土地利用变化对泥沙连通性及泥沙输移的影响——以重庆市涪陵页岩气开采区为例

Effects of Landscape Pattern Change on Sediment Connectivity and Sediment Transport--Taking Fuling Shale Gas Production Area in Fuling Area of Chongqing City as a Case Area

[目的]探究人类活动强烈干扰区景观格局变化对泥沙传输过程的影响,为控制土壤流失为目标的土地利用优化提供科学参考。[方法]运用土壤侵蚀方程、泥沙连通指数等方法分析了页岩气开采区重庆市涪陵区城东片区页岩气开采前后(2010—2019年)土地利用格局的变化,及其泥沙连通性和泥沙输移的响应。[结果]①研究区2010—2019年,耕地减少,建设用地及林草用地增加。②因土地利用格局变化导致的土壤侵蚀变化微弱,整个研究区土壤侵蚀量减小,从2010年的3.12减小到2019年2.78 t/(hm^(2)·a),整个区域的侵蚀策源地是旱耕地。③2010—2019年,整个研究区的连通性指数(IC)呈现减小趋势,从-0.46减小到-0.65,整个区域泥沙输移比减小,泥沙流失量由0.83 t/(hm^(2)·a)减少到0.62 t/(hm^(2)·a)。[结论]土地利用变化除影响土壤侵蚀量外,还影响了泥沙连通性进而减小了土壤流失量。重庆市页岩气开采未造成区域土壤流失发生明显增大,阻断旱耕地的泥沙连通性仍是控制区域土壤流失的有效途径。

[Objective]The effects of landscape change on the sediment transport process were studied in order to provide an important basis for the optimization of land use to control soil loss.[Methods]The earliest shale gas mining area in the eastern part of Fuling District of Chongqing City was selected as the research area.The changes in the landscape pattern before and after shale gas mining between 2010 and 2019 were analyzed.Moreover,the response of sediment connectivity and sediment transport to landscape changes was analyzed.The observing data from 16 runoff plots were used to calibrate sediment loads.[Results]①From 2010 to 2019,the cultivated land decreased,and the construction land,forest and grass land increased;②The change in soil erosion caused by landscape pattern change was weak,and the amount of soil erosion in the entire study area was 2.78 t/(ha·yr)in 2019.The source of erosion in the entire region was dry farmland;③The connectivity index IC of the entire study area decreased from-0.46 in 2010 to-0.65 in 2019.The sediment transport coefficient in the entire region decreased,and the soil loss modulus in the entire region decreased from 0.83 t/(ha·yr)in 2010 to 0.62 t/(ha·yr)in 2019.[Conclusion]The land use change reduced the amount of soil loss by affecting the connectivity of sediment in addition to soil erosion.The shale gas mining in Chongqing City has not caused a significant increase in regional soil erosion.Blocking the connectivity of sediment in dry farmland is still an effective way to control regional soil erosion.