Nigeria. The topography, geology, nature and texture of soil, vegetation as well as activities of man contribute to the speedy development and expansion of gullies in the area. The focus of this research project is therefore on gully erosion and its impact in Southeastern states of Anambra, Abia, Enugu, Imo and Ebonyi. Gully erosion in this area is a causative action of nature and man (anthropogenic factors). Man, in most cases remain nonchalant, unconcerned to the consequences of his actions and inactions to the environment. The natural causes of gully erosion are also indirect actions of man which in some cases are even orchestrated for political reasons. In the cause of this study we identified such activities as laterite excavations, bad farming practices, unplanned road construction and urbanization, wood harvesting for fuel and bush burning to clear lands for farming, among others. These activities, coupled with annual flooding from rain water are causing havoc and untold hardship as gullies continue to develop and expand rapidly in the area. Utilizing the opportunities offered by Remote Sensing and Geographic Information System (GIS), this research project came up with vital spatial datasets on the spatial distribution, development and impact of gully erosion in Southeastern Nigeria. This paper therefore presents the results of this study, which include
关键词：Land Degradation; Landcover; Landuse; Topography; Soil Erosion; Settlements; Gullies; Vegetation