黄土丘陵沟壑区不同土地利用方式下小流域侵蚀产沙特征

Characteristics of Erosion and Sediment Yield in Small Watersheds Under Different Land Use Patterns in Hilly and Gully Region of the Loess Plateau in China

为进一步优化和合理配置水土保持措施,以黄土丘陵沟壑区3个不同土地利用方式下的坝控小流域为例,基于人工探槽取样、淤积层次甄别及与产流降雨事件的对应关系,结合1∶10000早期地形图与全站仪测量,拟合库容曲线来估算淤地坝泥沙淤积量,进而反演坝控流域的产沙模数变化特征。结果表明:(1)延河马家沟3个不同土地利用方式下的洞儿沟、阎桥和芦渠坝控小流域,自建坝至2016年的多年平均淤积量分别为2748.80,4634.31,3141.17 t;(2)洞儿沟、阎桥和芦渠流域多年平均产沙模数分别为2432.56,3131.29,1794.95 t/(km^(2)·a),依次属于轻度、中度和轻度侵蚀;不同土地利用方式下坝控小流域的最小产沙降雨量均>20 mm以上;(3)不同的土地利用方式对小流域侵蚀产沙影响显著,人类活动明显的阎桥流域多年平均产沙模数大于以林草地为主的洞儿沟流域,而以林地和梯田为主的芦渠流域多年平均产沙模数最小。由此可见,在黄土丘陵沟壑区合理配置不同的水土保持措施,是减少小流域侵蚀产沙的有效途径。

For further optimization and rational allocation of soil and water conservation measures,three small watersheds under different land use patterns in loess hilly and gully region was taken as an example.According to the sedimentation profile sampling,siltation layer identification and corresponding relationship with erosive rainfall events,the capacity curve of the check-dams was established combined with 1∶10000 early topographic map and Total Station measurement to estimate the sediment deposition,and then the sediment yield was determined based on the controlled watershed area and performance period.The results showed that:(1)The multi-year average sediment depositions in Dongergou,Yanqiao and Luqu dam-controlled small watersheds under different land use patterns from dam construction to 2016 in the Majiagou catchment of Yanhe River basin were 2748.80,4634.31 and 3141.17 t,respectively.(2)The multi-year average sediment yields of Dongergou,Yanqiao and Luqu watersheds were 2432.56,3131.29 and 1794.95 t/(km^(2)·a),which were mild erosion,moderate erosion and mild erosion,respectively.The minimum rainfall of erosion and sediment yield in the dam-controlled small watershed under different land use patterns was greater than 20 mm.(3)Different land use patterns had significant effects on the erosion and sediment yield in small watersheds.The multi-year average sediment yield of Yanqiao watershed with obvious human activities was larger than that of Dongergou watershed with lots of forest and grassland,while the multi-year average sediment yield in Luqu watershed was the smallest with mainly forest and terraces.Thus,it could be concluded that the reasonable configuration of different water and soil conservation measures in loess hilly and gully region is an effective way to reduce erosion and sediment yield in small watersheds.