Bernardi Felipe, Minella Jean P G, Dambroz Alice Prates Bisso, Schlesner Alexandre, Merten Gustavo H, Mao Luca, Evrard Olivier, Piccilli Daniel Gustavo Allasia, Dalmolin Ricardo Simão Dinis, de Araújo Pedron Fabrício
Graduate Program in Soil Science, Federal University of Santa Maria, Santa Maria, Brazil.
Department of Soils, Federal University of Santa Maria, Santa Maria, Brazil.
Environ Monit Assess. 2024 Dec 3;197(1):9. doi: 10.1007/s10661-024-13440-1.
The dynamics of fluvial erosion responds to soil erosion and surface runoff on hillslopes due to land use and environmental fragility, conditioned by the soil, geology, relief, and rainfall rate. Despite the increasing problems associated with fluvial erosion in Brazil, little information is available on bedload transport in headwater catchments under intense agricultural activity. Therefore, this study sought to characterize the fluvial erosion processes and bedload dynamics in an experimental catchment in southern Brazil located at the edge of the Brazilian Meridional plateau, which is representative of a large area of high environmental fragility and intense agricultural activity in Southern Brazil. The Guarda Mor River drains a headwater catchment (18.5 km) with undulating and hilly terrain with fragile soils and intense agricultural activity controlling fine and coarse sediment supply downstream. During 11 major rainfall-runoff events, monitoring was conducted to measure streamflow, bedload transport rates, sediment size, and hydraulic parameters, such as Manning's n values and viscous layer thicknesses. A rating curve was established based on 40 streamflow and bedload discharge measurements taken at different water levels and stages along the hydrograph. In addition, a river portion (gravel bed) was characterized as well as the granulometric characteristics of its surface and subsurface layers. The results showed that the transport pattern is influenced by factors other than hydraulic parameters alone, including the interdependence between successive events, armoring effects, and hysteresis. These factors are strongly related to the surface runoff and erosion observed on the hillslopes, which define the streamflow energy and the supply of sand fraction, respectively. A discussion is held on the bedload transport dynamics under non-equilibrium conditions in the modeling of fluvial erosion processes.
由于土地利用和环境脆弱性，河流侵蚀动态响应山坡上的土壤侵蚀和地表径流，其受到土壤、地质、地形和降雨率的制约。尽管巴西与河流侵蚀相关的问题日益增多，但关于高强度农业活动下源头集水区推移质输移的信息却很少。因此，本研究旨在描述巴西南部一个实验集水区的河流侵蚀过程和推移质动态，该集水区位于巴西南部高原边缘，代表了巴西南部大面积高环境脆弱性和高强度农业活动的地区。瓜尔达莫尔河流经一个源头集水区（18.5公里），地形起伏多山，土壤脆弱，高强度农业活动控制着下游细颗粒和粗颗粒沉积物的供应。在11次主要降雨径流事件期间，进行了监测，以测量流量、推移质输移率、沉积物粒径以及水力参数，如曼宁糙率系数值和粘性层厚度。根据沿水文过程线在不同水位和阶段进行的40次流量和推移质流量测量建立了水位流量关系曲线。此外，还对一段河流（砾石床）及其表层和次表层的粒度特征进行了描述。结果表明，输移模式不仅受水力参数的影响，还受其他因素的影响，包括连续事件之间的相互依存关系、装甲效应和滞后现象。这些因素与山坡上观测到的地表径流和侵蚀密切相关，地表径流和侵蚀分别决定了水流能量和砂粒部分的供应。本文对河流侵蚀过程建模中非平衡条件下的推移质输移动力学进行了讨论。
