Centripetal Drainage Research Articles

A Novel Method to Identify Radial Drainage Based on Morphological Features

The automatic detection and accurate characterization of drainage patterns are of primary importance for interpreting the regional geologic origin and the features of the regional geological structure. However, there are few studies regarding the identification of cross-basin drainage patterns. In addition, the automatic level of the current approaches needs to be further improved. As a typical type of cross-basin drainage pattern, radial drainage (RD) has unique spatial morphological features: diverging from the center to the surrounding area, developing in adjacent sections of multiple basins, and having a number of source nodes that is not smaller than the number of its outlet nodes. Based on these morphological features, this study aims to develop a novel method for automatic identification of RD using a feature-matching algorithm. The experiment in Mount Lu demonstrates that the proposed method was efficient in RD identification. In this study area, the RDs were identified, and there were no false or missed judgments, which was verified through experts. The proposed method not only helps to detect cross-basin drainage patterns, RD, and centripetal drainage but also has a unique advantage in identifying geographical scenes with complex spatial structures.

Mechanism of removal and retention of heavy metals from the acid mine drainage to coastal wetland in the Patagonian marsh

The attenuation of the acid mine drainage is one of the most important environmental challenges facing the mining industry worldwide. Mining waste deposits from an ancient metallurgical extraction of heavy metals were found near to the San Antonio marsh in Patagonia. The aim of this work was to determinate which mechanisms regulate the mobilization and retention of metals by acid drainage. A geological and geomorphological survey was carried out and samples from the mining waste deposits and the marsh were collected to determine soil texture, Eh pH, organic matter, Cu, Pb, Zn and Fe content, and soil mineralogical composition. Metals in marsh plants were determined in above- and below-ground structures. In the mining waste deposits polymetallic sulphides were recognized where the oxidation and formation of oxy-hydroxides and sulphates of Fe, Cu, Pb and Zn occurs. Then, by the alteration of those minerals, the metals enter in solution and are mobilized with the surface drainage towards the marsh where adsorption in the soils fine fraction and organic matter and/or by plants occurs. Locally, in the mining waste deposits, the precipitation/dissolution of Cu, Pb, and Zn sulphates take place in small centripetal drainage basins. In topographically lower portions of the marsh desorption and removal of metals by tidal flow could also be happen. The results allow to concluding that the marsh adjacent to the mining waste deposits is a geochemically active environment that naturally mitigates the contamination caused by acid drainage.

Uranium-Bearing Magnesian-Calcrete in Surficial Environment from Khemasar, Churu District, Rajasthan, India

Magnesium-bearing calcretes of soft-gritty and hard pan varieties containing uranium concentrations from 16 to 74 ppm with <10 ppm of thorium are located along the Saraswati palaeochannel at Khemasar village, Churu district, Rajasthan. The uraniumbearing calcretes are exposed over an areal extent of 300 m × 200 m with thickness of up to 2 m in an interdunal depression. The silty sand layer occurring below the calcrete horizon suggests that it is a valley-fill calcrete, deposited along a palaeochannel. This occurrence of uraniferous Mg-calcrete in the Saraswati river palaeochannel opens up a large area for uranium exploration in the calcrete environment of Thar Desert. These calcretes are composed of 15.94% to 25.39% CaO, 7.15% to 22.39% MgO and Sr/Ba ratio up to 66.98. There is a positive correlation of U with Sr/Ba and MgO. The high Sr/Ba ratio and MgO indicate water of saline nature and high rate of evaporation. Ephemeral centripetal drainage mixing with the dissected palaeochannel waters and groundwaters, under arid climatic conditions might have resulted in the formation of this kind of uranium-bearing calcrete in fluvio-lacustrine environment.

Fluid Flow along Venous Adventitia in Rabbits: Is It a Potential Drainage System Complementary to Vascular Circulations?

BackgroundOur previous research and other studies with radiotracers showed evidence of a centripetal drainage pathway, separate from blood or lymphatic vessels, that can be visualized when a small amount of low molecular weight tracer is injected subcutaneously into a given region on skin of humans. In order to further characterize this interesting biological phenomenon, animal experiments are designed to elucidate histological and physiologic characteristics of these visualized pathways.MethodsMultiple tracers are injected subcutaneously into an acupuncture point of KI3 to visualize centripetal pathways by magnetic resonance imaging or fluorescein photography in 85 healthy rabbits. The pathways are compared with venography and indirect lymphangiography. Fluid flow through the pathways is observed by methods of altering their hydrated state, hydrolyzing by different collagenases, and histology is elucidated by optical, fluorescein and electron microscopy.ResultsHistological and magnetic imaging examinations of these visualized pathways show they consist of perivenous loose connective tissues. As evidenced by examinations of tracers’ uptake, they appear to function as a draining pathway for free interstitial fluid. Fluorescein sodium from KI3 is found in the pathways of hind limbs and segments of the small intestines, partial pulmonary veins and results in pericardial effusion, suggesting systematical involvement of this perivenous pathway. The hydraulic conductivity of these pathways can be compromised by the collapse of their fiber-rich beds hydrolyzed by either of collagenase type I, III, IV or V.ConclusionsThe identification of pathways comprising perivenous loose connective tissues with a high hydraulic conductivity draining interstitial fluid in hind limbs of a mammal suggests a potential drainage system complementary to vascular circulations. These findings may provide new insights into a systematically distributed collagenous connective tissue with a circulatory function and their potential relevance to the nature of acupuncture meridians.

Desert Depressions (Khabrat ) in the Iraqi Hamad and their possibility for water Harvesting

This study aim to find out the geographyical characteristics of the desert depressions in Iraqi Hamad and their possibilities for water harvesting ,by using satellite data and geographic information systems ( Arc GIS 9.3) .The study area is located between the latitude of 32º 5´ to 33º 39´ North and the longitude of 38º 47´ to 39º 41´ East ,in the northern –western of Iraqi western plateau . There are 22 depressions in area under study , their areas are between 0,149138 km² as in Uniza depression to 3.120135 km² for Kharjah depression . These depressions are different in capacity of water harvesting ,Kharjah has capacity of 6240270 m³ , while Uniza has no more than 149138 m³.The capacity of al- Ghatia depression is 2100277 m³, less than the water comes from its catchment area 3743191 m³ as is estimated by researcher according to the method of Snyder . Depressions are created by solution of lime stone and other helping agents and processing such as wind ( deflation ) ,lineaments ,and geological formations. Some of the depressions have centripetal drainage pattern and their shapes are near to the circle shape as well as other features , so these depressions are suitable for water harvesting .

Stream channel network analysis applied to colony-wide feeding structures in a Permian bryozoan from Greenland

Colony-wide feeding currents are a common feature of many bryozoan colonies. These feeding currents are centered on excurrent macular chimneys that expel previously filtered water away from the colony surface. In some bryozoans these macular chimneys consist of a branching channel network that converges at a point in the center of the chimney. The bifurcating channels of the maculae are analogous to a stream channel network in a closed basin with centripetal drainage. The classical methods of stream channel network analysis from geomorphology are here used to quantitatively analyze the number and length of macular channels in bryozoans. This approach is applied to a giant branch of the trepostome bryozoanTabuliporafrom the Early Permian Kim Fjelde Formation in North Greenland. Its large size allowed 18 serial tangential peels to be made through the 8-mm-thick exozone. The peels intersected two stellate maculae as defined by contiguous exilapores. The lengths of 1460 channels radiating from the maculae were measured and their Horton-Strahler stream order and Shreve magnitude scored.We hypothesize that if fossil bryozoan maculae function as excurrent water chimneys, then they should conform to Horton's laws of stream networks and behave like closed basins with centripetal drainage. Results indicate that the stellate maculae in this bryozoan behaved liked stream channel networks exhibiting landscape maturation and stream capture. They conformed to the Law of Stream Number. They have a Bifurcation Ratio that falls within the range of natural stream channel networks. They showed a pattern opposite that expected by the Law of Stream Lengths in response to behavior characteristic of a centripetal drainage pattern in a closed basin. Thus, the stellate maculae in this bryozoan probably functioned as excurrent water chimneys with the radiating channels serving to efficiently collect the previously filtered water, conducting it to the central chimney for expulsion away from the colony surface.

Erosional modification and gully formation at Meteor Crater, Arizona: Insights into crater degradation processes on Mars

Hydrogeological modification of Meteor Crater produced a spectacular set of gullies throughout the interior wall in response to rainwater precipitation, snow melting, and possible groundwater discharge. The crater wall has an exceptionally well-developed centripetal drainage pattern consisting of individual alcoves, channels, and fans. Some of the gullies originate from the rim crest and others from the middle crater wall where a lithologic transition occurs; broad gullies occur along the crater corner radial faults. Deeply incised alcoves are well developed on the soft Coconino Sandstone exposed on the middle crater wall, beneath overlying dolomite. In general, the gully locations are along crater wall radial fractures and faults, which are favorable locales of erosion due to preferential rock breakup from faulting, and groundwater flow/discharge; these structural discontinuities are also the locales where the surface runoff from rain precipitation and snow melting can preferentially flow, causing erosion and crater degradation. Channels are well developed on the talus deposits and alluvial fans on the periphery of the crater floor. Caves exposed on the lower crater level point to percolation of surface runoff and selective discharge through fractures on the crater wall. In addition, lake sediments on the crater floor provide significant evidence of a past pluvial climate, when the water table was higher, and groundwater may have seeped from springs on the crater wall. Although these hydrological processes continue at Meteor Crater today, conditions at the crater are much more arid than they were soon after impact, reflecting a climatic shift. This climate shift and the hydrological modifications observed at Meteor Crater provide insights for landscape sculpturing on Mars during various parts of its history.

Lacustrine sediments provide geochemical evidence of environmental change during the last millennium in southeastern Brazil

A 172 cm-long sediment core was collected from a small pristine lake situated within a centripetal drainage basin in a tropical karst environment (Ribeira River valley, southeastern Brazil) in order to investigate the paleoenvironmental record provided by the lacustrine geochemistry. Sediments derived from erosion of the surrounding cambisoils contain quartz, kaolinite, mica, chlorite and goethite. Accelerator mass spectroscopy (AMS) 14C dating provided the geochronological framework. Three major sedimentary units were identified based on the structure and color of the sediments: Unit III from 170 to140 cm (1030±60–730±60 yr BP), Unit II from 140 to 90 cm (730±60–360±60 yr BP) and Unit I from 90 to 0 cm (360±60–0 yr BP). Results of major and trace element concentrations were analysed through multivariate statistical techniques. Factor analysis provided three factors accounting for 72.4% of the total variance. F1 and F2 have high positive loadings from K, Ba, Cs, Rb, Sr, Sc, Th, light rare earth element (LREE), Fe, Cr, Ti, Zr, Hf and Ta, and high negative loadings from Mg, Co, Cu, Zn, Br and loss on ignition (LOI). F3, with positive loadings from V and non-metals As and Sb, accounts for a low percentage (9.7%) of the total variance, being therefore of little interpretative use. The profile distribution of F1 scores reveals negative values in Units I and III, and positive values in Unit II, meaning that K, Ba, Cs, Rb, Sr, Sc, Th, LREE, Fe, Cr, Ti, Zr, Hf and Ta are relatively more concentrated in Unit II, and Mg, Co, Cu, Zn and Br are relatively more abundant in Units I and III. The observed fluctuations in the geochemical composition of the sediments are consistent with slight variations of the erosion intensity in the catchment area as a possible response to variations of climatic conditions during the last millennium.

The History and Nature of Wind Erosion in Deserts

Recently, the importance of wind erosion has been reevaluated. Many low-angle surfaces, developed on susceptible materials, possess closed depressions (pans), and these often have a distinctive morphology and lunette dunes on their lee sides. It has also become apparent that in drylands there are extensive areas of stone pavements, some of which have been molded by deflation; however, it is now recognized that other horizontal sorting processes have played a role, especially movement of fines by overland flow. Vertical sorting associated with wetting and drying, salt heave, bioturbation, frost action, and dust accretion have also played a role. In hyperarid areas, especially with unidirectional winds, bedrock outcrops and old lake beds have been molded to give aerodynamic forms, called yardangs. The study of dust storms by analysis of climatological data and remote sensing has revealed the importance of deflation, especially in hyperarid areas with centripetal drainage. Deflation hot spots, such as the Bodélé Depression, have been identified. Analysis of ice and ocean cores and loess deposits has indicated that wind activity was greater during glacial phases than now. There is, however, great variability in the importance of wind at the present day, depending on the wind velocity characteristics of different deserts.

Geological evolution of the Tyras Vallis paleolacustrine system, Mars

Using the new High Resolution Stereo Camera (HRSC) data and other Martian data sets, we reconstructed the hydrological history of an unnamed complex crater in the Xanthe Terra region. The crater hosted a lacustrine basin fed by a dense and centripetal drainage system, developed along its inner rim, and by the Tyras Vallis channel. Where the Tyras Vallis opens into the crater, a prominent delta‐like feature is visible, characterized by a central terrace and two small longitudinal scarps. This deposit has been used as sedimentary recorder of the crater lake history and allowed assessment of the overall hydrological evolution. Two major stands of the water level have been inferred at 700 and 550 m above the crater floor, based on the correlation between the morphology and topography of the fan and the crater floor deposits. Our reconstruction reveals a complex sedimentary evolution of the fan, which underwent deltaic and alluvial sedimentation, as a result of the different lake water levels and Tyras Vallis supplies. A dominant erosional evolution of the fan‐delta was determined by the interaction between the fluvial characteristics and basin wave regime. Wave height analysis and morphological comparison with terrestrial analogues support this hypothesis. The lacustrine activity could be chronologically placed between the Late Noachian and the Hesperian. The climatic conditions could have allowed the recharge of the regional groundwater system by precipitation and episodic fluvial activity. However, also heating effects of cratering could have affected the system, rejuvenating or accelerating the recharge of the local aquifer.

Use of morphostructural analysis to show halokinesis during Mio-Plio-Quaternary in the South-West part of Aquitain Basin

In the South Aquitain sector, salt bodies of varying sizes present two geographical gradients. The first gradient, south to north, associated with the proximity of the Pyrenees shows a decreasing deformation of the structures towards the north. The second gradient explains their increasing depth of burial from the west (extrusive structures) to the east (intrusive structures). This organization has been studied from the western sector (Tercis-Benesse and Bastennes-Louer) to the eastern sector (Viella-Labarthete and Nogaro-Lussagnet). Other more modest structures, revealed by hydrographical anomalies, illustrate halokinetic events during the Quaternary. Then the detailed study of the Geaune dome shows a neotectonic phenomenon dating from the Mio-Pliocene. The radial annular drainage pattern of this structure is guided by recurrent faulting during the Quaternary. Thus the halokinetic dynamics consist in three phases: deformation of the diapirs (overthrusts) during the Oligocene, resuming of halokinesis during the middle of the Miocene and recurrent faulting during the Riss. A model of geomorphological evolution of the domes is then proposed. The first phase (stages of positive relief) is characterized by the centrifugal drainage pattern of the dome. The second phase (stages of inverted relief) is distinguished by the erosion of the center of the structure, by an inversion of the drainage pattern and by the sedimentary accretion in the central depression.

Uma possível estrutura de impacto de meteorito em Ubatuba, litoral norte de São Paulo

Various meteoritic impact craters have been discovered on the surface of the Earth in the last few decades. At least six such structures are known in Brazil. This paper briefly describes a possible impact crater (1 km in diameter) in the Ubatuba region, northern seashore of Sao Paulo. Geomorphological and geological characteristics suggestive of a meteoritic impact for this structure include: almost circular shape; half-moon rim with steep slopes; topographic relief relative to adjacent alluvial plain; centripetal drainage partem; close association between native vegetation and fine sediments that fill the structure.

Drainage pattern and its distribution in the Kathmandu valley

Drainages in the Kathmandu Valley traverse the hills made up of metasedimentary rocks and Sheopuri Injection Gneiss, and the plains of fluvio-lacustrine sediments. As the streams cut into the underlying rocks and structures of the region, they give rise to certain drainage arrangement seven types of drainage patterns are identified in the valley. They are Dendritic, Rectangular, Trellis, Sub-parallel, Barbed, Radial and Centripetal. The Kathmandu Valley as a whole is a centripetal drainage pattern and the other drainage patterns are distributed in different tributaries within the valley.

Morphometric analysis of the Bagmati river in Kathmandu valley

The oval shaped Kathmandu valley stretches 30 km E-W and 25 km in N-S direction encompasing an area of about 647 sq. km. The valley is drained by 10 different tributaries of the Bagmati river forming a typical Centripetal drainage system. The drainages consisting of Dhobi khola from Shivapuri Range, Bishnumati khola from Shivapuri and Nagarjung ranges, Hanumante and Manohara kholas from Nagarkot range, Nakhu, Kodku and Godawari Kholas from Phulchowki range and Balkhu and Bosan kholas from Chandragiri range, have originated from different directions. Bagmati, Dhobi, Balkhu and Bosam kholas form the 4th order network whereas the remaining drainages form the 5th order network and the Kathmandu Valley as a whole is taken into the 6th order network.

Cerebral venous angiomas: MR findings.

Seven patients with suspected cerebral venous angioma studied by either CT or angiography were imaged with magnetic resonance. Six of seven cases demonstrated a stellate appearance on contrast enhanced CT. In two patients this finding was verified by angiography. Flow void was identified on both T1- and T2-weighted pulse sequences. In one patient a field echo sequence demonstrated high intensity signal within the venous angioma. Magnetic resonance proved superior to CT in the identification of these lesions. A stellate configuration with an emanating transcortical vein and centrifugal drainage (transcortical venous flow) from the angioma into a sinus was present in all cases. Centripetal drainage via thalamostriate and internal cerebral veins was not seen. There was no evidence of mass effect, scar, or hemorrhage. Four of the angiomas were located in a frontal lobe and three in a cerebellar hemisphere. This distribution of the lesions is similar to that reported in the literature in which the frontal lobe is the most common location followed by the cerebellar hemisphere. An embryological explanation is cited and supported by a review of the literature.