Institute of Geographical Sciences, Freie Universität Berlin, Berlin, Germany.
Department of Geography, Physical Geography, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
PLoS One. 2021 Feb 5;16(2):e0245248. doi: 10.1371/journal.pone.0245248. eCollection 2021.
The cost of human movement, whether expressed in time, effort, or distance, is a function of natural and human related variables. At the same time, human movement itself, whether on land, air or sea, causes environmental cost. We are looking into the long-term environmental relationship of this interplay. Gullies-linear landforms, which dissect the landscape-are considered to be a cost for human movement, as they can form unpassable barriers destroying present path networks. On the other hand, human movement creates pathways, which flatten the surface and decrease the water permeability potential. This process results in runoff generation and possibly gully erosion. Accordingly, the spatial relationship between pathways and gullies is investigated. In the Tigray region of the Northern Ethiopian Highlands, gullies and pathways were mapped using remote sensing data. Frequency Ratio was used for assessing pathways as a variable affecting the location of gullies while Least Cost Paths were tested to evaluate the possible constraining impact gullies have on mobility. Based on these results, it is concluded that a positive feedback exists between the cost of human movement and gully erosion. We further discuss possible effects gullies may have had on trade, territory, and political affairs in Tigray. Consequently, we suggest that movement cost and gullying may not only hold strictly environmental or movement-related implications, but also socio-cultural ones.
人类活动的成本，无论是在时间、精力还是距离上的表现，都是自然和人为相关变量的函数。与此同时，人类自身的活动，无论是在陆地、空中还是海上，都会造成环境成本。我们正在研究这种相互作用的长期环境关系。冲沟——线性地貌，它们割裂了景观——被认为是人类活动的成本，因为它们可能形成不可逾越的障碍，破坏现有的路径网络。另一方面，人类活动会形成路径，使表面变平，降低水渗透的潜力。这一过程会导致径流的产生，并可能引发冲沟侵蚀。因此，研究了路径和冲沟之间的空间关系。在埃塞俄比亚北部高地的提格雷地区，使用遥感数据绘制了冲沟和路径图。频率比被用来评估路径作为一个影响冲沟位置的变量，而最小成本路径则被用来评估冲沟对流动性的可能限制影响。根据这些结果，可以得出结论，人类活动成本和冲沟侵蚀之间存在正反馈。我们进一步讨论了冲沟可能对提格雷的贸易、领土和政治事务产生的影响。因此，我们认为，移动成本和冲沟侵蚀不仅可能具有严格的环境或移动相关影响，还可能具有社会文化影响。
