不同土地利用方式下赤红壤坡面土壤侵蚀特征

为探究降雨和土地利用对南方赤红壤坡面侵蚀特征的影响,通过天然降雨观测试验,定量分析不同土地利用方式(坡耕地、果园、人工草地和撂荒地)下坡面径流和侵蚀泥沙特征,探讨降雨类型及土地利用对坡面侵蚀产沙的影响以及降雨特征参数与坡面水沙指标间的关系。结果表明:(1)2018年研究区降雨主要集中在5—9月,且每月降雨量主要由一场或几场暴雨及大暴雨组成;(2)坡耕地坡面年径流量和年侵蚀量均最大,分别是果园、人工草地以及撂荒地处理下的3.4,8.0,6.0倍和340.5,1605.3,1720.3倍;(2)次降雨下,坡面径流量在年内表现为前期平稳,后期波动增加,侵蚀量表现为前期波动较大,后期变化相对平稳,且侵蚀产沙主要集中在前期;(3)不同土地利用方式下,暴雨及大暴雨产生的径流量均占年径流量的75%以上,坡耕地、果园、人工草地以及撂荒地处理下由暴雨和大暴雨产生的侵蚀量分别占年侵蚀量的99.1%,71.8%,52.3%和51.6%;(4)降雨量和最大30min降雨强度是影响赤红壤坡面侵蚀最重要的降雨特征参数,降雨历时和植被覆盖度均显著影响果园、人工草地及撂荒地坡面径流量。研究结果有助于明晰南方赤红壤区不同土地利用现状土壤侵蚀特征,为区域水土保持提供参考依据。

Slope Soil Erosion Characteristic of Lateritic Red Soil Under Different Land Use Types

In order to explore the impact of rainfall and land use on the slope soil erosion characteristics of lateritic red soil in South China, the runoff and erosion sediment characteristics of different land use types (slope farmland, orchard, artificial pasture and abandoned land) were analyzed quantitatively through the observation experiment of natural rainfall, and the impact of rainfall types and land use on the erosion and sediment yield of slope, as well as the relationships of rainfall parameters and slope water and sediment were discussed. The results showed that the rainfall in 2018 was mainly from May to September, and the monthly rainfall was constituted by one or several rainstorms and heavy rainstorms. (2) The annual runoff and erosion of slope farmland were the largest, and the runoff amount of farmland was about 3.4, 8.0 and 6.0 times of orchard, artificial pasture and abandoned land, respectively, and the sediment yield of slope farmland was about 340.5, 1 605.3 and 1 720.3 times of orchard, artificial pasture and abandoned land, respectively. (3) Runoff amount on the slope surface kept a stable level during the early period of the year, then the fluctuation increased during the late period of the year, while the trend of sediment yield was opposite to that of runoff amount, and the erosion and sediment yield were mainly concentrated in the early period. (4) Runoff generated by heavy rainstorm and large heavy rainstorm accounted for more than 75% of the annual runoff for all land use types, while the erosion generated by heavy rainstorm and large heavy rainstorm accounted for 99.1%, 71.8%, 52.3% and 51.6% of the annual erosion for slope farmland, orchard, artificial pasture and abandoned land, respectively. (5) Rainfall amount and maximum rainfall intensity in 30 min were the most important parameters for soil erosion, and rainfall duration and vegetation coverage also significant affected runoff amount for orchard, artificial pasture and abandoned land. The results were helpful to clarify the soil erosion characteristic of lateritic red soil under different land use status and provide reference for regional water conservation of South China.