Steegen A, Govers G, Takken I, Nachtergaele J, Poesen J, Merckx R
Lab for Experimental Geomorphology, KU Leuven, Belgium.
J Environ Qual. 2001 Jul-Aug;30(4):1249-58. doi: 10.2134/jeq2001.3041249x.
Sediment and total phosphorus (TP) export vary through space and time. This study was conducted to determine the factors controlling sediment and TP export in two agricultural catchments situated in the Belgian Loess Belt. At the outlet of these catchments runoff discharge was continuously measured and suspended sediment samples were taken during rainfall events. Within the catchments vegetation type and cover, soil surface parameters, erosion features, sediment pathways, and rainfall characteristics were monitored. Total P content and sediment characteristics such as clay, organic carbon, and suspended sediment concentration were correlated. Total sediment and TP export differ significantly between the monitored catchments. Much of the difference is due to the occurrence of an extreme event in one catchment and the morphology and spatial organization of land use in the catchments. In one catchment, the direct connection between erosive areas and the catchment outlet by means of a road system contributed to a high sediment delivery ratio (SDR) at the outlet. In the other catchment, the presence of a wide valley in the center of the catchment caused sediment deposition. Vegetation also had an effect on sediment production and deposition. Thus, many factors control sediment and TP export from small agricultural catchments; some of these factors are related to the physical catchment characteristics such as morphology and landscape structure and are (semi)permanent, while others, such as vegetation cover and land use, are time dependent.
沉积物和总磷（TP）的输出随空间和时间而变化。本研究旨在确定比利时黄土带两个农业流域中控制沉积物和TP输出的因素。在这些流域的出口处，连续测量径流流量，并在降雨事件期间采集悬浮沉积物样本。在流域内，对植被类型和覆盖度、土壤表面参数、侵蚀特征、沉积物路径和降雨特征进行了监测。将总磷含量与沉积物特征（如粘土、有机碳和悬浮沉积物浓度）进行了关联分析。监测的流域之间，总沉积物和TP输出存在显著差异。大部分差异是由于一个流域发生了极端事件以及流域内土地利用的形态和空间组织造成的。在一个流域中，侵蚀区域通过道路系统与流域出口直接相连，导致出口处的沉积物输送率（SDR）较高。在另一个流域中，流域中心宽阔山谷的存在导致了沉积物的沉积。植被也对沉积物的产生和沉积有影响。因此，许多因素控制着小型农业流域的沉积物和TP输出；其中一些因素与流域的物理特征（如形态和景观结构）有关，是（半）永久性的，而其他因素，如植被覆盖和土地利用，则随时间变化。
