Stream Courses Research Articles

Tectonic geomorphology and structural architecture of eastern Sulaiman Fold Thrust Belt (SFTB) and adjacent Sulaiman Foredeep (SF), northwest Pakistan

This investigation combines a number of datasets to provide an enhanced and improved tectono-geomorphological framework with which to identify new possible structural lineaments in northwest Pakistan. The dataset includes satellite images and geographic information system (GIS) methods. The present study was carried out using the USGS ASTER DEM (30 m), Landsat 8 (OLI/TIRS) and surface field geology of the study area. Different band combinations, directional filters and principle component analysis (PCA) methods were used to identify the major structural styles and tectonic geomorphological pattern. The panchromatic band (Band-8) was applied to the Landsat 8 satellite images in order to increase the spatial resolution from 30 m to 15 m which aided in the investigation and comparative analysis of tectonic geomorphology and structural styles. Drainage patterns of Zindapir Anticline (ZA), Sakhi Sarwar (SS), Sulaiman Foredeep (SF) and Kingri Fault (KF) areas were generated using Strahler order of streams. The results suggested a combination of the dendritic network with a minor component of trellis pattern for ZP and SF areas, hence proposing a combined structural and stratigraphic/lithological control, whereas the KF area indicated an element of a rectangular pattern suggesting a more structural influence in the western part in comparison to the eastern region. The presence of water gaps (WaGs) and active drainage network indicate lateral growth and propagation directions of the ZP and SS frontal anticlines following the Paleocene Epoch. The geomorphic evidence coupled with satellite data show that the SFTB is tectonically active along with the adjacent SF. The stream courses are deflected or guided due to active folds and tectonics in the area characterized by the distinct fluvial erosional pattern on the flanks/limbs of ZA. Evidence from the study suggests that compressional deformation, uplift and erosion played a significant role in the shaping of the structural and depositional architecture of the basin. It is proposed that the deformation in the SFTB during the late Paleogene is related to the Indian-Eurasian oblique collision, while the subsequent late Tertiary collision of Indian Plate with the Afghan Block (an accreted part of southern Eurasia) further ensued compressive deformation. The results from this study elucidate the possible models proposed for this compressional regime with prevailing wrenching by presenting new data. The findings from this research reveal new tectono-geomorphological features and lineaments in the area that were not documented previously.

Paleotopography and anthropogenic deposition thickness of the city of Aachen, Germany

ABSTRACT The main objective of this study is to reconstruct the pre-Roman topography under the city of Aachen, Germany. Aachen has a 2000-year settlement history, and enormous amounts of anthropogenic deposits have accumulated during this time; these deposits are thus also visualized. The key data used are archeological excavation records and geological drilling documents that contain elevation and spatial data, and the Kriging algorithm was used to interpolate these data to produce two high-resolution raster datasets showing both the paleotopography and thickness of anthropogenic deposits. The paleo-DEM was then employed to reconstruct the course of former streams running through the study area. This research provides new insights into the topographic preconditions encountered by the first Roman settlers. As the accumulation of anthropogenic deposits in distinct areas of the city is linked to specific historical periods, the results also reveal the developmental stages of the ancient city.

How the body shape changes by the habitat hydrological factors in freshwater benthic fishes; case study on the genera Cobitis (Cobitidae) and Ponticola (Gobiidae)

Benthic fish groups with low mobility are often restricted to a narrow range of a stream course, and their morphological characters tend to be affected substantially by the environmental conditions in their habitat. Due to morphological affectability of fishes by many factors in lotic ecosystems, a landmark-based hypothesis was used to investigate the effects of habitat hydrological conditions on morphological characteristics in freshwater benthic fishes; a case study on the genera Ponticola and Cobitis . A total of 216 gobies and 128 spined loaches specimens were caught from six rivers with different hydrological conditions, along the southern Caspian Sea basin. In discriminant function analysis (DFA), the overall assignment of gobies and loaches into their original groups were 95.7% and 80.5%, respectively. Discriminant analysis for pairwise groups shows a longer snout, shallow body/head, and elongated body for populations living in the large slope channel with faster water velocity versus relatively short snout and deep body/head for those living in small slope channel with slower water velocity. The results confirm the possibility of changes in the morphological characters of the benthic gobies and loaches, which should be considered in taxonomical and biological studies.

Dynamics of the temperature regime of the North Atlantic coastal zone as an indicator of changes in the system of thermohaline circulation

The purpose of the article is to analyze dynamics of the temperature regime of the surface layer of the atmosphere in the coastal zone of the North Atlantic as an indicator of changes in the thermohaline circulation system. In carrying out the research, comparative-geographical and historical statistical methods of the analysis of meteorological series were used. For research, 20 control points of the eastern part of the United States and Western Europe, which are located along the flow course of the Gulf Stream, are selected. In the selected points, by means of the linear trend method, the regularities of the dynamics of the mean annual, average maximum and average minimum temperatures of the atmospheric surface layer for the period from 1973 to 2013 have been established. The results of the study showed that, contrary to the hypothesis of fall in temperature in Europe, an increase in average annual and average maximum temperatures is observed in all control points of the region - the range means the linear trend is from 0.9 to 4.4 o F and from 0.3 to 3.8 o F respectively. In most US control points, the average annual temperature rises from 0.1 to 3 o F and the average maximum temperature rises from 0.2 to 2.1 oF. For four points of the United States the decrease in the values of the linear trend of average annual temperatures is from -0.4 to -1.2 o F; for three points - a decrease in average maximum temperatures is from -1.3 to -1.9 o F. At 9 control points in the USA and 8 control points in Europe, the average values of the minimum temperatures in the research period increased - in the USA, from 0.1 to 3.1 o F; in Europe from 0.3 to 4.6 o F. The opposite dynamics in the regions is observed for the values of the temperature amplitude. In most control points in Europe, the difference between the average maximum and the average minimum annual temperatures ranged from 0.4 to 6.6 o F; in most US destinations, on the contrary, a decrease in the amplitude value from -1.6 to -3 oF is observed. The analysis of the temperature dynamics of the surface layer of the atmosphere indicates the prevailing warming processes in the coastalzone of the North Atlantic, more intense for control points in Western Europe. The obtained data give grounds for refuting hypotheses of the presence of critical deviations in the thermohaline circulation system of the Atlantic Ocean, which could lead to a cooling in the Northern Hemisphere. The change in the amplitude values is a manifestation of increasing instability of the climate, which is likely to remain in the future with a general increase in the mean annual temperature in the region.

Significance of the connection between bedrock, alluvium and streams: A spatial and temporal hydrogeological and hydrogeochemical assessment from Queensland, Australia

Catchment-scale hydrological and hydrogeological investigations commonly conclude by finding that particular stream reaches are either gaining or losing; they also often assume that the influence of bedrock aquifers on catchment water balances and water quality is insignificant. However, in many cases, such broad findings are likely to oversimplify the spatial and temporal complexity of the connections between the different hydrological system components, particularly in regions dominated by cycles of droughts and flooding. From a modelling perspective, such oversimplifications can have serious implications on the process of identifying the magnitude and direction of the exchange fluxes between the surface and groundwater systems.In this study, we use 3D geological modelling and historic water chemistry and hydraulic records to identify the origins of groundwater at different locations in the alluvium and along the course of streams in the Lockyer Valley (Queensland, Australia), a catchment impacted by a severe drought (‘Millennium Drought’) from 1998 to 2009, followed by extensive flooding in 2011. We also demonstrate how discharge from the sub-alluvial regional-scale volcanic and sedimentary bedrock influences the water balance and water quality of the alluvium and streams. The investigation of aquifer geometry via development of a three-dimensional geological model combined with an assessment of hydraulic data provided important insights on groundwater flow paths and helped to identify areas where bedrock aquifers interact with shallow alluvial aquifers and streams. Multivariate statistical techniques were then applied as an additional line of evidence to groundwater and surface water hydrochemical data from large historical datasets. This confirmed that most sub-catchments within the Lockyer Valley have distinct water chemistry patterns, which result from mixing of different water sources, including discharge from the sub-alluvial bedrock. Importantly, in addition to the observed spatial variability, time-series hydrochemical groundwater and surface water data further demonstrated that the hydraulic connection between alluvial aquifers, streams and sub-alluvial bedrock aquifers is temporally dynamic with very significant changes occurring at the transition from normal to drought conditions and following flooding, affecting both catchment water quality and water balances.

Geomorphic characteristics of landscape development and formation of lakes in the zone of Munsiari Thrust, Garhwal Himalaya, Uttarakhand, India

The present investigation is focused on imprint of tectonic perturbation along a major tributary, known as the Lastar Gad (Gad = River), in southeast catchment of the Mandakini river in Garhwal Himalaya. Based on morphotectonic studies across the watershed, we recognized evidences of neotectonics along the Jutogh/Munsiari Thrust (MT/MCT-II). Various geomorphic features, e.g., ponding of streams and formation of lakes, fluvio-lacustrine deposits, waterfalls, stabilized and active landslide fans, dissected hills, paired and unpaired terraces, fault scarps and offsetting of drainage pattern etc., point to the active tectonics. The field investigations are supported by computation of morphometric indices, such as, low values of Valley Floor Width to Valley Height (Vf), Asymmetry Factor (Af), elongated and tilted river basin with narrow valley floor as well as higher Bifurcation Ratio (Rb) and sinuosity parameters, immature topography and landscape, elongation and tilting of drainage basin and accelerated erosion-all show that the basin is structurally controlled. The uplift along the valley is further manifested by two significant indexes, e.g., Stream Length (SL) and Steepness Index (Ks). Also, the mud deposits, lacustrine flats and swampy and soggy land within the valley suggest the existence of an ancient lake basin, named as Gethina palaeolake, downstream of present day Badanital lake. The 14C AMS radiocarbon chronology of the Badanital lake core as well as Gethina-Jagtoli palaeolake profiles indicate the formation of these lakes around 5–6 ka BP due to tectonic upheaval along the MT. We assume that a huge landslide activity blocked the course of a small stream (Badani Gad), forming an ancient lake at Gethina locality, followed by deposition of a landslide fan on which was created the Badanital. Subsequently, the palaeolake basin was filled with sediments due to accelerated erosion from almost vertical hills in the catchment. Owing to this, the Gethina (ancient) lake was disappeared and the modern Badanital lake shrank to its present state.

Flood risk modelling of the Slatvinec stream in Kružlov village, Slovakia

This paper presents the methodology and results of water flow modelling focusing on the open channel of the Slatvinec stream running through the north-east Slovakian village of Kružlov. The underlying study involved: i) developing a flood model using Hydrologic Engineering Center's River Analysis System (HEC-RAS); ii) identifying areas of flood risk in the village using Geographic Information System (ArcGIS); iii) evaluating flood damage using Cost Analysis (CA). The model created in HEC-RAS software using the data collected enabled the water level in the stream profiles, flow rate and velocity, and finally the potential extent of flooding to be determined. The benefit of this research lies in the exact identification of the flood-risk areas along the course of the Slatvinec stream through the village of Kružlov, using a flood model of the area created on a Geographic Information System platform. Cost analysis is useful for evaluating flood damage to property, and the results of this hydrodynamic modelling may contribute to scientific research and to the practical application of flood mitigation and protection measures in other areas.

Phylogeography and population genomics of a lotic water beetle across a complex tropical landscape.

The habitat template concept applied to a freshwater system indicates that lotic species, or those which occupy permanent habitats along stream courses, are less dispersive than lentic species, or those that occur in more ephemeral aquatic habitats. Thus, populations of lotic species will be more structured than those of lentic species. Stream courses include both flowing water and small, stagnant microhabitats that can provide refuge when streams are low. Many species occur in these microhabitats but remain poorly studied. Here, we present population genetic data for one such species, the tropical diving beetle Exocelina manokwariensis (Dytiscidae), sampled from six localities along a ~300km transect across the Birds Head Peninsula of New Guinea. Molecular data from both mitochondrial (CO1 sequences) and nuclear (ddRAD loci) regions document fine-scale population structure across populations that are ~45km apart. Our results are concordant with previous phylogenetic and macroecological studies that applied the habitat template concept to aquatic systems. This study also illustrates that these diverse but mostly overlooked microhabitats are promising study systems in freshwater ecology and evolutionary biology. With the advent of next-generation sequencing, fine-scale population genomic studies are feasible for small nonmodel organisms to help illuminate the effect of habitat stability on species' natural history, population structure and geographic distribution.

Geospatial Modeling of River Systems

Within the context of fluvial systems, geospatial modeling of river networks consists of describing certain patterns in the geographical or geomorphological “fabric” along the course of rivers or streams and correlating these patterns to physical, ecological, biological and chemical processes in the river/stream system’s aquatic environment. Patterns may consist of different sets of similar sequences of geomorphological characteristics, sediment substrate type or flow velocity fields. These patterns will influence processes by defining, for example, behaviors in river ice formation or breakup (physical), fish habitat types (ecological) and transformations in water-quality constituents (biological and chemical). In this special issue of Geospatial Modeling of River Systems, we invited papers to present models and data that correlate geographic/geomorphic features of a river or stream system with physical/ecological/biological/chemical processes in the lotic aquatic environment.

Concentrations of Polybrominated Diphenyl Ethers (PBDEs) in Water from Asunle Stream, Ile-Ife, Nigeria.

This study assessed the concentrations of polybrominated diphenylethers (PBDEs) in stream water obtained from Asunle stream, an adjoining stream of the Obafemi Awolowo University dumpsite. Water samples were collected for a period of eight months from six different locations comprising of a spot upstream in an uphill area relative to the refuse dumpsite and five others downstream along the stream course. The sampled waters were extracted with dicholoromethane using liquid-liquid extraction method and cleanup was carried out with silica gel. The final extracts after concentration were analyzed using GC-MS/MS. The recovery experiments were adequate (105%–110%). The mean levels of Ʃ6PBDEs compounds analyzed ranged from 0.03 to 0.45 ng/mL. Seasonal variability of PBDEs indicated that higher levels were found during the wet season. The levels of PBDEs recorded in this work were relatively lower compared to the values reported in the literature from other developed nations.

Sedimentary environment and geomorphic development of the uppermost Siwalik molasse in Kumaun Himalayan Foreland Basin, North India

An area of about 250 sq. km. around Ramnagar and Garjiya within the Siwalik molasse in the Kumaun foothills was mapped for geomorphic evolution and sedimentation pattern. The area, bounded by Himalayan Frontal Thrust (HFT) in the south and Main Boundary Thrust (MBT) in the north, consists of the sediments of uppermost part of the Pinjor and overlying Boulder Conglomerate Formations. Sedimentologically, three facies associations (FAA–FAC) were recognized with their order of superposition as FAA → FAB, FAA → FAC, FAB → FAC and FAC → FAB with variability in depositional setting. Lithofacies FAA–FAC were seemingly deposited in sand‐dominated fluvial channel belt, gravelly braided channel belt and cut‐off channel settings, respectively. The sediment dispersal in the basin was influenced by active basinal tectonics that caused frequent avulsions during the Bounder Bed times. The compositions of the clasts of these lithofacies reveal a shift in the primary provenance from pre‐Tertiary Himalayan hinterlands during the emplacement of FAA (of the Pinjor Formation) to evolving frontal Siwalik highlands during the emplacement of FAB and FAC (of the Bouldder Conglomerate Formation). This temporal shift in the provenance indicates exhumation of the older Siwalik sequences during the later phases of Himalayan orogeny. A number of subordinate faults, oblique to above mentioned intracrustal boundary thrusts and formed after the sedimentation was seized, were likely responsible for displacement between the sediments of different associations. The neotectonic rejuvenation is also reflected by the upliftment of two sister basins in opposite direction, rapid uplift in V‐shaped valleys, fault escarpments, three levels of terrace development and displacement of rock types along the subordinate faults as well as deflection and entrenchment in the course of lower order streams. Copyright © 2017 John Wiley & Sons, Ltd.

Chapter 13 Jadeitite and other high-pressure metamorphic rocks from the Jade Mines Belt, Tawmaw area, Kachin State, northern Myanmar

The world's largest jade deposit, containing the highest-quality jade, is exposed in the Pharkant-Tawmaw (also spelled Hparkant or Hpakan and Tawhmaw) Jade Mines Belt, northern Myanmar. This belt is located between latitudes 25° and 26° N and longitudes 96° 12′ and 96° 25′ E in the Myitkyina district (Fig. 13.1). The belt extends in a north–south direction, covering an area of c. 1200 km2 (Chhibber 1934 b ). Major jade production sites are located in the Pharkant, Lonkin, Tawmaw, Haungpa and Hwekha areas. In these areas the rock type jadeitite, containing more than 90 vol% of the mineral jadeite, is associated with serpentinites, albitites, low- to medium-grade metamorphic rocks, chlorite schists, garnet–mica schists, graphite schists, glaucophane schists and amphibolites. Fig. 13.1. Geological map of the Jade Mines Belt (JMB) showing the localities mentioned in the text and the location of the samples described. Compiled by Thet Tin Nyunt, modified from Chhibber (1934 a ), Bender (1983), Than Tun (1997) and Thet Tin Nyunt (2009). The Jade Mines area of northern Myanmar is a highly dissected upland, higher in the north than in the south, with ranges of hills forming the Chindwin–Irrawaddy watershed. The main jade area around Tawmaw is situated on a plateau 840 m above sea level. Mountain ranges in the western part of the area rise to 600 m and are covered by dense vegetation. The eastern margin is bounded by the Uru River. The Tawmaw area is characterized by very high rainfall and, due to the tropical climate, the rocks are highly weathered and covered by a reddish-brown soil of thickness a few metres to tens of metres. Fresh samples of jadeite can be collected only from mine sites or from stream courses. In the Tawmaw area jadeitite is quarried from both primary deposits and as …

EFFECT OF RIVER SUPPLY ON THE DISTRIBUTIONOF MACROELEMENTS IN THE SEDIMENTS OF A RETENTION RESERVOIR - A CASE STUDY OF LOJE RESERVOIR

The aim of the studies was to evaluate the influence of the 30-year operation of a small retention reservoir fed with water from a forest-agricultural catchment area on the contents of selected mineral elements substances in bottom deposits. The studies were carried out in the Loje dam reservoir (N 53o7 28 , E 20o48 20 ), supplied by the regulated Loj wka stream. Deposit samples were collected in four transects perpendicular to the reservoir axis in the center of riverine and lacustrine zones and two transects in the transitional zone. In the sediment samples, the following parameters were determined: dry matter content, pH (in H2O) and the concentrations of organic matter, organic carbon, total nitrogen, total phosphorus, potassium, calcium, sodium, magnesium, iron, sulfur, chlorides, copper, manganese and zinc. Changes in the reservoir were evaluated with the use of geochemical indicators (C:N, Fe:Ca, Fe:Mn, Cu:Zn, Ca:Mg). The results showed the highest content of organic matter and its components (Ntot., Ptot., Ca, Na and Mg) in deposits sampled along the course of the main water stream flowing through the reservoir. In deposits sampled from the reservoir's riverine and transitional zones, the predominant macroelement was Ca, and in samples from the lacustrine zone Fe. On average, the content of the analyzed macroelements in deposits sampled from various zones created the following descending order: Ca > S > Ntot. > Fe > Mg > K > Ptot. > Na. Our results indicate that the accumulated deposits had been formed in shallow waters and that organic matter originated mainly from macrophytes and higher plants rich in cellulose.

Evaluation of Hydrogeomorphological Landforms and Lineaments using Remote Sensing and GIS Techniques in Ramannapet Mandal, Musi River basin, Nalgonda District, Telangana

The IRS -P6 LISS-IV satellite data is used to demarcate Hydrogeomorphology land forms and lineaments on 1;10000 scale to evaluate groundwater potential of the study area. The Ramannapet Mandal area of Musi river basin is occupied mostly by hard rock they are granites and gneisses of Archaean age with intrusive bodies of dolerites, and of the portion of the study area is covered mainly by both wet and dry cultivation. The major geomorphic unit identified in the area are, Denudational hills, Residual hills, Inselbergs, Dykes, Pediment inselberg complex, Pediment, Pediplain and valleys. Most part of the study area is occupied by Pediplain with various thickness and the groundwater potential is directly related to thickness of Pediplain. The object of the study is Remote Sensing imagery with its synoptic coverage acts as a tool for finding suitable solution when combined with conventional data. Hydro-geomorphic maps were prepared by integrating the Lithology, landforms, and structural fabric and hydrology layers and drainage layers using Remote Sensing and GIS techniques, the scale range of 1: 10,000. The lineament density map was generated in GIS software using Kriging method (Sabins, F. F., (1997). Outcomes of the study Based on visual interpretation and field investigations the different types of hydro geomorphic units observed in the study area. The recent alluvium deposits are present along the stream courses. Field observations shows that groundwater occurs under unconfined conditions with water table shallow to deep depth. from the lineament density and lineament intersection maps prepared to understand the impact on groundwater percolation. Finally, Hydrogeomorphology and lineament maps area overlaid following the weighted index overlay method, which delineate groundwater potential zones. an integrated Remote sensing and GIS based approach has been used for demarcating groundwater potential zones in the study area. The study area Ramannapet Mandal is in northern part of the district of Nalgonda, Telangana State, India. The study area people occupation is agricultural, and poultry, 80 percent of the people depending only agricultural activity

Erratum to: Mapping sediment thickness of Islamabad city using empirical relationships: Implications for seismic hazard assessment

Soft sediments make an important component of the subsurface lithology, especially in areas underlain by river/stream basins. Occupying a position directly above the bedrock up to the land surface, these soft sediments can range in thickness from few centimeters to hundreds of meters. They carry a special nuisance in seismic hazards, as they serve as a source of seismic amplification that may enhance the seismic shaking of many folds. Determination of the thickness of the soft sediments is therefore crucial in seismic hazard analysis. A number of studies in recent years have demonstrated that frequency and amplitude spectrum obtained from the noise measurements during the recording of natural seismicity can be used to obtain thickness of soft sediments covering the bedrock. Nakamura (1989) presented a technique to determine such spectrum using ratio of horizontal to vertical components of the Rayleigh waves. The present study is based on an extensive set of microtremor measurements carried out in the Islamabad city, Pakistan. Fundamental frequencies were obtained from weak motion sensors and Tromino Engy Plus instruments to show that the correlation is clearly valid for a wide range of sediment thickness. A simple formula was derived for the investigated area to determine directly the thickness of sediments from the main peaks in the H/V spectrum for seismometer and Tromino data separately. A comparison is made between sediment thicknesses derived from empirical relations developed in this study with those given in literature to demonstrate a positive correlation. The correlation of instrumental resonant frequencies with calculated resonant frequencies (theoretical) suggests that the relation derived from the noise measurements mostly depends on the velocity depth function of the shear wave. The fundamental frequency of the main peak of spectral ratio of H/V using the both instruments correlates well with the thickness of sediments at the site obtained from the borehole data. It is found out that there is a wide variation in soft-sediment thickness in the Islamabad area, but as a general rule, soft sediments are thicker adjacent to stream courses compared to the areas intervening the streams. The distribution of sediments in the studied area is illustrated by means of cross sections constructed from results of the microtremor analyses and available borehole data, which provides a visual distribution of the soft sediments underlying the Islamabad city.

Mapping sediment thickness of Islamabad city using empirical relationships: Implications for seismic hazard assessment

Soft sediments make an important component of the subsurface lithology, especially in areas underlain by river/stream basins. Occupying a position directly above the bedrock up to the land surface, these soft sediments can range in thickness from few centimeters to hundreds of meters. They carry a special nuisance in seismic hazards, as they serve as a source of seismic amplification that may enhance the seismic shaking of many folds. Determination of the thickness of the soft sediments is therefore crucial in seismic hazard analysis. A number of studies in recent years have demonstrated that frequency and amplitude spectrum obtained from the noise measurements during the recording of natural seismicity can be used to obtain thickness of soft sediments covering the bedrock. Nakamura (1989) presented a technique to determine such spectrum using ratio of horizontal to vertical components of the Rayleigh waves. The present study is based on an extensive set of microtremor measurements carried out in the Islamabad city, Pakistan. Fundamental frequencies were obtained from weak motion sensors and Tromino Engy Plus instruments to show that the correlation is clearly valid for a wide range of sediment thickness. A simple formula was derived for the investigated area to determine directly the thickness of sediments from the main peaks in the H/V spectrum for seismometer and Tromino data separately. A comparison is made between sediment thicknesses derived from empirical relations developed in this study with those given in literature to demonstrate a positive correlation. The correlation of instrumental resonant frequencies with calculated resonant frequencies (theoretical) suggests that the relation derived from the noise measurements mostly depends on the velocity depth function of the shear wave. The fundamental frequency of the main peak of spectral ratio of H/V using the both instruments correlates well with the thickness of sediments at the site obtained from the borehole data. It is found out that there is a wide variation in soft-sediment thickness in the Islamabad area, but as a general rule, soft sediments are thicker adjacent to stream courses compared to the areas intervening the streams. The distribution of sediments in the studied area is illustrated by means of cross sections constructed from results of the microtremor analyses and available borehole data, which provides a visual distribution of the soft sediments underlying the Islamabad city.

Active Crustal Faults in the Forearc Region, Guerrero Sector of the Mexican Subduction Zone

This work explores the characteristics and the seismogenic potential of crustal faults on the overriding plate in an area of high seismic hazard associated with the occurrence of subduction earthquakes and shallow earthquakes of the overriding plate. We present the results of geomorphic, structural, and fault kinematic analyses conducted on the convergent margin between the Cocos plate and the forearc region of the overriding North American plate, within the Guerrero sector of the Mexican subduction zone. We aim to determine the active tectonic processes in the forearc region of the subduction zone, using the river network pattern, topography, and structural data. We suggest that in the studied forearc region, both strike-slip and normal crustal faults sub-parallel to the subduction zone show evidence of activity. The left-lateral offsets of the main stream courses of the largest river basins, GPS measurements, and obliquity of plate convergence along the Cocos subduction zone in the Guerrero sector suggest the activity of sub-latitudinal left-lateral strike-slip faults. Notably, the regional left-lateral strike-slip fault that offsets the Papagayo River near the town of La Venta named “La Venta Fault” shows evidence of recent activity, corroborated also by GPS measurements (4–5 mm/year of sinistral motion). Assuming that during a probable earthquake the whole mapped length of this fault would rupture, it would produce an event of maximum moment magnitude Mw = 7.7. Even though only a few focal mechanism solutions indicate a stress regime relevant for reactivation of these strike-slip structures, we hypothesize that these faults are active and suggest two probable explanations: (1) these faults are characterized by long recurrence period, i.e., beyond the instrumental record, or (2) they experience slow slip events and/or associated fault creep. The analysis of focal mechanism solutions of small magnitude earthquakes in the upper plate, for the period between 1995 and 2008, revealed that frequent normal faults, sub-parallel to the trench, could be reactivated in the current stress field related to the Cocos subduction. Moreover, these features could also be reactivated by subduction megathrust earthquakes.

Riparian Phytodiversity Status of Pristine Bhilangana Valley of Garhwal Himalaya: An Undocumented Retrospective Hitherto

The present study was conducted for quantitative and qualitative characteristics of floristic diversity at the species level along environmental gradients of major and minor streams of the Bhilangana River in the Tehri District of Garhwal Himalaya. The stratified random sampling design was used for the study purpose. A total of 150 nested quadrats each with a size of 20 m×20 m for tree species and within each major plot, 5 m×5 m and 1 m×1 m sub plots were nested for shrubs and herbaceous species respectively. A total of 212 plant species belonging to 158 genera and 87 families were recorded. On the basis of important value index (IVI), Pinus roxburghii, Rhododendron arboreum, Quercus leucotricophora, Quercus semecarpifolia and Lyonia ovalifolia were dominant tree species within the entire basin area along the stream courses. The Shannon index and Simpson index values recorded for trees, shrubs and herbs were 2.64 (0.13), 1.04 (0.87) and 4.25 (0.019) respectively. This study provides comprehensive information on the species diversity of different vegetation life forms in the riparian zone of the Bhilangana valley.

Preliminary assessment of pseudo-total and bioavailable metals in depth in the sediment of Luíz Rau stream in Novo Hamburgo (RS).

The Luíz Rau stream is one of the main streams of Novo Hamburgo. In the stream industrial effluents are released from various sectors, from paint and adhesive industries, metallurgy and leather industry, besides receiving a large amount of domestic sewage. The emissions of these pollutants contribute to decrease water and sediment quality. Within this context, this study evaluated the conditions of the Luíz Rau stream bed sediments, with the determination of the metals like cadmium, lead, chromium and nickel, in depth. To perform the evaluation three points were chosen for sampling along the stream course. The sampling sites were identified as Point A, in Roselândia district and this corresponds to one of the springs and therefore considered as reference value, Point B, in Santo Afonso district being a midpoint of the stream, and Point C also located in Santo Afonso district, near the outfall in Rio dos Sinos river. Cadmium was not detected in any point. At the A and C points chromium was the metal observed in higher concentration in the sediment, up to 45.14 mg kg(-1) concentration. In the B point, the metal that was observed in the highest amount was nickel in the concentration of 20.69 mg kg(-1).

Application of Computional Fluid Dynamics for Study of the Occurrence of Aerodynamic Effect for its Application in the Construction of Electric Race Car

In this article the issues related to Computional Fluid Dynamics of the occurrence of innovative aerodynamic effect were presented. Analysis were performed to determine the occurrence of Kammback aerodynamic effect and its application in a shape of a body of the real racing car in order to minimize drag forces of the vehicle. For the analysis, ideal aerodynamic shapes were modeled, subsequently they were subjected to modifications which were used to determine the occurrence of effect. The basic modeled shape was the raindrop shape solid, which is generally regarded as the ideal shape in terms of aerodynamics. The result of analysis was compared with the drag values known from the literature. Afterwards changes in the shape of the base solid were made to verify and determine the optimum Kammback shape, selected from a set of possible solutions, in which the geometrical changes has the lowest difference of values of drag force and drag coefficientCx(Cd)in comparison to the basic raindrop shape. Results of the study were subjected to graphic analysis, especially the distribution of air pressure on the surface of a solid and in a virtual wind tunnel, distribution of the air velocity and the course of air streams around the shape. The results were used to design the body of electric race car. The main objective was to minimize the aerodynamic drag of the vehicle.