基于RUSLE模型的妫水河流域土壤侵蚀时空变化特征

[目的] 为揭示流域土壤侵蚀时空变化特征并开展可持续流域治理工作。[方法] 基于妫水河流域1995—2018年降雨、土壤、数字高程模型及土地利用数据,采用GIS技术与RUSLE模型的方法定量分析妫水河流域土壤侵蚀时空特征,并对流域土壤稳定性进行评价。[结果] (1)1995—2018年,流域内林地和草地面积均呈下降的趋势,2018年林地和草地面积分别为4.41×10⁴,0.84×10⁴ hm²,较1995年分别下降13.52%和10.61%。耕地面积由1995年的3.53×10⁴ hm²增加至2018年的4.07×10⁴ hm²。建筑用地面积逐渐增加,由1995年的0.59×10⁴ hm²增加到2018年的1.90×10⁴ hm²。(2)妫水河流域内土壤侵蚀模数呈波动性变化,由1995年的8.71 t/(hm²·a)降至4.56 t/(hm²·a)后,于2018年升至11.07 t/(hm²·a)。(3)妫水河流域土壤侵蚀强度以微度侵蚀和轻度侵蚀为主,1995—2015年,土壤侵蚀强度逐渐降低并保持稳定,中度及以上土壤侵蚀面积比例由4.95%降至3.05%,2018年后升至7.42%。(4)妫水河流域在研究时段内土壤稳定性降低,不稳定土壤面积升高。[结论] 妫水河流域城市化的进程中,林草覆盖度略有降低;土壤侵蚀强度整体下降,但在后期略有提高;不稳定土壤所占面积较少。研究结果可为妫水河流域综合治理及土地利用规划提供依据。

Spatialand Temporal Variation Characteristics of Soil Erosion in Guishui River Basin Based on RUSLE

[Objective] Detecting the spatial and temporal variation characteristics of soil erosion in river basins and carry out sustainable river basin management. [Methods] This study quantitatively analyzes the temporal and spatial characteristics of soil erosion in Guishui River Basin by RUSLE model based on the rainfall, soil, digital elevation model (DEM) and land uses datasets of Guishui River Basin from 1995 to 2018, meanwhile, the soil stability in the basin was evaluated. [Results] (1) The areas of forestland and grassland showed a decreasing trend from 1995 to 2018, respectively. In 2018, the areas of forestland and grassland were 4.41×10⁴ and 0.84×10⁴ hm², respectively, which were 13.52% and 10.61% lower than those in 1995. The farmland area increased from 3.53×10⁴ hm² in 1995 to 4.07×10⁴ hm² in 2018. The area of building land has gradually increased, from 0.59×10⁴ hm² in 1995 to 1.90×10⁴ hm² in 2018. (2) The soil erosion modulus in Guishui River Basin fluctuated from 8.71 t/(hm²·a) in 1995 to 4.56 t/(hm²·a), and then increased to 11.07 t/(hm²·a) in 2018. (3) The intensity of soil erosion in Guishui River Basin is mainly in slight erosion. From 1995 to 2015, the intensity of soil erosion gradually decreased and remained stable, and the proportion of moderate and above erosion area decreased from 4.95% to 3.05%, and increase to 7.42% after 2018. (4) In Guishui River Basin, the soil stability decreased and the unstable soil area increased during the study period. [Conclusion] In the urbanization process of Guishui River Basin, the coverage of forest and grass decreased slightly; the intensity of soil erosion decreased totally, but increased slightly in the last stage; unstable soil land takes up a small proportion. The results of this study provide a basis for comprehensive management and land use planning of Guishui River Basin.