Instituto de Pesquisas Hidráulicas (IPH), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.
Departamento de Engenharia Sanitária e Ambiental (DESA), Universidade Federal de Santa Maria (UFSM), Santa Maria, Brazil.
Environ Monit Assess. 2020 Oct 30;192(11):736. doi: 10.1007/s10661-020-08670-y.
Sediment yield in river catchments can cause siltation of reservoirs and channels, carries contaminants adhered to sediment particles, and represents water erosion at the catchment scale, leading to decreased agricultural productivity. Hydrological monitoring enables the understanding of overland flow and soil erosion dynamics. In this study, we analyzed whether the relationship between precipitation (P), water flow (Q), and suspended sediment concentration (SSC) during rainfall events shows the usefulness of hydrological and sedimentological monitoring in soil and water conservation projects to river catchments. We conducted a study in the Lajeado Ferreira catchment in southern Brazil. This catchment is characterized by high soil fragility and erosion rates because of relief and intense tobacco cultivation. The small size of the catchment (120 ha) allowed a better understanding of the processes that occurred between hillslope and watercourses. We analyzed 43 rainfall-runoff events (P-Q), and we selected characteristic variables of each event and related them to independent variables (climate, land use, and soil management) and their seasonality using regression techniques. We also conducted a hysteresis analysis to understand the behavior of SSC in relation to runoff. The results showed a high relation of sediment yield (SY) with maximum water flow of the event (Q), and linear regression models showed the best performance between characteristic variables. In addition, the seasonal variability of the land coverage presented greater influence on the SY than the precipitation itself.
河流流域的泥沙输出会导致水库和河道淤积，携带附着在泥沙颗粒上的污染物，并代表流域尺度的水蚀，导致农业生产力下降。水文监测可以了解地表径流和土壤侵蚀动态。在本研究中，我们分析了降雨事件期间降水（P）、水流（Q）和悬浮泥沙浓度（SSC）之间的关系是否表明水文和泥沙监测在水土保持项目中对河流流域的有用性。我们在巴西南部的拉杰多费雷拉流域进行了一项研究。由于地形和密集的烟草种植，该流域的土壤脆弱性和侵蚀率很高。流域面积小（120 公顷），可以更好地了解山坡和河道之间发生的过程。我们分析了 43 次降雨径流事件（P-Q），并选择了每个事件的特征变量，并使用回归技术将其与独立变量（气候、土地利用和土壤管理）及其季节性相关联。我们还进行了滞后分析，以了解 SSC 与径流之间的关系。结果表明，泥沙产量（SY）与事件的最大水流（Q）高度相关，特征变量之间的线性回归模型表现最佳。此外，土地覆盖的季节性变化对 SY 的影响大于降水本身。
