基于CSLE和抽样调查的泰国土壤水蚀评价

通过对泰国区域土壤侵蚀的定量评价,掌握泰国土壤水蚀特征,以期为泰国土壤侵蚀防控和相关研究提供技术和数据支撑。采用CSLE模型,基于30 m分辨率区域侵蚀因子综合运算完成泰国土壤水蚀速率计算(地图代数法制图),基于亚米级分辨率抽样调查完成抽样单元水蚀速率计算,再以抽样单元计算结果为参考,对地图代数制图结果进行直方图匹配,最终获得研究区土壤水蚀速率专题图。结果表明:(1)直方图匹配制图结果既保留了原有的空间分布特征,又具有准确的统计特征。(2)泰国平均土壤水蚀速率为687.9 t/(km²·a),是全球平均土壤水蚀速率的2.4倍,个别地区达到1 000 t/(km²·a)以上(占面积13.2%,占侵蚀总量72.0%),与全球平均水蚀速率相比,土壤水蚀较为严重,0.6%的区域年侵蚀量约占研究区侵蚀总量的21.5%,局部侵蚀剧烈。(3)在各土地利用类型中,耕地水蚀最为严重,平均水蚀速率高达1 020.2 t/(km²·a),水蚀速率>2 500 t/(km²·a)的热点地区84.1%区域为耕地。由此可知,泰国局部区域的土壤水蚀较为剧烈,耕地对区域水土流失的贡献较大。

Assessment of Soil Water Erosion in Thailand Based on the CSLE Model and Sampling Survey

Through the quantitative evaluation of soil erosion in Thailand, the characteristics of soil water erosion were mastered in order to provide technical and data support for soil erosion prevention and control and related research in Thailand. The water erosion rate in Thailand was calculated by using the CLSE(Chinese Soil Loss Equation)model. The water erosion rate in Thailand was estimated based on the comprehensive calculation(map algebraic mapping)of the erosion factor from 30 m resolution maps, the water erosion rate for the sampling units was calculated based on the sub-meter resolution sampling survey. The map algebra mapping results were calculated for the sampling units from the reference map using histogram matching. Finally, the thematic map of soil water erosion rate was obtained. The results showed that:(1)the histogram matching results not only retained the original spatial distribution characteristics, but also had accurate statistical characteristics;(2)the average soil water erosion rate in Thailand was 687.9 t/(km²·a), which was 2.4 times of the global average soil water erosion rate; in some areas, it reached to more than 1 000 t/(km²·a)(accounting for 13.2% of the total area, and 72.0% of the total erosion); compared with the global average soil water erosion rate, soil water erosion in Thailand was more serious; the annual erosion in 0.6% of the area accounted for about 21.5% of the total erosion in the study area, and local erosion was severe;(3)among the land use types, the water erosion of cultivated land was the most serious, and the average water erosion rate was 1 020.2 t/(km²·a). 84.1% of hot spots, soil loss >2 500 t/(km²·a), were cultivated lands. It can be seen that soil water erosion is severe in some parts of Thailand, and cultivated lands contribute greatly to regional soil erosion.