Land Degradation

An overview of the Geospatial Methodologies used in order to assess the Soil Erosion Risk by water. 1.2 The damages on Land are traduced in " Soil Erosion " , " Soil Degradation " and/or " Ecosystem Decline " .. Introduction The Soils constitute one of the most important of the world's natural resources. Life on earth is totally dependent on well management of soils (Agurgo, 1996). Into of the ecosystem, the soil plays a crucial role in biochemical and geochemical cycling, partitioning of water, storage and release, buffering, energy partitioning, which are essential for supporting ecosystems. The balance among these functions could be changed either by succession of natural events like volcanic activity, or by continuous large-scale human activities (Kimpe & Warkentin 1998). Soil quality relates to the chemical, physical and biological properties of the soil, and how these are distributed throughout the soil profile. Scientists use an array of indicators to describe soil quality: pH, organic matter content, plant-available nutrients, porosity, grain size distribution, water permeability and retention capacity, topsoil depth, presence of chemicals toxic to plants or plant consumers, etc. These properties vertically vary within the soil profile and horizontally from site to site. They also interact. Therefore, soil quality cannot easily be described by one variable or an index. Crop yields alone are not a good proxy as they depend on water, fertilizer, seed variety, and crop management practices in addition to soil quality. However, measuring yield trends while controlling for other inputs and management can provide an observable and credible measure of trends in soil quality (López Falcon, 2002). Besides this main function being the base for the production of biomass, soils perform other important functions for human life. On the one hand act filtering, buffering and transforming adverse compounds that pollute the environment, protecting the food chain pollution and water underground, and comprise a gene pool, which is more complete quality and quantity of all the land biota (López Falcon, 2002). Activities like deforestation, overgrazing, cultivation of marginal lands, and introduction of irrigation without providing for adequate drainage, mining and industrialization for meeting the increasing demand for food, fuel and fiber for ever-growing population have led to over-exploitation of natural resources, resulting in the deterioration of erstwhile healthy ecosystems (Dwivedi, 2002). Globally, 1,964.4 million ha of land are affected by human-induced degradation. Of this, 1,643 million ha are subject to soil erosion by water, …