Soil degradation is referred to as the reduction of the biological or economical productivity of the soils, due to processes including erosion, change of physical or chemical state (acidification, compaction, salinization) and loss of nutrient or organic matter. Although climatic factors often contribute to cause it, soil degradation is generally related to human activities as deforestation, agricultural intensification and urban expansion. This is the case for the Mediterranean regions of Europe, where erosion processes are particularly severe. Assessment and mapping of erosion risk can be a useful tool for mitigating these phenomena. That can be done by individuating specifical indicators and defining an operative methodology for appropriately weighting and combining them. We have developed a new approach based on multivariate geostatistics and GIS that allows taking into consideration in a flexible way a potentially unlimited number of indicators. This method transforms measured data values into a binary value according to specific criteria. The criteria, developed independently for each indicator, are critical values or ranges of values representing the condition in which the single indicators determine a significant degree of risk. These criteria have to be calibrated locally. Each soil indicator is then mapped as the probability that an area is subjected to the risk of erosion. To interpolate these information, we have utilised an approach based on non parametric geostatistics called indicator kriging. We have then applied factor kriging to define two synthetic weighted indexes summarising the effects of several variables on soil erosion. We present here an example of application to a study area in Sardinia (Italy), which is considered representative of Mediterranean zones at high erosion risk. We selected six variables affecting soil erosion: arable soil depth, organic matter, slope, a texture index, drainage class and land use. We produced maps of both individual soil indicators and synthetic indexes. This procedure allows the identification of both the areas at high erosion risk and the single indicator parameters that cause risk in those zones, thus allowing specific management plans or land use policies to be developed.
Assessment of Soil Erosion Risk Using Multivariate Geostatistics
Canu A;
2003
Abstract
Soil degradation is referred to as the reduction of the biological or economical productivity of the soils, due to processes including erosion, change of physical or chemical state (acidification, compaction, salinization) and loss of nutrient or organic matter. Although climatic factors often contribute to cause it, soil degradation is generally related to human activities as deforestation, agricultural intensification and urban expansion. This is the case for the Mediterranean regions of Europe, where erosion processes are particularly severe. Assessment and mapping of erosion risk can be a useful tool for mitigating these phenomena. That can be done by individuating specifical indicators and defining an operative methodology for appropriately weighting and combining them. We have developed a new approach based on multivariate geostatistics and GIS that allows taking into consideration in a flexible way a potentially unlimited number of indicators. This method transforms measured data values into a binary value according to specific criteria. The criteria, developed independently for each indicator, are critical values or ranges of values representing the condition in which the single indicators determine a significant degree of risk. These criteria have to be calibrated locally. Each soil indicator is then mapped as the probability that an area is subjected to the risk of erosion. To interpolate these information, we have utilised an approach based on non parametric geostatistics called indicator kriging. We have then applied factor kriging to define two synthetic weighted indexes summarising the effects of several variables on soil erosion. We present here an example of application to a study area in Sardinia (Italy), which is considered representative of Mediterranean zones at high erosion risk. We selected six variables affecting soil erosion: arable soil depth, organic matter, slope, a texture index, drainage class and land use. We produced maps of both individual soil indicators and synthetic indexes. This procedure allows the identification of both the areas at high erosion risk and the single indicator parameters that cause risk in those zones, thus allowing specific management plans or land use policies to be developed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
