Land degradation assessment: tools and techniques for measuring sediment load
The assessment of land degradation through the use of tools and techniques is discussed for the measurement of sediment load in regions of great agricultural potential, such as the Paraná river basin. Land degradation for these prominent agricultural regions is defined as being the actions in land that decreases potential crop production over time. Assessment of land degradation by erosion (soil loss by water, e.g. topsoil removal, rilling and gullying), chemical (carbon and nutrient depletion) and physical degradation (soil compaction and disaggegation, emergence of subsoil with poor physical properties) and the causes of degradation (deforestation, overexploitation, overgrazing and agricultural activities) in these regions are addressed. The effects of land degradation through water erosion and its subsequent impact on rivers and reservoirs downstream are presented through the use of modeling tools and techniques. A methodology for the utilization of models such as the Revised Universal Soil Loss Equation (RUSLE) or the Water Erosion Prediction Project Model (WEPP) to assess the risk of land degradation in large scale agricultural lands is presented as well as the techniques used for continuous monitoring. Issues and problems with the adaptation of a small scale erosion models to function as a large scale risk assessment tools are also addressed. The integration of these models with tools such as geographic information system (GIS) and the use of various thematic maps derived from satellite imagery and land surveys to feed the models is an essential part of this methodology. The identification of high degradation risk areas will allow for better soil conservation planning where programs can be implemented to maintain a sustainable non-degrading agricultural system and thus, reduce the sediment load into rivers and lakes in the region of interest.