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40 2019 ND-CP 413905
- Điều hướng trang này:
- Risk assessment
- Land degradation and soil erosion
| The SCUAF model (Young and Muraya 1990) predicts the response of soils to
specified systems of agriculture, forestry and agroforestry under given environmental conditions. It does not model plant growth. The user inputs initial plant growth, the observed growth under present soil conditions. SCUAF can be applied to the prediction of erosion, soil nutrient decline, soil and plant carbon sequestration, and other changes in soil properties. It is less detailed than many other plant-soil models, but correspondingly easier to understand and apply to obtain results for specific cases. Risk assessment A risk is the chance that some undesirable event may occur. Risk assessment involves the identification of the risk and the measurement of the exposure to that risk. In response to risk assessment, in some cases the risk may simply be categorized as acceptable. In other cases, a mitigation or risk management strategy must be adopted. Such risk management, traditionally a significant activity in the commercial sector (e.g. the insurance industry) has now been adopted in the environmental protection field. Various approaches, expert-based or model-based, can be adopted for risk assessment. In addition to the difference between approaches, there are also differences in the extent to which the methods deal with the environmental problem: some methods adopt a human-centred approach, whereas others view the impact and risk on nature. Land degradation and soil erosion Regional soil erosion risk assessment is needed in order to make objective comparisons that may provide a basis for further land evaluation, planning, environmental analysis, economic statements or policy development. Soil erosion takes place at the field scale, and its temporal and spatial patchiness favours a risk analysis approach in order to make comparisons between regions and to complement field measurements and observations. The main problem is that the spatial resolution of most digital data sets used to quantify the factors causing erosion are too coarse to enable accurate estimation of soil losses at this scale. Land cover, use and management are the most important factors that influence soil erosion, but should be analysed together with natural factors such as topography, soil type and precipitation regime. It is recommended that regularly updated land cover data be used in combination with variables derived from earth observation such as the Normalized Difference Vegetation Index (NDVI) in order to capture changes and seasonal variations in land cover. Existing policies for the protection of soils and the degree of enforcement of such policies should also be monitored. tải về 0.57 Mb. Chia sẻ với bạn bè của bạn:
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