Stream Length Gradient Research Articles

Exploring spatial variations in geomorphic features of a young intracontinental orogenic belt: A case study of the High Atlas range

Morphotectonic parameters are sensitive to crustal and/or mantle dynamics, especially in young convergent margins and contractional orogenic systems. In northwest Africa, the High Atlas orogen is a natural example where tectonics interact with mantle dynamics to shape the orogen's topography.The High Atlas Mountains are an intracontinental segment of the peri-Mediterranean belt in northwest Africa, formed during the Late Cretaceous-Cenozoic period as part of the Alpine orogeny. An important aspect in the evolutionary history of the High Atlas belt is the presence of uplifted asthenosphere beneath the range, overlaying the Late Cretaceous-Cenozoic crustal shortening. This study aims to investigate the geomorphic and topographic features that reflect the influence of tectonics and mantle dynamics in the High Atlas orogen. A morphotectonic approach is employed, utilizing analysis of geomorphic indices such as relief, slope, channel steepness index, and stream length gradient. Additionally, eleven 30 km wide and 150 to 230 km long swath profiles are constructed to illustrate the variations in topography and geomorphology along the range.The geomorphic indices display a similar pattern of evolution across the High Atlas, with higher values of these indices associated with the primary faults that control the structure of the range. By combining the geomorphic indices and swath profiles, it is evident that the eastern part of the orogen exhibits geomorphic asymmetry, with the northern border experiencing greater neotectonic activity and surface uplift. The central part of the range displays more geomorphic symmetry, while the western part is asymmetrical, characterized by higher elevations and elevated values of geomorphic indices along the southern border. This variation in geomorphology is attributed to the oblique intersection of the High Atlas orogen and a region of thinned lithosphere, which facilitated increased neotectonic activity and surface uplift in the northern part of the Eastern High Atlas and the southern part of the Western High Atlas. In the westernmost portion of the range, the role of structural inheritance is critical in the neotectonic activity. At a local scale, the role of lithology in the drainage reorganization is evident especially in basement exposures such as Mougueur inlier, Skoura inlier and Ouzellarh salient.This study underscores the robustness of tectonic geomorphology as a tool to understand the complex interplay between crustal processes and mantle dynamics, together with surface processes, in young orogenic belts like the High Atlas.

Assessment of active tectonics of the Tripura-Mizoram fold belt (Surma Basin), North East India

The Tripura-Mizoram fold belt is situated in the north-eastern part of India. Northeastern Himalaya including this region is tectonically very active, partly petroliferous, and has international attention from academicians and industry persons. This study aims at locating areas of recent tectonic vulnerability. Drainage networks are proxies of active faulting. Changes in geomorphic indices e.g., long profile analysis, basin-scale parameters, stream length gradient index and steepness index along the rivers in the eighteen watersheds extracted within the study area are evaluated. The Index of active tectonics (IAT) derived from the basin-scale parameters is classified into five classes: Class 1 (IAT =1.875–2.000), Class 2 (IAT = 2.001-2.375 ), Class 3 (IAT = 2.376-2.750), and Class 4 (IAT = 2.751-3.250) and Class 5 (IAT = 3.000‐3.320). Class 1 indicates the highest activity of tectonics. The tectonic sensitivity is also marked in micro-scale where rivers cross lineaments / faults. Elevations from source to mouth of individual consequent rivers of each watershed indicate the most vulnerable sections where the channels run along and across the faults or lineaments in watersheds 2, 14 and 15. The computed R2 values and the IAT identify watershed 2 and watershed 15 as the tectonically most active. Well-bore stability issue from the Petroleum mining lease (PML) blocks needs to be taken care from watershed 2, 3 and 15.

Excess topography and outburst flood: Geomorphic imprint of October 2023 extreme flood event in the Teesta catchment of Eastern Himalayas

The 2023 South-Lohnak Lake outburst flood event across the upstream Teesta catchment triggered short-lived, high-magnitude flooding and substantial socioeconomic disruption downstream. We performed landscape analysis across the Teesta catchment using topographic metrics to understand the geomorphic response to this extreme flood event. We estimated the various topographic metrics such as ksn anomaly (normalized channel steepness index) (∼500–2500 m0.9), SL-index (stream-length gradient index) (∼5000–7000 m), and KsnQ (channel steepness-weighted discharge) along the trunk channel draining through the South-Lohnak Lake, which shows high magnitude in flooded regions and numerous spikes in their longitudinal profiles across mass-wasting regions downstream. We used the KsnQ metric as an event characteristic to investigate the changes in the channel morphology due to high-magnitude flooding. There was a sudden increase in the magnitude of the KsnQ metric when the river traversed through the Chungthang dam over the high ranges of excess topography (∼0–1700 m). This shows that the downstream channel morphology changes rapidly during this flood event, and KsnQ is a significant indicator of geomorphic change. To understand the spatial relationship between the physical drivers that trigger this outburst flood, we quantified the causal relationship between glacial-hydrological drivers over the upstream Zemu-sub catchment. Our observations suggest that precipitation intensity and surface temperature had a significant direct causal influence on snowmelt and snow depth (in terms of water equivalent) over the event duration with a 5-day and 1-day lag composite. Through the inclusion of lagged composites and causal linkages, the drivers across the glaciated landscape serve as event anomalies, which trigger the glacier hillslope failure and subsequent high-magnitude outburst flooding. Therefore, we suggest that the interaction of topographic discontinuity with hydrological extremes and their causal interdependencies influences this outburst event in the upper reaches, followed by high-magnitude flooding in the downstream reaches of the Teesta River. However, the long-term geomorphic consequences of such events on the evolution of the regional landscape remain unclear.

Tectonic evolution of Bursa Yenişehir Basin, Turkey from the Neogene to the Quaternary using a morphotectonic approach

In this study, the morphotectonic features of the Yenişehir pull‐apart basin in Bursa in northwestern Turkey were analysed. The faults in the region are the most important structural elements that characterize the morphology of the Yenişehir pull‐apart basin. The aim of this study is to show the deformation effects of these active faults on the geomorphology with some basic morphometric indices. The morphotectonic features were evaluated using the hypsometric curve and hypsometric integral (Hi), drainage basin asymmetry (the asymmetry factor (AF) and the transverse topographic symmetry factor (T)), river length gradient index, mountain front sinuosity, and valley floor ratio. The morphometric indices that play an important role in the analysis of catchment areas are the Hi, AF, and T indices, which indicate tilting and erosion activities. According to the results of the hypsometric curve and hypsometric integral, the Yenişehir Basin is a young basin with a uniform topography as expected in an active pull‐apart basin formed by faulting in the Quaternary. The relative tectonic activity index (Iat) of the study area was calculated using the values of hypsometric integral, transverse topographic symmetry factor, asymmetry factor, mountain front sinuosity, valley floor ratio and stream length gradient index. The Iat values indicate the tectonic activity of the basin from Pliocene to Recent. Three different tectonic classes were identified in the study area. These are class 1 (high relative tectonic activity), class 2 (moderate relative tectonic activity), and class 3 (low relative tectonic activity). The Iat classification data show that the impact of tectonic activity on the geomorphology is lower in the Iat class 3 indices than in the others. The Iat data show high tectonic activity in the region where active faults of the North Anatolian Fault Zone southern branch are located.

Implications of active Gavilgarh/Salbardi fault on the evolution of the late Quaternary landscape in Central India

The morphometric indices (MI) have been calculated along the Gavilgarh/Salbardi Fault (G/SF) to investigate active deformation, tectonic uplift, and basin tilt to find out its impact on the late Quaternary landscape. To explore the tectonic intensity, we computed MI such as stream-length gradient index (SL), hypsometric integral (HI), transverse topographic symmetry factor (T), asymmetry factor (Af), basin elongation ratio (Re), mountain front sinuosity (Smf) and valley floor width to valley height ratio (Vf). The necessary field investigations were carried out on the evolution of the Quaternary landscape to ascertain the various morphometric indices. The evaluated values of SL, HI, Re, Smf, and Vf show the high uplift of the northern block exists as opposed to the southern block, and the tilt and asymmetric character of the basins are shown by T and Af values. The presence of sedimentary landscapes like Quaternary alluvium, triangular facets, natural levees, and boulder-pebbly beds, indicates that the area has recently experienced tectonic activity. The assessed values of MI with supporting field evidence proposed that the northern block is uplifted and the basins are tilted because of the effect of G/SF.

Quantitative assessment of relative tectonic activity in the eastern Bandung Basin, Indonesia

ABSTRACT The Eastern Bandung Basin is composed of predominantly Quaternary volcanic rocks and is influenced by tectonic activity. This research aims to determine and evaluate the morphotectonic characteristics and its implication to the potential geological disaster in the Eastern Bandung Basin. The morphotectonic indices used in this research consist of Stream Length Gradient Index (SL), Asymmetric Factor (Af), Hypsometric Integral (Hi), Ratio of the Valley Floor to the Height of the Valley (Vf), Basin Shape (Bs), and Sinousity of the Mountain Front (Smf). The research area consists of subwatersheds, namely Upper Citarik, Cijalupang, Ciwirama, Ciburial, Cikeruh, and Cimande. The research area is mostly located on hilly to mountainous area with flat to very steep slopes (0–56°). The research area is composed of Quaternary volcanic rocks in the north, east, and south as well as Quaternary alluvium in the central part of the research area. Based on the quantitative assessment, the research area has IRTA values of classes 3 and 4, indicating low to moderately active tectonics. It can be related to active faults and Quaternary volcanic rocks. Class 3 of IRTA corresponding to moderately active tectonics occurs mainly in the Upper Citarik and Cimande subwatershed. Class 4 of IRTA mainly takes place in the Cijalupang. Ciwirama, Ciburial, and Cikeruh subwatershed.

Morphotectonic Analysis in the Sombe Lewara Sub-Watershed in the Region of Palu City and Sigi Regency, Central Sulawesi Province

A study on the tectonic activity index (IAT) was conducted in the Sombe Lewara Sub-Watershed, encompassing the area of Palu City and Sigi Regency, Central Sulawesi Province. The objective of this research was to determine the level of tectonic activity in the Sombe Lewara Sub-Watershed. The analysis employed in this study was morphotectonic analysis, utilizing parameters such as Hypsometric Integral (HI), Basin Shape (BS), Asymmetry Factor (AF), Stream Length-gradient Index (SL), Area Factor (AF), and Valley floor width-to-height ratio (Vf ratio). The tectonic activity index (IAT) value in the Sombe Lewara Sub-Watershed was 1.6, which classifies it within the high tectonic activity category. This high level of tectonic activity in the research area influences the landscape conditions and the types of rocks present. The predominant rock types in the study area are sedimentary rocks such as conglomerate deposits, sandstone, siltstone, and claystone. These rocks form the character of an expansive alluvial fan landscape that nearly covers the entire plain. One of the primary factors contributing to liquefaction in the Balaroa Region is that the area is composed of sand sediment deposits and granite boulders that constitute the alluvial fan.

Geomorphic signatures of neotectonic activity along the Western Andean Front in the Chilean Andes (35°S to 37°S)

AbstractCharacterizing neotectonic activity along mountain fronts in active orogens is the key to better understanding trajectories of landscape evolution, climatic‐tectonic couplings and natural hazards. One such prominent mountain front is the Western Andean Front (WAF), which defines the boundary between two main physiographic units along the Chilean Andes (15°S to 39°S): the Central Depression and Principal Cordillera. This study analyses the geomorphic imprints of neotectonic fault activity in the WAF between 35°S and 37°S. We used several topographic metrics, including the mountain‐front sinuosity index (Smf), the valley floor width‐to‐height ratio (Vf) and the stream length‐gradient (SL) index to gain information about the regional distribution of deformation patterns and its relative tectonic activity for distinctive segments. In addition, a raster map combining rock strength (RS) and mean annual precipitation (MAP) allowed discriminating lithology‐climate vs. tectonics influence on SL anomalies from catchments spanning from the main deformation zone to the regional drainage divide. We use the local relief and swath profiles to quantify the incision and transient state of mountain fronts to evaluate the geomorphic response to tectonic and/or climatic input. Our analysis highlights significant variations from north to south, delineating two distinct segments with different topographic, geomorphic and geometric fault characteristics. These segments are indented at approximately 36°S. From north to south, there is a segment with an inactive thrust front with a primarily climate‐driven fluvial response over long timescales and a second segment with a transient state adjusting to relatively high uplift rates. Morphometric data analysis, DEM‐based morpho‐structural maps, geological maps and previous research support the interpretation of two sets of neotectonic faults: (1) NNE‐striking reverse faults with a dextral slip component and (2) NW‐striking sinistral slip faults, likely a response to deformation partitioning caused by oblique subduction on a continental margin.

Morphostructural influence and neotectonic activity in the geomorphological configuration of southeast Paraíba and northeast Pernambuco, Brazil

The current study provides critical insights into the field of geomorphology by examining the impact of lithological structures and tectonic activities on the geomorphological configuration of terrain and drainage networks in the southeast of Paraíba and northeast of Pernambuco, Brazil. This geographical region is characterized by phenomena of uplift and fluvial incision at various sites, yet remains inadequately explored with respect to its active deformation and the broader context of its recent geology. Therefore, the primary aim of this research is to elucidate the morphostructural and neotectonic influences on the geomorphological formations in these sectors of Brazil. The methodology encompasses morphostructural analysis, leveraging data derived from altimetry, slope, and geomorphology maps, categorized into taxonomic terrain units. Additionally, this research incorporates the use of morphometric indices, including the Stream Length-Gradient Index (SL), Valley Floor Width (VF), and Asymmetry Factor (AF) to quantify geomorphological anomalies. The analysis of the SL index indicates that a significant portion (87.5 %) of the drainage network exhibits anomalies. Furthermore, the VF index results reveal that 66 % of the profiles analyzed manifest anomalies of various magnitudes. Within the study region, the AF index elucidates the distribution of sub-basins into categories of low (0−30), medium (31−50), and high (>51) asymmetry, comprising 25 %, 31 %, and 44 % of the sub-basins, respectively. The sub-basins demonstrate channel disequilibrium, as evidenced by the SL index, attributed to numerous transient knickpoints along the drainage profiles. This observation is consistent with previous findings in the Koyna-Warna Shallow Seismic Region. The study's outcomes reveal both qualitatively and quantitatively anomalous patterns in the drainage network and terrain forms, which are likely indicative of recent tectonic events affecting the entire eastern edge of Northeast Brazil. Consequently, the findings highlight the significant role of post-Miocene tectonic events in shaping the relief of the study area.

Remote Sensing-based Morphometry on the Petroliferous Cambay Rift Basin (Gujarat, Western India)

Abstract The Cambay Rift Basin (CRB) is a product of rifting in western India that formed during India’s drift following the breakup of Gondwanaland during the Early Jurassic and Tertiary Periods. Being petroliferous, the basin has attained paramount attention. Seismicity in CRB proves its present-day tectonic sensitivity. Several NNW-SSE, NW-SE and NE-SW trending faults regulate the channel morphology within a portion of the basin. Drainage network systems are proxies of active faulting. Geomorphic indices e.g., long profile analysis, basin-scale parameters, stream length gradient index and sinuosity index along the main channels in the five watersheds have been evaluated in this work. The Index of Active Tectonics (IAT) is derived from the basin-scale parameters and is clubbed into three classes: class 1 (IAT = 1.4 - 1.9), class 2 (IAT = 1.91 - 2.4) and class 3 (IAT = 2.41 - 2.9). IAT Class 1 indicates a higher present-day tectonic activity than the other watersheds such as 1, 2 and 5. Watersheds in the northern and eastern Cambay region (watersheds 3 and 4, and portions of 1 and 5) exhibit higher tectonic activity. Slope breaks and low sinuosity index near the crossing-points in these northern and eastern portions indicate active / weak zones. Along these zones, channels incise vertically and more efficiently than laterally in watersheds 3 and 4. These weak zones may indicate older structures such as lineaments and faults. The Ahmedabad-Mehsana block in watershed 3 and partly in watershed 1 within the CRB with several oil fields are tectonically highly active. Therefore, well-bore stability studies need to be carried out in this block.

Neotectonic landforms of the Neoproterozoic basement of Southeastern Brazil: The case of the north border of the São Paulo Basin

Recent studies have demonstrated that the current tectonics activity plays an important role also in intraplate setting, such as in the Brazilian territory as a whole. The Continental Rift of Southeastern Brazil, which comprises the Neoproterozoic basement and some Paleogene basins (e.g. Taubaté, São Paulo, and Curitiba basins), is one of the most important features affected by Neotectonics, the tectonic regime acting since Neogene. However, information about the effects of the current tectonic regime on the rift surrounding areas is still missing. In this way, the objective of this research is to evaluate the possible effects of Neotectonics on the landform of the Neoproterozoic basement, close to the São Paulo sedimentary basin. In order to achieve this objective, general descriptive characteristics of the drainage system were analyzed, such as: network pattern, drainage and hydrographic densities, junction angles, trophy, and anomalies. These data were compared with the aeromagnetic data and the results of the Stream Length-Gradient (SL), Asymmetry Factor (AF), and Drainage Basin Shape (BS) indexes of the main rivers. In the field, 1330 measurements of tectonic features were surveyed in 122 outcrops. The paleostress orientations were calculated by means of fault and fracture inversions by Daisy3 software. In addition, Geologic-geomorphological Maps (1:25,000) of 3 key areas were prepared. The results suggest that tectonic structures have influenced the general arrangement of hills, ridges, and floodplains, as well as the general characteristics of the drainage system, responsible for the dissection of landforms. Recent deformations indicate Neotectonic activity causing tilting of blocks and channel migration, and formation of escarpments, triangular facets, abandoned meanders, fluvial terraces, knickpoints, and elbows. On the other hand, the field data suggest that the most of faults are related to the Pre Cenozoic tectonics. In this way, Neotectonics is not the principal structural element on the landform evolution of the study area, but it has an important role on the relief formation of some regions.

Geomorphic Imprints of Active Tectonics of the Bikaner-Nagaur Petroliferous Rift Basin and its Surroundings (Western Rajasthan, India)

Abstract Geology of sedimentary rift-basins require strong geomorphic input for a proper interpretation of active tectonics. Rift-related sedimentation took place in western Rajasthan of the Indian shield, which includes the Bikaner-Nagaur basin (BNB) and a few other adjacent basins. The sedimentation history of the BNB includes Proterozoic, Cambrian, Permo-Carboniferous and from Paleocene to the Recent. This study analyses river profiles with the best-fit curve (R2) model for the BNB and the surrounding regions. The research shows that the watershed 3 within the study area is most active tectonically, through which multiple faults and lineaments pass. Hypsometric Curves (HCs) of watersheds 1, 2 and 3 indicate that these watersheds are tectonically active. This inference is based on the concave profiles of HCs at the head, and convex profiles of HCs at the body and toe sections. Clustering of sixty segments (S) of the considered rivers based on linear-scale morphometric parameters, e.g., sinuosity index (SI), stream length gradient index (SL) and concavity (θ) enabled segment-wise comparison of river profiles with similar values. These segments were compared pair-wise, and Euclidean-based dissimilarity (dR) values were calculated between each such pair. The findings too imply that tectonic activeness exists in parts of watersheds 1, 2 and 3. The channel flow lines are controlled by faults/lineaments as per the micro-scale examination of the drainage network and faults/ lineaments analysis. Under structural control, nine major geomorphic units emerged with distinct erosional surfaces, denudational hillocks, dissected hills and inselbergs. Detailed geomorphic map with micro-scale studies revealed a slope retreat process that resulted in landforms viz., pediment, pediment slope and active flood plains.

Assessing Hydropower Potential in Nepal's Sunkoshi River Basin: An Integrated GIS and SWAT Hydrological Modeling Approach.

This study assessed the hydropower potential of a mountain watershed within the Sunkoshi River basin in Sindhupalchok, Nepal, utilizing geographic information systems (GIS) and the soil and water assessment tool (SWAT) hydrological model. Topographical, soil, land use, meteorological, and discharge data were employed to assess the study area for the appropriateness of hydropower generation. SWAT was utilized to delineate the Sunkoshi basin into 23 distinct subbasins and involved the creation of a detailed river network, incorporating various hydrological attributes including stream links, stream order, stream length, and slope gradient. After that, it was employed to simulate river discharges within these subbasins. The Sequential Uncertainty Fitting Version 2 (SUFI-2) algorithm, integrated within the SWAT Calibration and Uncertainty Program (SWAT-CUP), was employed to calibrate and validate the model. This step involved the adjustment of 25 selected parameters to enhance the model's accuracy and reliability in representing the hydrological processes of the Sunkoshi basin. Model performance was assessed utilizing three well-established efficiency criteria: coefficient of determination (R2 = 0.79), Nash-Sutcliffe efficiency (NSE = 0.73), and percent bias (PBIAS = 17.59). The study identified 36 sites across streams of order 3, 4, and 5 as having potential for hydropower generation. The hydropower potential at each identified site was evaluated using estimated stream flow and topographical head at various probability of exceedance (PoE) levels (40%, 45%, 50%, and 60%). The aggregate hydropower potential of the basin was quantified, yielding a potential of 371.30 MW at a 40% PoE. The findings suggest that an integrated approach combining SWAT-based hydrological modeling within a GIS can accurately assess a river basin's hydropower potential and provide insights into further evaluation of the comprehensive environmental assessment of the fragile Himalayan watersheds.

Assessment of On-going tectonic deformation in the Goriganga River Basin, Eastern Kumaon Himalaya Using Geospatial Technology

The Goriganga river basin lies in the Northeast Kumaon Himalaya and is found suitable for assessing active tectonics at different scales. In addition, this study focuses on the assessment of ongoing tectonic activity through morphotectonic measurement of the Goriganga river basin, which is an ideal location for such analysis and Goriganga river basin transects with three major domains of Himalaya’s lithotectonic structures viz., Tethys, Vaikrita, and Lesser Himalayan Domain. To realize this task, the ASTER Digital Elevation Model was used and found suitable to extract different morphotectonic indices such as Stream Length Gradient (SL), Hypsometric Integral (HI), Length of Overland Flow (Lg), Drainage Density (Dd) and Channel Sinuosity (Cs). Results of these important indices, including SL (18- 4737) HI (0.26- 0.57), and Lg (0.08- 0.19) depict greater variability in the tectonics activity while these values are correspondingly high in the close proximity of lithotectonic units, showing strong tectonic activity. In the extreme south, the Rauntis Gad basin strongly influences tectonism due to transecting syncline and anticline as well as unknown active faults.

Late Quaternary tectono‐geomorphological investigations of Zanskar Basin, NW Himalaya, India, using geospatial techniques

AbstractGeospatial techniques play a crucial role in geomorphic studies, particularly in the challenging terrains like mountainous regions, inaccessible areas and densely vegetated landscapes, where geomorphic features cannot be recorded easily. Tectono‐geomorphologic observations provide important clues regarding the landscape evolution, morpho‐dynamics and ongoing tectonism of the region. The present study has been carried out in the Zanskar Basin (ZB), located to the south of the Indus Tsangpo Suture Zone (ITSZ), in the hinterland of the NW Himalaya. This study has been carried out to assess and evaluate active tectonics by employing tectono‐geomorphic analysis, dynamics in drainage networks, geomorphological field observations and the Geographic Information System (GIS) environment. High‐resolution satellite images, topographic maps and the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) were used to generate primary data sets, which were corroborated with field investigations for valid inferences. The geometry of the ZB suggests that continuous tectonic activity exerts first‐order control on the overall shape, size and structure of the ZB. This first‐order response is clearly reflected in the landforms modified by tectonic processes, namely, linear mountain fronts, elongated shape and tilting of the basin, braided and meandering river courses and lower stream length gradient index values in hard rock terrain. The ZB exhibits several eye‐catching geomorphic features, such as well‐defined triangular facets with wide base lengths and wine‐glass valleys with small outlets along the footwall block of the Zanskar Shear Zone/South Tibetan Detachment System (ZSZ/STDS), as well as the presence of wind gaps, water gaps, bedrock incision, incised and entrenched valleys, narrow gorges and a high incision rate inferring active tectonics and recent uplift in the region. In addition, the existence of uplifted river terraces, as well as the stepped morphology of fans and strath terraces, suggests that the region is experiencing recent activity and ongoing tectonic uplift. These modified geomorphic characteristics suggest that the hinterland, which is part of the NW Himalaya, is tectonically quite active and has experienced a differential rate of tectonics during its evolution. The quantified geomorphic indices and their relations with the tectonics, climate and erosion activity infer that the basin geometry is mostly controlled by the ZSZ/STDS that dips 20°–70° NE, the south‐dipping Zanskar Counter Thrust (ZCT) and other local tectonic elements like the Choksti Thrust (CT), Stondgey Thrust, Zangla Thrust and tectonic structures. The synergised results of quantified geomorphic indices and tectono‐geomorphic evidence in the ZB strongly indicate that both the past and ongoing tectonism have significantly shaped and modified geomorphology of the ZB.

Tectono-geomorphic and active deformation studies in the Ujh basin of Northwestern Himalaya

This study focuses on the morphotectonic analysis of the Ujh River basin, examining various aspects related to geometrical changes in the drainage basin caused by tectonic and erosional processes. The topographic development of the Ujh River basin is a response to enhanced tectonic deformation caused by Main Central Thrust (MCT) and Main Boundary Thrust (MBT). We assume that the basin asymmetry, tilting, incision, and migration of the river basin are regulated by the compressive force generated between MBT and MCT. The results were characterized by a high Asymmetry Factor (Af) indicating greater asymmetry suggesting a rightward tilting with low Valley Floor to Valley Width (Vf) values which indicate differential uplift and incision owing to ongoing tectonic processes. The high Stream Length Gradient (SL) Index values in the MCT zone, indicate sudden topographic breaks caused by the vertical tectonic uplift with active erosion processes. The Ujh River basin is in a disequilibrium state, with convex portions indicating uplift and concave portions indicating subsidence on the slope-area plot. The χ analysis, plotting χ values against elevation, highlights upliftment and erosion zones along the trunk stream, with major slope breaks and high χ values observed in the upstream region, particularly along the MCT. Overall, the Ujh River basin exhibits morphotectonic characteristics indicating ongoing tectonic activity and a state of disequilibrium.

Geomorphic signatures and active tectonics in western Saurashtra, Gujarat, India

Active tectonics in an area includes ongoing or recent geologic events. This paper investigates the tectonic influence on the subsidence, uplift and tilt of western Saurashtra through morphotectonic analysis of ten watersheds along with characteristics of relief and drainage orientation. Watersheds 7–9 to the north (N) are tectonically active, which can be linked with the North Kathiawar Fault System (NKFS) and followed by watersheds 6, 10, 1, 4 and 5. Stream-length gradient index and sinuosity index indicate the effect of tectonic events along the master streams in watersheds 6–9. Higher R2 values of the linear curve fit for watershed 7 indicate its master stream is much more tectonically active than the others. The R2 curve fitting model and earthquake magnitude/depth analysis confirm the region to be active. The reactivation of the NKFS most likely led to the vertical movement of western Saurashtra.

Investigating the Tectonic and Structural Controls on the Geomorphic Evolution of Shiriya River Basin, Southern India

Abstract Morphotectonic analysis of a river basin using geomorphic indices helps to identify tectonic deformation. The aim of the present work is to determine geomorphic indices from the digital elevation model and to examine the extent to which structural characteristics of the Shiriya River Basin (SRB) have influenced its drainage morphology. GIS techniques are used to calculate geomorphic indices of the SRB. Morphotectonic and geomorphic analyses were carried out, which included evaluating various geomorphic indices. Hypsometric curve and hypsometric integral (0.46) indicate youth stage of the basin, asymmetry factor (43.23) and transverse topographic symmetry factor (0.37) indicate asymmetry of the basin, basin shape index (2.05) depicts the basin as elongated, sinuosity index (1.47) indicate the sinuous nature of the basin, valley floor width to height ratio is 10.21 and stream length gradient index is 113.75. The entire basin is divided into 18 fourth-order sub-basins for detailed analysis of morphotectonics. Relative active tectonic indices are calculated to identify the subbasin that had undergone pronounced structural disturbance. Out of 18 subbasins 13 subbasin belongs to moderate tectonic active category (class-2) and 5 subbasin belongs to active category (class 2). From the morpho structural analysis following results were arrived, all of which point towards significant structural control: Lower-order streams have an orientation in accordance with significant structural elements of the basin, such as foliations and lineations (E-W). Similarly, the alignment of higher-order streams follows the direction of the major lineaments of the basin (NW-SE). Eight waterfalls/cascades are positioned within the basin, all directed in accordance with the lineament (NW-SE), earthquake recorded near the basin, asymmetry of the basin, acute bending of streams, entrenched meanders, changes in the sinuous river path in several locations where lineament intersect the stream and shrinkage of estuary area indicate neotectonics and structural control over the development of drainage system in the SRB. These findings are essential for understanding the development of river drainage and landform evolution.

Morphometric Analysis of Tectonically Active Bhimtal-Naukuchiatal Lake Basin, Kumaun Himalaya

Bhimtal-Naukuchiatal region, which is an integral part of the Kumaun Lesser Himalaya, is sensitive to natural disasters and has a fragile environment as a result of neotectonic activity along the thrust and secondary thrust/faults. With regard to neotectonic activity, this study aims to comprehend the tectonic instability of the basin. Morphometric analysis is a computable research of landforms that is crucial to understanding how the landscape has evolved in response to nearby tectonic activity. In present exercise we have calculated ten morphometric indices, viz., Valley floor width-height ratio (Vf), Hypsometric Integral (HI), Stream-Length gradient Index (SL), Bifurcation ratio (Rb), Drainage density (Dd), Stream Order (Sµ) and average Sinuosity (S), Relief (H), steepness (Ksn), Chi integral (?) and Asymmetric Factor (AF). The result shows low values of Vf indicate high upliftment rate, more incision and less channel down cutting. Most morphometric results suggest tilted basin, resulting in V-shaped valleys and a distorted and unstable longitudinal profile, which indicate the area is governed by both tectonics and lithology. The field geomorphic features along with the software based calculations suggest that the Bhowali-Bhimtal-Naukuchiatal is tectonically active zone.

Geospatial Analysis for Relative Seismic Activity Assessment: A Case Study of Fatima Suture Zone in Western Saudi Arabia

In this paper, we state the usefulness of geomorphic analysis, typically applied to highly deformed landforms, to investigate the tectonic geomorphology of an intercontinental structure: the Fatima suture zone. The Fatima suture zone (FSZ) landscape is a tectonically distinct deformation zone along the eastern coast of the Red Sea in western Saudi Arabia providing a complex zone in terms of geology, tectonics, and geomorphology. This zone presents many deformations and fault reactivations that were produced from the effect of horizontal, vertical, and thrust motions as well as deposition and erosion processes. Through several morphometric analyses, remotely sensed data, and geospatial techniques, we recognized the detailed geomorphic surface features of the Fatima suture zone region. Morphometric indices applied in this paper include the stream length gradient index (SL), basin asymmetry factor index (Af), hypsometric integral index (Hi), valley floor width to valley floor height ratio index (Vf), basin shape index (Bs), and mountain front sinuosity index (Smf). Every single morphometric index provides three different relative tectonic classes based on the assigned value ranges. The overall results obtained from the analysis were averaged and presented as an indicator index namely the relative seismic activity (RSA) index, which was classified into four distinct classes from relatively very high to low seismic activity: class 1 is very high seismic activity (CA ≤ 1.5); class 2 is high seismic activity (1.5 < CA ≤ 2); class 3 is moderate seismic activity (2 < CA ≤ 2.5); and class 4 is low seismic activity (CA > 2.5). Additionally, a combination of the two indices (Smf and Vf) was presented as a quantitative model of the relative seismic activity of the examined mountain fronts. The results of the RSA index provided signatures of all four classes of the study region. Two-thirds of the total area of the study region were recorded as high to very high classes in terms of seismic activity. The paper finally concludes that this integration method allows assessment and evaluation of the highly deformed landscapes related to active tectonism. Despite the impact of the Fatima suture zone providing low to medium activities in some parts, it has a signature control on the recent landscape evolution.