喀斯特槽谷区土壤侵蚀时空演变及未来情景模拟

以中国南方喀斯特槽谷区为研究对象,基于改进的喀斯特地区土壤侵蚀算法,定量分析了槽谷区土壤侵蚀时空演变特征,并利用CA-Markov模型对土壤侵蚀状况的未来情景进行预测。结果表明:(1)喀斯特槽谷区2000—2015年土壤侵蚀总量由61.86×10~7 t/a减少至2.97×10~7 t/a,区域年平均侵蚀模数由21.61 t hm~(-2) a~(-1)降低至1.04 t hm~(-2) a~(-1),轻度及轻度以下侵蚀等级的面积增加了76.13×10~5 hm~2,重度及重度以上侵蚀面积减少了46.90×10~5 hm~2,侵蚀状况明显减轻;(2)不同地貌类型之间的土壤侵蚀状况存在一定差异,平原地区侵蚀模数最小,盆地地区侵蚀模数最大,达到平原地区侵蚀模数的近4倍;(3) 2000—2015年间,槽谷区轻度及轻度以上侵蚀等级都逐渐向微度侵蚀等级转移,土壤侵蚀等级由高等级向低等级转移率达到了98%以上,总体呈现出好转的趋势;(4)基于CA-Markov模型模拟槽谷区2020年土壤侵蚀等级的未来演变趋势,其总体Kappa系数达到了0.9788,一致性最佳;(5)到2020年,槽谷区土壤侵蚀等级基本为微度和轻度侵蚀,土壤侵蚀状况将进一步改善。本研究的结果可为喀斯特槽谷区当前土壤侵蚀治理成效的评价以及未来的防治提供理论和数据方面的参考。

Spatial-temporal evolution processes and simulation of future soil erosion scenario in the karst valley of Southern China

Based on an improved soil erosion algorithm for the karst area of Southern China, we quantitatively analyzed the spatial-temporal evolution processes of soil erosion, and used the CA-Markov model to predict the future situation of soil erosion in the karst valley in Southern China. Our major findings are as follows:(1) The total amount of soil erosion in the karst valley decreased from 61.86×10⁷ t/a to 2.97×10⁷ t/a from 2000 to 2015, and the annual average erosion modulus of the area reduced from 21.61 t hm^-2 a^-1 to 1.04 t hm^-2 a^-1. The area of erosion corresponding to the grades mild and below mild increased by 76.13×10⁵ hm², while that corresponding to the grades strong and above strong decreased by 46.90×10⁵ hm², indicating that the erosion situation reduced significantly. (2) There are some differences in soil erosion between different geomorphological types. The erosion modulus in the plain area was the smallest, while that in the basin area was the largest, nearly four times the erosion modulus in the plains. (3) From 2000 to 2015, the mild and above mild erosion levels in the karst valley gradually shifted to the level of micro-erosion, and the rate of shift in soil erosion grade from the high to low grade reached more than 98%, showing a general trend of improvement. (4) We simulated the future trend of the soil erosion grade evolution in the trough valley in 2020 based on the CA-Markov model. The overall Kappa coefficient reached 0.9788, and the consistency was the best. (5) By 2020, the soil erosion level in the trough area would be micro-degree i.e., mild erosion and the soil erosion condition would be further improved. The results of this study could provide theoretical and data references for the evaluation of current soil erosion control strategies and future prevention and control measures in the karst valley.