科研之友
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摘要
The distribution, thickness and composition of the floodplain sediments in the valleys of the Gelbach (Lower Westerwald) and Grosse Nister (Upper Westerwald) depend on the occurrence of loessic periglacial cover beds in their catchments as well as on historical land use. The budget of floodplain sedimentation was derived from a study of the floodloams underlying the monastery garden of Marienstatt, a village in the Grosse Nister valley. From the study of two occupation levels, pottery shards and radiocarbon dating, 55% of the floodloam can be attributed to the Modern period (younger than c. ad 1450). From the radiocarbon age of a charcoal fragment extracted from the base of the floodloam at another site in the Nister valley, it can be concluded that the floodloams were almost exclusively deposited by human impact since the time of High Medieval expansion of settlement into the Uplands. The fine-grained loamy sediments blanket a rather irregular floodplain of channels and gravel bars. Similar results as to the age of the floodplain sediments were obtained from radiocarbon datings obtained for the Gelbach valley. Floodloam sediment budgets of the rivers and their tributaries have been calculated for the Grosse Nister and the Gelbach valleys of the Westerwald and, for including a catchment of higher sedimentation, the Aar River of the Taunus Mountains, followed by a comparative analysis of the results in relation to potential erosion areas in the catchment. The amount of areal soil erosion in upland areas in historical times has been found to be considerably higher than generally assumed. Average amounts of anthropogenic soil erosion could thus be calculated from the floodloam deposition: 1677.4 t/ha for the Aar catchment, 1084.5 t/ha for the Gelbach catchment, and 841.8 t/ha for that of the Nister. The calculated total amount of soil erosion is then subdivided by periods.
- 出版日期2011-5
