Many areas from the Mediterranean region are characterised by steep slope gradient, patchy vegetation cover and soil surface conditions prone to overland flow generation and sediment transport. This study evaluated the hydrological and sediment connectivity between sections (top, middle and bottom-channel) from three low pressure grazed hillslopes located under contrasted Mediterranean climatic conditions in southern Spain. The aim was performed by installing rain-gauge stations and opened-plots in order to register overland flow and sediment concentration from Feb-2008 to Jan-2010. The results indicated that: i) major volumes of overland flow and sediment transport occurred more frequently in the humid and semiarid; ii) the more frequent hydrological connectivity was observed between the middle and bottom-channel sections, though the major values of overland flow and sediment concentration were registered in the upper sections; iii) it was found very frequent those rainfall events in which all sections contributed with overland flow and sediment to the channel; iv) the factors controlling hydrological and sediment connectivity varied from one site to another depending on the rainfall regime and vegetation cover, though the soil surface conditions (rock fragment cover either embedded or not embedded, crusts, annual plants, among others) were found a key factor in all of them. In summary, the grazing activity, even being of low pressure, contributes to distance the hydrological and sediment connectivity from the response expected in the field sites, especially, in that of humid Mediterranean climate: more overland flow and less sediment concentration and, vice versa, when becomes arid.

中文翻译：

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低压力放牧对地中海气候条件（西班牙南部）下山坡上的水文和沉积物连通性的影响。

地中海地区的许多地区的特点是坡度陡峭、植被斑驳，土壤表面条件容易产生地表水流和沉积物迁移。本研究评估了西班牙南部地中海气候条件对比鲜明的三个低压放牧山坡部分（顶部、中部和底部通道）之间的水文和沉积物连通性。目的是通过安装雨量站和开放地块来实现 2008 年 2 月至 2010 年 1 月的地表径流和泥沙浓度。结果表明：i) 湿润和半干旱地区更频繁地发生大量的地表漫流和泥沙输移；ii) 在河道中段和底段之间观察到更频繁的水文连通性，虽然地表径流和泥沙浓度的主要值记录在上部；iii) 发现那些降雨事件非常频繁，其中所有部分都促成了地表水流和沉积物进入河道；iv) 控制水文和沉积物连通性的因素因降雨情况和植被覆盖而因地点而异，尽管发现土壤表面条件（嵌入或未嵌入的岩石碎片覆盖、地壳、一年生植物等）所有这些的关键因素。总之，放牧活动，即使是低压，也有助于使水文和沉积物连通性与野外现场预期的响应相距甚远，尤其是在潮湿的地中海气候中：更多的地表流量和更少的沉积物浓度，反之亦然,