Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Emam Reza Street, Noor, P.O. Box: 46417-76489, Iran.
Soil Physics and Land Management Group, Wageningen University, Droevendaalsesteeg 4, 6708PB Wageningen, Netherlands; Civil, Surveying and Environmental Engineering, The University of Newcastle, Callaghan 2308, Australia.
Sci Total Environ. 2017 May 15;586:492-501. doi: 10.1016/j.scitotenv.2017.01.208. Epub 2017 Feb 13.
Fluvial dynamics in riverine borders can play an important role in political relationships between countries. Rivers move and evolve under the influence of natural processes and external drivers (e.g. land use change in river catchments). The Hirmand River is an important riverine border between Iran and Afghanistan. The present study shows the evolution and lateral shifting of the Hirmand River along the international border (25.6km) over a period of 6 decades (1955-2015). Seven data series of aerial photos, topographic maps and Landsat images were used to analyze land cover and channel changes in the study reach. The land cover has changed dramatically on both sides of the border during the last 6 decades, especially in the Afghan part. Overall, 49% of all land surface changed its cover type, especially the area of agriculture and residential land contributed to that, with an increase in surface area of about 4931ha and 561ha, respectively. On the other hand, the natural cover and water bodies decreased to 38% and 63%, respectively. The impact of these land use changes on the morphological evolution of Hirmand River was investigated in 5 sub-reaches. We found an average decrease of the active channel width of 53% during 60years and the average River Network Change Index for the whole study reach during 60years was -1.25m/year. Deposition and narrowing turned out to be the main processes occurring within the study reach. Furthermore, due to natural riverine processes the Hirmand River has moved towards Afghanistan (37m on average) and lateral shifting was found to be up to 1900m in some sections.
河流边界的河流动态在国家间的政治关系中起着重要作用。河流在自然过程和外部驱动力（如流域内土地利用变化）的影响下移动和演变。赫尔曼德河是伊朗和阿富汗之间重要的河流边界。本研究展示了赫尔曼德河在国际边界（25.6 公里）沿线的演变和侧向移动，时间跨度为 60 年（1955-2015 年）。本研究使用了 7 组航空照片、地形地图和 Landsat 图像数据序列，来分析研究河段的土地覆盖和河道变化。在过去的 60 年里，边界两侧的土地覆盖发生了巨大变化，特别是在阿富汗一侧。总体而言，49%的地表覆盖类型发生了变化，特别是农业和居住用地面积增加了约 4931 公顷和 561 公顷。另一方面，自然覆盖和水体面积分别减少到 38%和 63%。在 5 个亚河段研究了这些土地利用变化对赫尔曼德河形态演变的影响。我们发现，在 60 年期间，活跃河道宽度平均减少了 53%，整个研究河段的河流网络变化指数在 60 年期间平均为-1.25m/年。结果表明，沉积和变窄是研究河段内发生的主要过程。此外，由于自然河流过程，赫尔曼德河已经向阿富汗移动（平均 37 米），在一些河段发现侧向移动高达 1900 米。
