基于“3S”技术的南京市水土流失定量监测及分析

为定期对南京市水土流失开展动态监测,利用降雨资料、土地利用资料、环境卫星遥感数据、土壤和地形数据,采用“监测水土流失的定量新方法”,计算2011—2015年南京市水土流失。结果表明:①2011—2015年5 a平均南京市水土流失总量为201.42万t,其中,轻度以上水土流失面积为515.75 km²,水土流失量166.77万t,占全市水土流失总量的82.8%,轻度以上水土流失治理仍是水土流失治理中的重点;②5 a中2015年水土流失最严重,2013年则最轻,其中降雨侵蚀力R_i大小为决定因素;③5 a平均极强烈与剧烈水土流失量为分级侵蚀量中最大;④与2001—2010年10 a平均相比,2011—2015年5 a平均南京市微度水土流失面积增加7.6%,轻度以上水土流失面积减少42.5%,轻度以上年水土流失量减少23.7%,CP值的减小是2011—2015年5 a平均水土流失状况改善的主要原因;⑤3次水土流失定量监测表明,2011—2015年监测强烈、极强烈的水土流失面积和年水土流失量减幅下降,剧烈的水土流失面积和年水土流失量增大,主要原因是2011—2015年降雨侵蚀力R_i (5 a)平均值较大。研究成果为南京市水土保持规划和水土流失防治提供了重要的基础数据支撑和科学参考依据。

Quantitative Monitoring of Soil Erosion Loss in Nanjing by RS,GPS, and GIS

A set of novel methods quantitatively monitoring soil erosion loss is employed to calculate the soil erosion loss in Nanjing City in 2011-2015 according to data of rainfall, land use, soil and terrain, and environmental satellite. Results revealed that: (1) From 2011 to 2015, the average total amount of soil erosion loss in Nanjing is 2.014 2 million tons, among which above light level (above level II) soil erosion is 1.667 7 million tons, occupying an area of 515.75 km² and accounting for 82.8% of the total amount; soil erosion above level II remains a focus of control work. (2) With rainfall erosivity R_i as a decisive factor, the most severe soil erosion happened in 2015, while the slightest in 2013. (3) The five-year average amount of extremely severe (level VI) and severe (level V) soil erosion ranks top among the grading. (4) Compared with ten-year average in 2001-2010, the area of slight (level I) soil erosion in 2011-2015 increased by 7.6%, while the area of erosion above level II reduced by 42.5%, with the amount cut by 23.7%; the decrease in CP(vegetation cover and preservation measure) is the main cause of such mitigation in 2011-2015. (5) In 2011-2015, the decrease in area and amount of level IV and V alleviated; while the area and amount of level VI exacerbated due to large value of rainfall erosivity R_i (five-year average in 2011-2015). The research achievements offer important fundamental data support and scientific basis for the soil and water conservancy planning and soil erosion control in Nanjing City.