摘要
马格达莱纳河是哥伦比亚安第斯山区的一个世界级的河流网络，该河流年产沙量约为150Mt，是全世界10大主要产沙河流之一。在本研究中，我们探讨主要自然因子和人类活动对马格达莱纳河流域产沙模式的影响，重建该区森林砍伐和农业活动时空模式，探讨土地利用变化与产沙趋势的关系。我们的研究结果表明，整个马格达莱纳河流域的产沙量可以用自然变量（包括径流量和最大河水流量）来解释。这两个因子解释了产沙量58％的变化。含沙率和土地利用的时间分析表明，在过去10～20年里流域侵蚀呈现增加的趋势。许多人类活动的影响，包括森林覆被在20年里减小了近40％．农业和牧场增加了65％、土壤保持差、开矿活动，以及城市化的加速，都促进了该地区域尺度上产沙量的增加。
The Magdalena River,a major fluvial system draining most of the Colombian Andes, is a world-class river,in the top 10 in terms of sediment load (≈150 MT/yr).In this study,we explore the major natural factors and anthropogenic influences behind the patterns in sediment yield on the Magdalena basin and reconstruct the spatial and temporal pattern of deforestation and agricultural intensification across the basin to test the relationships between land use change and trends in sediment yield.Our results show that sediment yield for the whole Magdalena catchment can be explained by natural variables,including runoff and maximum water discharge. These two estimators explain 58% of variance in sediment yield.Temporal analyses of sediment discharges and land use show that the extent of erosion within the catchment has increased over the last 10 to 20 years.Many anthropogenic influences,including a forest decrease by 40% in a 20-year period,an agriculture and pasture increase by 65%,poor soil conservation and mining practices,and increasing rates of urbanization,may have accounted for the overall increasing trends in sediment yield on a regional scale.
