Study On Lineaments Extraction And Active Tectonic Geomorphology In The Qianhe Basin Based On Multiple Remote Sensing Data

The active tectonics and landform evolution of the intersection between the southwest margin of Ordos and the northeast margin of Qinghai-Tibet Plateau are the key areas for regional landslide and seismic hazard research,however,traditional field geological measurements cannot quantify the active tectonic activity.Fluvial geomorphology can respond to regional differential tectonic uplift in terms of channel slope and width,and is characterized in remote sensing data.Recently,due to the advantages of all-day,all-weather,easily access,and high resolution,remote sensing technology has gradually broken through the deficiencies of traditional geological field survey,such as difficult to access,dengeous,and impossible to quantify.The analysis of superficial geological phenomena by means of remote sensi ng to reveal deep geophysical structures has become a major trend in earth science.In view of this,this paper addresses the difficulties that geological structures in loess-covered areas are covered by loess and the evolution of regional tectonic geomorphology cannot be quantified,considering the characteristics of multiple remote sensing data,and combining remote sensing,mathematical geology,computer science and fluid mechanics,designs and implements a lineament and river width extraction algorithm based on multiple remote sensing data,and analyzes the longitudinal river profile and cross-section profile in response to regional differential tectonic uplift.The following sections are the core material and findings:(1)Study on the extraction of geological lineaments in loess covered area based on remote sensing dataBased on the linear characteristics of geological lineaments on multiple remote sensing images,“An extraction algorithm of geological lineaments based on Tensor Voting coupled Hough Transform”is proposed,and the correctness of this algorithm is verified by comparison with other algorithms such as STA and PCI,indicating that our algorithm has strong spatial continuity and better coincidence with tectonics.The lineaments in the Qianhe Basin mainly show characteristics such as short and dense,concentrated around large faults;their main direction is NW-SE and followed by NE-SW;by analyzing the fractal dimension and multifractal spectrum of lineaments here,the results indicate that the faults in Qianhe Basin are medium-sized faults with complex structure and unstable development.Although they have high intensity activity,the activity is infrequent.(2)Study on the extraction of river longitudinal profile features of the Qianhe Basin based on multiple remote sensing dataThe influence of vertical accuracy of multiple remote sensing data(SRTM1,ASTER-GDEM and DEM extracted by Zi Yuan-3 stereo images)in understanding the transient fluvial channel parameters is explored,and the feasibility and shortcomings of ZY3-DEM in tectonic geomorphology are verified.The pattern and spatial distribution of knickpoints,and normalized steepness index(k_sn)on the river longitudinal profile are also extracted,revealing that the knickpoints in Qianhe Basin is the result of differential uplift of regional tectonics,and only responding to the active tectonics.Thus,the uplift rate gradually decreases from northwest to southeast,and the uplift of the southern margin is greater than that of the northern margin;then the retreate rate of slope-break knickpoints in the horizontal migration is investigated,with a range of 0.3-27.3 mm/yr,the knickpoint recession triggered by base-level fall as a result of active faulting is lower than sea-level fall;combing the fault linkage and the displacement-length model,the potential earthquake magnitudes before and after the fault linkage in the Qianhe Basin are predicted,with a magnitude of 6.3-6.7 and6.8-7.0,respectively.(3)Study on the channel cross-section profile of the Qianhe Basin based on multiple remote sensing dataAn algorithm of channel width extraction based on remote sensing images and DEM data is proposed,which is more accurate and closer to the field measurement results(R²=0.92)and reduces the human intervention;then the channel width,drainage area-channel width index(b?)and normalized wideness index(kwn)are used to explore the response to the differential tectonic uplift of the Qianhe Basin:the increased rate of tectonic uplift in the southern margin of the Qianhe Bbasin resulted in lower channel width,b?and k_wn than in the northern margin where the lower uplift rate.Moreover,the adjustment of channel width and steepness on the distribution of unit stream power(?)and boundary shear stress(?_b)along strike was also discussed,revealing that the main cause of the trend“increasing and then decreasing”.The final vertical activity rate of TGF was 1.3-1.4 times that of QMF,with a range of 0.033-0.059 mm/yr.