Geomorphic Indices Research Articles

Morphotectonic analysis of the Sali River basin, Bankura district, West Bengal

Morphotectonic analysis of a drainage system is widely applied in evaluating the morphological evolution of a region in response to tectonic deformation as reflected by structural and morphometric parameters. Essentially, the combination of lithological, tectonic, and climate factors lead the development and the evolution of a drainage system regardless of the general geological setting of a region. The Sali River is developed in the westernmost part of the shelf zone of the Bengal Basin and adjusts its course depending on the underlying geological structure, climatic effects, and tectonic activities. In order to identify the tectonic activity of the study area, morphotectonic and geomorphic analyses have been carried out by performing a tectonic lineaments analysis and by evaluating different geomorphic indices, like hypsometric integral (Hi), elongation ratio (Re), stream length-gradient index (SL), river profile, ratio of valley floor width to valley height (Vf), stream sinuosity, etc. The structural and morphological (e.g., incised valleys and hanging paleochannels) features were able to hypothesize the influence of active tectonics on the Quaternary evolution of the landscape. On the basis of morphotectonic analysis, an attempt has been made to trace out the plausible phases of the geomorphic evolution of the Sali basin by using remote sensing and GIS techniques. Analysis of the all morphometric and geomorphic indices revealed that the upper catchment tectonic activity plays an important role in the development of watershed hydrology, whereas the basin that is located in lower altitude (where Pleistocene to Holocene deposits crop out) are affected by depositional and neotectonic activity.

Drainage Characteristics of Tectonically Active Area: An Example from Mawar Basin, Jammu and Kashmir, India

Abstract Geomorphic and neo tectonic studies have been carried out for the first time in Mawar basin of the Kashmir valley. On the basis of field investigations and geomorphic data derived from toposheets and satellite imageries, with the help of Arc GIS (10.3) and Global Mapper (18) the relationship between morphology and tectonics has been investigated in Mawar basin, which lies to the northwest of Kashmir valley. The morphotectonic aspects like mountain front sinuosity (Smf), hypsometric integral (Hi), have been studied to relate the tectonic forces with erosive power and identify the areas where field investigations are required. The field interpretation indicates that the landforms of the area are structurally controlled and mainly consist of tectonic linear, parallel striking ridges and valleys. The course of Mawar is mostly controlled by the Mawar fault striking east–west and local structures present in the area. General morphometric parameters like assymetry factor (Af), transverse topography symmetry (T), stream length gradient (SL) and valley floor width to height ratio (Vf) have been computed to draw the conclusion of tectonic activity on the drainage. The Af and T suggest that the basin has shifted to the right side and the Mawar river has shifted to the left side when facing downstream. The SL values indicate that the river has fluctuations in gradient/knickpoints at 6.8, 10 and 18 km from the source. However the Vf values infer the basin has deeply incised V-shaped valleys. All the quantified geomorphic indices and their interrelationship with the geomorphology are useful in comparing different drainage basins in terms of tectonic character and are helpful in delineating the areas where more detailed works will be fruitful. The results of computed geomorphic indices, geomorphology and the structures present in the Karewas (Plio Pleistocene) deposits inferred that the basin has shown activity in Pleistocene period, suggesting the basin is tectonically active.

Geomorphic evolution and neotectonics of the Qianhe River Basin on the southwest margin of the Ordos Block, North China

The Qianhe River Basin is located at the convergence zone of the northeastern margin of the Tibetan Plateau (NETP), the Ordos Block and the Qinling Mountains. A tectonic geomorphology study of the Qianhe River is significant for providing a deeper understanding of the tectonic transition between the NETP and the Ordos Block and the dynamic relationship of these three tectonic units. Based on Advanced Spaceborne Thermal Emission and Reflection global digital elevation model (ASTER-GDEM) data and geographic information system (GIS) techniques, four tectonic geomorphic indices, the hypsometric integral (HI), stream length-gradient (SL), drainage basin asymmetry (AF), and drainage basin shape (BS), were calculated and analyzed. Geologic evidence from field surveys, deformation measurements, and fault slip rate estimates was also obtained to further discuss the tectonic activity and tectonic geomorphic evolution model. Through analytical comparisons, we proposed that the variations in the applied geomorphic index values were not significantly affected by climate and lithology but indicated variations in related tectonic activity. The geomorphic index value analysis suggested relatively strong tectonic activity in Liupanshan Mountain and Longshan Mountain and northwestward tectonic tilting of the southwest margin of the Ordos Block. The actual mechanisms responsible for the observed variations in the Qianhe River Basin are the rapid uplift and northeastward extrusion of the Qinghai-Tibetan Plateau and the local tilting uplift of the southwestern Ordos Block.

Evaluation of neotectonic variability along major Himalayan thrusts within the Kali River basin using geomorphic markers, Central Kumaun Himalaya, India

We have analysed the geomorphic signatures in aggregation with the geomorphic indices with respect to hinterland and foreland neotectonic variability across the major Himalayan thrust system along the Kali River valley of eastern Kumaun Himalaya. The valley floor morphology in the vicinity of the major thrust gave rise to the accommodation space for the aggradation of the recent fluvial sediments. For a longitudinal distance of 212 km between the South Tibet Detachment (STD) and Himalayan Frontal Thrust (HFT), the valley has preserved significant aggradational landforms. These landforms have been physically examined to explain the spatial and temporal variability in phases of aggradation/incision in response to the tectonic activity during the late Quaternary. Fossil valleys and associated epigenetic gorges, cut‐and‐fill terraces with thick alluvial cover, debris‐flow terraces, bedrock strath terraces, and alluvial fan terraces are the significant aggradational landforms observed within the valley. They provide signatures of tectonic activity and past climatic records. We have analysed various geomorphic indices, namely, stream‐gradient index (SL), steepness index (Ks), hypsometric curve and index (HI), and asymmetric factor (AF) to map the spatial variability in tectonic processes across the major thrusts. The channel morphology (depth and width) of a river becomes adjusted in geological time because of long‐term tectonic and erosional processes. However, the channel geometry and deviations can be highly adjustable in a tectonically disturbed mountainous region. The deviations along the river course can be attributed to active tectonic movement along thrusts/faults or because of erosion/sedimentation processes. We applied a novel method called the river Gradient Length Anomaly (GLA) for 37 subbasins of the Kali River to deduce active deformation (uplift/subsidence) corresponding to the increased sedimentation and erosional rates, both from the upstream and downstream parts of the thrusted blocks, from where river flows through. The results of basin‐wise morphometric indices were corroborated with GLA anomaly and field observations, which suggests that the area has undergone active deformation between the Main Central Thrust (MCT) and Himalayan Frontal Thrust (HFT), which is attributed to the regional compression. The results of geomorphic and morphometric data are validated with the focal mechanisms of moderate earthquakes. The geomorphic analysis suggests that the hinterland part of eastern Kumaun is more active than the foreland region.

Longitudinal profiles and geomorphic indices analysis on tectonic evidence of fluvial form, process and landform deformation of Eastern Himalayan Rivers, India

ABSTRACTThe drainage pattern and the morphology of the piedmont zone of the Himalayas are clear indicators of the active orogenic belt of most recent origin formed by the collision of Indian and Eurasian plate. The foothills of the Himalayas in West Bengal are zones of active tectonics drained by the rivers belonging to the Brahmaputra system. The present study is conducted for the left bank tributaries and sub-tributaries of Tista which bear the imprint of active tectonics of the region as they lie in the zone of Himalayan Frontal Fault, the most active thrust belt of Himalayas. Data and subsequent field experiences which showed that the region is constantly acted upon by recent diastrophism. Various tectonic indices were calculated to evaluate the evidence of tectonism. This include hypsometric integral (HI), fractal dimension (FD), basin asymmetry factor (AF), basin shape index (Bs), stream-length gradient (SL), mountain front sinuosity (Smf) and valley-floor width to valley height ratio (Vf). The results of these indices are used to prepare an index of active tectonics with three classes which is represented in a map. Then the field evidences of deformed landscape are matched with the areas showing high tectonic index values.

Asymmetrical river valleys and their tectonic significance in the Maxianshan area, NE Tibetan Plateau

The geometry of river networks is particularly sensitive to active tectonic deformation. Morphotectonic analyses conducted using geomorphic indices and numerical models are useful methods with which to identify such deformation. The northeastern (NE) margin of the Tibetan Plateau is characterized by active tectonics, easily erodible bedrock and well-developed valleys, and is thus an ideal region for studying the effects of tectonics on the landscape evolution. Here we firstly identify the systemic asymmetrical valleys in the Maxianshan area, NE Tibetan Plateau. To quantitatively analyze the asymmetrical characteristics of these valleys identified in the southern Maxianshan, 33 parallel streams were investigated by using two drainage basin analytical techniques, namely, the transverse topographic symmetry factor (T) and asymmetry factor (AF). Our results show that the mean T value is 0.14 (magnitude) and 319.08° (direction) and the majority of the AF results are <50, indicating a north-westward migration. In addition, we suggest that this north-westward migration could be caused by the variable rates of uplift experienced across the Maxianshan area, an assertion which is also supported by the inversion results of GPS measurements and earthquake distributions. In contrast to previous studies, we conclude that the variable rates of uplift are probably caused by the distribution of stress within the four quadrants of a strike-slip fault. This mechanism is validated by using the landscape evolution model SIGNUM and studying examples from other strike-slip fault zones, such as the Haiyuan Fault Zone on the NE Tibetan Plateau, Qujiang Fault Zone and Daqing Fault Zone on the southeastern (SE) Tibetan Plateau and Tieluzi Fault Zone in central China. By using quantitative methods and modeling, our study appears to demonstrate that asymmetrical valleys are important geomorphic characteristics of strike-slip faults.

Dynamic and geomorphic characterizations of the Mocoa debris flow (March 31, 2017, Putumayo Department, southern Colombia)

On the night of March 31, 2017, a rainfall-induced landslide event with more than 600 shallow landslides was triggered in Mocoa (Putumayo Department, southern Colombia). These landslides and the subsequent Mocoa Debris Flow (MDF) event caused, according to data published from the Unidad Nacional para la Gestion del Riesgo de Desastres (UNGRD, disaster risk management government agency), a catastrophic aftermath where 333 people were killed (including at least 118 children), 398 people were injured, and 76 people are still missing. In order to unravel the kinematic aspects of the MDF formation and the geomorphic setting which conditioned debris flow and landslide formation, high-resolution drone and satellite imagery, geomorphic indices, landslide inventory, and rainfall data from the event were analyzed. Flow discharge and velocity calculations associated to the MDF were calculated using three different methodologies which showed that the flow acquired a volume of ~ 2.6 × 106 m3 and an average velocity of 8–12 m/s, while the landslides developed in the Taruca, Taruquita, Mulato, and Sangoyaco basins contributed an estimated volume of about 298,000 m3. A landslide volume of about 3.44 × 106 m3 of material was calculated, from which less than 10% feed the MDF. Heavy rainfall and antecedent rainfalls were the triggering factors associated to shallow landslides developed on granitic rocks from the Mocoa monzogranite. Mass movements developed in residual soils from sedimentary rocks are more related to poor vegetation cover and intense anthropic activity such as extensive farming and deforestation. The recent activity of La Tebaida–Mocoa Fault and exhumation of the Mocoa monzogranite are considered as the main contributors to hillslope instability and landslide susceptibility. An active tectonic mountain front, steep slopes, and high drainage gradients are common at the study basins and are the key features controlling erosion and sedimentation rates. In this document, a brief introduction to the climatic, geological, and geomorphological characteristics of the involved basins and kinematic behavior of the MDF are presented.

Evaluation of the Relative Tectonic Activity of the Adıyaman fault within the Arabian-Anatolian.

The left-lateral strike-slip Adiyaman fault is located in eastern Turkey within the plate boundary deformation zone between Arabia and Anatolia. The Adiyaman fault is a major splay from the East Anatolian Fault (EAF), one of the most important tectonic structures in the Eastern Mediterranean region. These faults are consequence of the collision between the Arabian and Anatolian plates and the resulting westward tectonic escape of Anatolia. Although the EAF has been intensively studied since its discovery in the late 1960s, little is known about the Adiyaman fault and its tectonic activity. In this study, we extract geomorphic indices including mountain-front sinuosity (S mf ), valley floor width-to-height ratio (V f ), stream length-gradient (S L ), catchment Asymmetry Factor (AF) and hypsometric integrals and curves (HI and HC) to evaluate the relative tectonic activity of the Adiyaman fault. These three geomorphic indices (AF, HI, and HC) are averaged to define an index for Relative Tectonic Activity (RTA) that allows the Adiyaman fault to be divided into categories of low, moderate and high RTA. The results confirm that the Adiyaman fault is an active fault with high to moderate Quaternary tectonic activity. However, this fault is of minor importance on accommodating plate boundary deformation, as evidenced by the recent crustal motions determined by GPS studies. Nevertheless, it is worthwhile to note that the Adiyaman fault still poses a significant seismic hazard for the region despite its relatively moderate tectonic activity.

Geomorphic Indices of Tectonic Activity Through the Analysis of the Drainage Systems in Pera Magroon Anticline, Northeastern Iraq

The study area (Pera Magroon) is located within Kurdistan Region, Sulaimaniyah Governorate, north and northwest of Sulaimaniyah city northeastern Iraq. Arc GIS, hydro tool is used to extract the drainage network in the area under study by using digital elevation models (DEM). The study area is covered by dendritic and parallel drainage patterns and divided into twenty sub-basins. Three geomorphic indices, Mountain-front sinuosity (Smf), Stream-gradient index (SL) and Valley floor width-valley height ratio (Vƒ) were calculated for sub- basins. Through averaging these three indices, we obtained index of active tectonics (IAT). The values of the index were divided into classes to define the degree of active tectonics. Therefore, relative tectonic activity is calculated and their values are classified and analyzed in three groups. The sub-basins were identified as very high, high and moderate levels..

Evaluate Tectonic Activity of Tehran City (Iran) Based on Geomorphic Indices, Field Investigation and Remote Sensing Study

Active tectonics in the south part of Alborz Mountain (Iran) has greatly influenced the drainage system and geomorphic expressions. The metropolis of Tehran is located at the southern foothills of the Alborz Mountains at the abrupt topographic boundary between the mountain range and the northern border of the central Kavir Desert. The presence of active faults and tectonic activity, threatens the area and shows the vulnerability of this Tehran city. So the evaluation of active tectonics of Tehran City is necessary because of vast human activity, which has hidden geomorphic feature. Active tectonics of Tehran City was evaluated by using Digital elevation model (DEM) derived drainage network and three geomorphic indices basin (asymmetry factor (AF), basin shape index (Bs) and mountain front sinuosity (Smf)). The average of the three measured geomorphic indices was used to evaluate the distribution of relative tectonic activity in the study area. Furthermore to overcome some inevitable error in this method, field investigation was carried out also remote sense was studied, and finally the obtained results were compared with existing seismic data. The result confirms that the East South, East North and West North Tehran have high rate of relative tectonic activity (RTA) respectively.

Index of Active Tectonic Assessment: Quantitative-based Geomorphometric and Morphotectonic Analysis at Way Belu Drainage Basin, Lampung Province, Indonesia

The occurrence of subduction zones caused by the collision between the Eurasian-Western Indonesia Plate due to an increase tectonic, volcanic and magmatic activities along Sumatra Island. This study covers the area of Way Belu Drainage Basin, located near Bandar Lampung City, Lampung Province, southern part of Sumatra, Indonesia. The area composes of a complex geological structure as the result of tectonic activities. In this study, geomorphic indices assessment such as morphometric and morphotectonic quantitative analysis are undertaken to identify the Index of Active Tectonics (IAT). The morphometric analysis uses Drainage density (Dd) and Ratio of bifurcation (Rb). The value of Dd respectively from 1.45 to 4.05, Rb from 2 to 10. While the morphotectonic analysis uses basin shape index (Bs), valley floor width-valley height ratio (Vf), and asymmetry factor (AF). The value of Bs from 1.27 to 6.25, Vf from 0.16 to 3.30, and AF from 22.73 to 83.77 in ranges which is derived average IAT value is 2.20. It may considered that at the Way Belu Drainage Basin has moderate to high tectonic activity. From the joint measurement results on the fracture zone express that the main pattern of faults has trend NWW-SSE, NE-SW, NNE-SSW, NW-SE, and W-E directions. Furthermore, based on the combination of the quantitative geomorphology indices assessment which is supported by remote sensing and field assessment shows that those features closely related to the Semangko Fault System with the NNW-SSE fault trend parallel to its fault.

Neotectonics in the South American passive margin: Evidence of Late Quaternary uplifting in the northern Paraiba Basin (NE Brazil)

The relief evolution of several areas of northeastern Brazil has been increasingly related to tectonic events. This is the case for the Paraíba Basin, where an abundance of faults and folds were recorded in Neogene and even Late Pleistocene-Holocene deposits. We tested whether dome-like morphologies in the northern sector of this basin, where geological exposures are scarce, were also formed by tectonic deformation. The work combined limited geological data with qualitative and quantitative analyses of the relief applying the 1 arc-second digital elevation model provided by the Shuttle Radar Topography Mission. The geomorphic indices of basin asymmetry factor (AF), swath topographic profiles, enhanced transverse hypsometry index (THi*) and normalized river long-profiles were used for validating a neotectonic origin for the dome-like morphologies. This interpretation was also supported by other morphological evidence of the dome relief, including: recurving channels featured in radial to recurved trellis patterns; tectonically-controlled drainage sub-basins; high relative relief values related to increased fluvial incision; and anomalous river long-profiles indicative of ungraded rivers. The domic structures were attributed to fault- and fold-related strike-slip deformation during the late Quaternary. This record supports the proposal that the South American passive margin remained under tectonic stress long after the main rifting in the late Jurassic-early Cretaceous.

Tectono-climatic influence on landscape changes in the glaciated Durung Drung basin, Zanskar Himalaya, India: A geospatial approach

This study aims at assessing the tectonic and climatic responses to landscape changes transpired in the Durung Drung basin in the Zanskar Himalaya. We used relevant geomorphic indices interpreted from ASTER DEM satellite data and supplemented by the field observations to decipher active tectonics and resultant changes in the landscape. A N-S trending fault in the north of the basin was studied with the help of basin geometry which includes relative parameter, length area relation, form factor, shape factor ratio, elongation ratio, circulatory ratio, compactness coefficient and morphotectonic indices (e.g., drainage basin asymmetry, mountain front sinuosity, hypsometric integral, topographic symmetric factor) to comprehend the geomorphic signatures of the active tectonics. The geomorphic indices indicate upliftment and tilting of the basin. The data on mountain front index and hypsometric integral reveal the uplift and high relief. We propose that the western side of the basin is tectonically more active than eastern side, suggesting active upliftment. The convex nature of hypsometric curve and strongly elongated circulatory ratio reflect competing role of deformation by tectonics. The results of mountain front index and hypsometric integral reveal high relief and uplift. Overall deglaciation of 12.91% was observed in the basin. Analysis of the meteorological data for the last century (1901–2017) indicate that increase in minimum and maximum temperature coupled with increase in liquid precipitation are probably the main drivers of glacier depletion. We conclude that the drainage system of this basin is structurally controlled and overall landscape change is significantly influenced by the ongoing perturbations in the climate system.

Topographic Loads Modified by Fluvial Incision Impact Fault Activity in the Longmenshan Thrust Belt, Eastern Margin of the Tibetan Plateau

AbstractWhether external or internal forces of the Earth control the behaviors of upper‐crustal faults in a fold‐and‐thrust belt has been debated for decades. The Longmenshan thrust belt (LTB) along the eastern margin of the Tibetan Plateau may provide insights into such a debate, as the central segment of the LTB has relatively uniform shortening strains yet various fluvial incision capability along the strike. This tectonic setting enables a better assessment of the effects of external forces on fault activity. We analyzed the variations of topography, fluvial incision intensity, coseismic slips, and coseismic landslides along the central LTB. The Longmen subsegment in the northern half has higher elevation and lower fluvial incision intensity than the Hongkou subsegment in the south. We calculated the topographic stresses on the faults ruptured during the 2008 Wenchuan earthquake and found topographic introduced normal stress increase may explain the coseismic slip partitioning onto two subfaults along the Longmen subsegment. Our results indicate that fluvial incision may have produced the along‐strike variations of the topography, which may further produce the different rupture behavior. In addition, the mean hillslope angle along the central LTB appeared to be at the critical condition prior to the 2008 Wenchuan earthquake and reduced significantly by the earthquake, indicating that geomorphic indices may vary with different stages in an earthquake cycle. Therefore, scrutinizing the mean hillslope angle and other geomorphic indices may help identify potential seismic hazards in an active fault system.

Geomorphic evidence of unrecognized Qinghai Nanshan fault in the Gonghe Basin, northeastern Tibetan Plateau

The Qinghai Nanshan is located interior of northeastern Tibetan Plateau, extending W-E trending for 200 km between the Ela Shan and Riyue Shan, constituting the northern boundary of the Gonghe Basin. Qinghai Nanshan is very important to understand the Qinghai lake Basin-Gonghe Basin landscape evolution process, and it also provides a clue to understand the deformation of northeastern Tibetan Plateau. Our study focuses on identifying the unrecognized segment of the Qinghai Nanshan fault along the Gonghe Basin by applying river longitudinal profiles, and geomorphic indices such as stream length (SL) gradient index and mountain front sinuosity (Smf), as well as combining the field investigation. The results show that the anomalies of river longitudinal profiles in their upper reach may result from lithological contact, whereas the pronounced convex and deflection that occurred especially in the mid-reach are most likely related to recent tectonic activities caused by the Qinghai Nanshan thrust fault. Moreover, SL values are in agreement with the anomalies shown by the longitudinal profiles. Combining the results of geomorphic indices and topography analysis, as well as the field investigation, we project the distribution of the Qinghai Nanshan fault and discussed the tectonic implications. The listric Qinghai Nanshan thrust fault and the influences from the Elashan and Riyueshan dextral strike-slip faults are controlling factors for landscape of the Qinghai Nanshan.

The role of intraplate strike-slip faults in shaping the surrounding morphology: The Ovacık Fault (eastern Turkey) as a case study

Although the westward extrusion of the Anatolian Block is mainly compensated along its boundary faults, the North Anatolian and the East Anatolian shear zones, it is internally deformed in a dominant manner by some strike-slip faults as well. To obtain a better understanding about this intraplate deformation of the Anatolian Block, we investigate the tectonic geomorphology of the Ovacık Fault (OF), which is the northeastern member of the Malatya-Ovacık Fault Zone (MOFZ). Further, we apply the most common geomorphic indices, such as the hypsometric curve and integral, longitudinal channel profiles, channel steepness and concavity, mountain front sinuosity, and valley height-width ratio to characterise and quantify the deformation along the OF and the surrounding region where the regional morphology is shaped with the joint effect of palaeo- and neotectonics and other morphological factors such as palaeoglacial processes. The highest hypsometric integral, steepness and concavity values are generally observed along the northeastern strand of the OF (the Munzur Mountains) and the Kemaliye Region. Further, we interpret that high HI and steepness values indicate a regional tectonic uplift because of either a change in fault geometry, which gives rise to the vertical component on the OF, or a regional high convergence zone. Furthermore, this study gives the first calculation of vertical uplift in the northern margin of the Ovacık Basin (OB) as at least 0.5 mm/y for long term deformation history. Thus, our results exhibit that the OF is one of the intraplate strike-slip faults of the Anatolian Block.

Active tectonics analysis of the Kalmard fault zone, Central Iran

Central-East Iran has numerous active Quaternary faults. This paper focuses on the analysis of geomorphic and structural characteristics of the Kalmard fault zone, including major NE–SW striking fault segments that cuts across the basement and the sedimentary cover in the Ozbak-Kuh area of Central-East Iran. Because of the absence of definite earthquakes through the Kalmard fault zone in contrast to other parts of Central Iran, we used morphotectonic methods in combination of structural studies to evaluate active tectonics of this area. Detailed structural assessment of satellite images and analysis of geomorphic indices, together with field surveys allowed us to evaluate the recent tectonic activity and support a Quaternary age for it. We used six morphometric indices including the stream-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), valley floor width–valley height ratio (Vf), drainage basin shape (Bs), and mountain-front sinuosity (Smf). We combined these indices to yield the relative active tectonics index (Iat). Based on Iat values, the study area includes class 1 (very high activity), class 2 (high), class 3 (moderate), and class 4 (low). Also the normalized steepness index (Ksn) represents a significant pattern of high values in the eastern and southeastern parts of the study area which correspond with high values of Iat index. The output is consistent with both landforms and structures observed during the field work. In particular, the high relative tectonic activity (classes 1 and 2) largely corresponds to F1 (the eastern segment of the Kalmard Fault Zone) in the Ozbak-Kuh area, while the moderate class of tectonic activity caracterizes F2 (the western segment of the Kalmarad Fault Zone). The older geological structures in the middle part of the area show the lowest relative tectonic activity. The results of this study indicate that the Kalmard fault zone is one of the major Quaternary fault zones of Central-East Iran which is potentially active.

Treatise on the tectonic geomorphology of active faults: The significance of using a universal digital elevation model

This study presents the importance of the accuracy of six digital elevation models (DEMs), in the calculation of the geomorphic indices and the classification of an active fault in the Gulf of Corinth, Greece. Four of the DEMs used are based on public and global satellite imageries, the SRTM90, SRTM30, ASTER and ALOS. The other two are national DEMs: the Greek Cadastral DEM and the topographic maps of 1:5000. We applied in each DEM, for drainage basins oriented perpendicular to the fault, a series of geomorphic indices such as the drainage basin shape (Bs), the asymmetry factor (AF), the stream length-gradient index (SL), and the valley floor width to valley height ratio (Vf). These indices are used worldwide for fault activity classification. The indices calculated in the selected DEMs are compared with results from the Greek Cadastral DEM. Bs values range from 1.6 to 5.9 suggesting variably active basins, elongated according to Drainage Basin Form (RF) calculations. AF suggests systematic tilt down to the east or west. These three indices show high variability between different DEMs. Values of SL are relatively high close to the fault trace and range from 10 to 4500 and their visualization shows different narrow or inclusive patterns. Vf values range between 0.04 and 5.00 corresponding to an almost inactive fault when based on the SRTM 90 DEM to highly active using the Cadastral DEM. Our results suggest that the globally available ALOS products are quite accurate for the purposes of the tectonic geomorphology.

Tracking geomorphic recovery in process‐based river management

AbstractHuman disturbance induces significant geomorphic changes to river systems. In eastern Australia, land‐use practices such as clearance of forests and riparian vegetation, and removal of wood from channels in the 19th and 20th centuries induced widespread geomorphic impacts. However, since the 1970s, there has been a noticeable shift in the geomorphic condition of many rivers in eastern New South Wales (NSW). This transition to a recovery trajectory reflects a reduction in land‐use pressures and improved farming practices on the one hand and adoption of recovery enhancement approaches to river conservation and rehabilitation by management authorities on the other. Monitoring and tracking changes in condition by state government agencies involves identifying when geomorphic recovery is occurring so that decision‐support frameworks can determine whether river management is required, where, when, and how much to intervene to enhance river recovery and when to opt‐out of management because the system requires little (or no) intervention. Here, we document procedures that are used to manage process‐based, recovery enhancement in NSW. Following a brief review of river change in eastern NSW since European settlement, we outline an approach to identify and measure key geomorphic indicators of river recovery for different river types. We use case studies to demonstrate examples of geomorphic river recovery, prior to showing how state government agencies in NSW are monitoring trajectories and rates of recovery. Broader implications of this ‘good news story’ are discussed.

Quantitative analysis of relative tectonic activity in the Acıgöl fault, SW Turkey

This study was conducted in order to determine the relative tectonic activity of the Acigol Fault using geomorphic indices. The Acigol Fault is approximately 50 km long and was separated into four segments. For this purpose, the following geomorphic indices have been used: (1) mountain-front sinuosity (Smf), (2) valley floor width-to-valley height ratio (Vf), (3) basin asymmetry factor (AF), and (4) hypsometric curve and integral (Hi). When the results of Smf and Vf are evaluated, the uplift ratio was calculated as > 0.5 mm year−1 in the middle part of the fault, namely in the second and third segments, whereas this ratio is 0.5–0.05 mm year−1 along the NE nad SW margins of the fault. The Acigol Fault is normal fault based on both relative tectonic activity is moderate to high and downthrow is high in the middle part of the fault and low in the margins. In general, the Acigol Fault has relatively moderate to high tectonic activity and when the length of the fault is taken into consideration, generally speaking, the Acigol Fault has relatively moderate to high tectonic activity, and when the length of the fault is taken into consideration, it was concluded that the fault could produce a high-magnitude earthquake in the future.