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Abstract Soil erosion probability maps were produced under various case scenarios by accounting for uncertainties in the data and in the decision rule, using the Universal Soil Loss Equation (USLE), remote sensing and geographical information systems (GIS). This objective was realized by applying the Bayesian Probability Theory within IDRISI, a raster based GIS. The outcomes were two continuous probability soil erosion maps ranging from zero to 1. Comparing these maps with an earlier study indicates that accounting for the uncertainties has, in general, decreased the probability of soil erosion. Based on average readings for specific sites on the maps, increases in erosion risk under the second case scenario have had the highest impact on the highlands that is in the central, eastern, and northern regions of Langkawi Island, Malaysia. Assuming a 10% risk, this impact has increased by 11.98, 11.83 and 5.741% for high, medium and low soil erosion risk areas on the island respectively. 相似文献
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BIM与3DGIS技术的结合可以连接室内室外,实现城市精准三维建模,更好地推进智慧城市的建设。IFC与CityGML分别作为BIM与3DGIS的通用标准,利用本文提出的基于语义映射的方法,可以实现IFC到CityGML几何与语义信息的转换,并以标准模型进行了验证。 相似文献
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依据灾害系统理论,从生态环境脆弱性、气候变化影响风险性及社会经济暴露性三方面出发,构建中国大陆沿海城市自然灾害风险评估体系。采用乘法计算模型,即风险=脆弱性×危险性×暴露性,求得自然灾害综合评价指数。分析探究中国大陆53个沿海城市自然灾害风险特征,识别高风险、高脆弱性区域。 相似文献
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Accessibility is a factor affecting national park visitation. However, the effect of accessibility on national park visitation is not fully understood. This paper examines the relationship between U.S. national park visitation and accessibility. First, the global and local accessibility indexes of each park unit are computed based on an accessibility model that takes into account the surrounding population and its proximity to the park unit. Integrated in the model is a distance decay coefficient that is derived from U.S. national park visitor surveys and therefore pertinent to the case of study. Then correlation analysis is performed between park visitation and accessibility based on park types, regions, and visitation types. Results show that total visitation is positively related to accessibility in National Memorials, Military Parks and Battlefield Parks/Sites but negatively related to accessibility in national parks and national monuments. However, recreational overnight stay visits are commonly negatively correlated to accessibility for almost all park types. Moreover, local accessibility index displays enhanced correlation coefficients with improved significance levels in many categories of analysis. Results suggest that historical/cultural national parks which often show positive correlations tend to attract more local visitors, but nature-based parks which mainly show negative correlations tend to attract more distant visitors. 相似文献