Abstract

The application of multivariate statistical analysis (MSA) in analyzing drainage basin morphometry, in conjunction with seismic events (focal mechanism) and associated tectonic influences, has been discussed less in the framework of existing geomorphometric studies. Hence, in this study, an integrated approach was designed combining the geomorphometric analysis with MSA, focal mechanism and associated structural lineaments (using a remote sensing and GIS framework) to address the role of active tectonism on the drainage network characteristics in Qorveh-Dehgolan basin located in western part of Iran (Kurdistan province). Eight watersheds were delineated from burnt ASTER DEM using SWAT model and categorized into high-altitude watersheds and low-altitude watersheds. Four-sets of the drainage network were extracted from satellite imageries (Landsat 7 and 8) over a period of 17 years (2000–2017) to monitor the temporal stream network behavior. Overall, nineteen morphometric parameters were calculated (and categorized into linear, aerial, and relief aspects) exhibiting significant changes in the drainage network from 2000 to 2017 (the stream order declined from 5th to 4th order). The higher-altitude watersheds showed various anomalies in the calculated indices (indicating the potential influence of tectonic activity), while the lower altitude watersheds did not exhibit any specific anomalies. In addition, higher concentration of longer lineaments was observed in areas where the relatively resistant, fractured bedrock lithology (meta-volcanic and meta-sedimentary rocks) provided favorable conditions for origin and propagation of the lineaments. Further analysis of focal mechanism solutions (FMS, beachball diagrams) showed that the study area is primarily influenced by moderate earthquake events (3 ≤ Mw ≤ 6) and is influenced by a complex fault mechanism (primarily normal faults and strike slip faults). The morphometric parameters were further subjected to the factor analysis (principal axis factoring using Varimax rotation transformation) resulting in derivation of “factor of basin magnitude”, “factor of steepness” and “factor of texture” as three principal factors impacting the drainage network. Finally, it was concluded that “factor of steepness” played a decisive role in defining hydrology of higher-altitude watersheds (an indication of tectonic influences in these watersheds) and thereby defining the overall hydrology of the study area as well. Overall, this study highlighted the significant role of the tectonic activity associated with structural lineaments and the seismic events in defining the nature and behavior of the drainage network and certain anomalies caused in the basin hydrology under these structural controls.

摘要

多变量统计分析 (MSA) 在分析流域形态测量中的应用，结合地震事件（震源机制）和相关的构造影响，在现有地貌测量研究的框架中讨论得较少。因此，在本研究中，设计了一种综合方法，将地貌计量分析与 MSA、震源机制和相关构造线（使用遥感和 GIS 框架）相结合，以解决活动构造对 Qorveh-Dehgolan 盆地排水管网特征的作用。位于伊朗西部（库尔德斯坦省）。使用 SWAT 模型从烧毁的 ASTER DEM 中划定了 8 个流域，并将其分为高海拔流域和低海拔流域。在 17 年（2000-2017 年）期间，从卫星图像（Landsat 7 和 8）中提取了四组排水管网，以监测时间流网行为。总体而言，计算了 19 个形态测量参数（并分为线性、空中和地形方面），显示出 2000 年至 2017 年排水网络的显着变化（河流顺序从第 5 次下降到第 4 次）。高海拔流域在计算指数中显示出各种异常（表明构造活动的潜在影响），而低海拔流域没有表现出任何特定的异常。此外，在相对抗性的区域观察到较高浓度的较长纹路，断裂的基岩岩性（变质火山岩和变质沉积岩）为线纹的起源和扩展提供了有利条件。对震源机制解（FMS，沙滩球图）的进一步分析表明，研究区主要受中度地震事件（3≤Mw≤6）的影响，并受到复杂断层机制（主要是正断层和走滑断层）的影响。进一步对形态参数进行因子分析（使用 Varimax 旋转变换的主轴因子分解），得出“盆地大小因子”、“陡度因子”和“纹理因子”三个影响排水管网的主要因素。最后，得出的结论是，“陡度因素”在定义高海拔流域的水文（表明这些流域的构造影响）方面发挥了决定性作用，从而也确定了研究区域的整体水文。总体而言，这项研究强调了与构造线和地震事件相关的构造活动在确定排水管网的性质和行为以及在这些构造控制下流域水文引起的某些异常方面的重要作用。