Polar wandering path for India during the Precambrian

Summary The recent radiometric dating on some Precambrian formations of India and the available paleomagnetic data have enhanced the possibility of deducing the Polar wander path for India during the remote past. The data indicate that India was in the northern hemisphere during the Precambrian times. This inference has also been substantiated by the paleoclimatic evidences.     

Land suitability analysis for maize production in Indonesia using satellite remote sensing and GIS-based multicriteria decision support system

GeoJournal - Maize is one of the potential crops can help in regional food production with self-sufficiency of foods in the drought prone areas of East Java in Indonesia. The purpose of this...     

Initiation process of debris flows on different slopes due to surface flow and trigger-specific strategies for mitigating post-earthquake in old Beichuan County, China

The 12 May 2008 Wenchuan earthquake (Ms 8.0) in China, produced an estimated volume of 28 × 10⁸ m³ loosened material, which led to debris flows after the earthquake. Debris flows are the dominant mountain hazards, and serious threat to lives, properties, buildings, traffic, and post-earthquake reconstruction in the earthquake-hit areas. It is very important to understand the debris flow initiation processes and characteristics, for designing debris flow mitigation. The main objective of this article is to examine the different debris flow initiation processes in order to identify suitable mitigation strategies. Three types of debris flow initiation processes were identified (designated as Types A, B, and C) by field survey and experiments. In “A” type initiation, the debris flow forms as a result of dam failure in the process of rill erosion, slope failure, landslide dam, or dam failure. This type of debris flow occurs at the slope of 10 ± 2°, with a high bulk density, and several surges following dam failure. “B” type initiation is the result of a gradual increase in headward down cutting, bank and lateral erosion, and then large amount of loose material interfusion into water flow, which increases the bulk density, and forms the debris flow. This type of debris flow occurs mainly on slopes of 15 ± 3° without surges. “C” type debris flow results from slope failures by surface flow, infiltration, loose material crack, slope failure, and fluidization. This type of debris flow occurs mainly on slopes of 21 ± 4°, and has several surges of debris flow following slope failure, and a high bulk density. To minimize the hazards from debris flows in areas affected by the Wenchuan earthquake, the erosion control measures, such as the construction of grid dams, slope failure control measures, the construction of storage sediment dams, and the drainage measures, such as construction of drainage ditches are proposed. Based on our results, it is recommend that the control measures should be chosen based on the debris flow initiation type, which affects the peak discharge, bulk density and the discharge process. The mitigation strategies discussed in this paper are based on experimental simulations of the debris flows in the Weijia, Huashiban, and Xijia gullies of old Beichuan city. The results are useful for post-disaster reconstruction and recovery, as well as for preventing similar geohazards in the future.     

Effects of layered heterogeneity in subsurface geologic materials on solute transport under field conditions: A case study from northeastern Iowa, USA

In the Cedar River watershed of northeastern Iowa, USA, water quality in 17 out of 20 private wells indicates that groundwater is contaminated with nitrate from agricultural leachates. In nine of the wells, nitrate concentration exceeds the US Environmental Protection Agency recommended maximum contaminant level (MCL) of 45umg/L (as NO3 ^m) for drinking purposes. Solute-transport investigations determined that the surficial loam sediments, the Quaternary sand and gravel deposits, and the glacial till deposits form layered heterogeneity in the subsurface. The resulting conductivity contrast causes a capillary barrier, thereby altering the mechanisms of vertical tracer movement. Storm-water tracing with potassium bromide, corn fertilizer, and fluorescein dye indicates that macropore flow occurs only within the upper 0.9um of loamy sediments. An average breakthrough concentration of 204umg/L bromide at 0.3um depth on day 3 after the storm event supports the hypothesis of macropore flow in the surficial soils. Fluorescein dye was recovered at a depth of 0.3um with a peak concentration of 650u7g/L at approximately 5udays after the storm event. The loamy sediment layer is underlain by the Iowan Pebble Band, a pebbly layer admixed with sand, developed in post-glacial time. In the field experiments, preferential flow of the tracers was predominantly vertical within the loamy sediments but rapidly changed to a horizontal matrix flow upon entering the materials of higher saturated hydraulic conductivity in the Pebble Band. The Pebble Band is underlain by low-conductivity deposits of pre-Illinoian till. Even though the upper oxidized portion of the glacial till is reported to have macropores, the Pebble Band prevented deeper infiltration of storm water by maintaining a strong component of horizontal hydraulic gradient. Chemical data indicate that the Pebble Band is a hydraulic-conductivity boundary that abruptly changes the unsaturated-flow mechanism from macropore flow to matrix flow. Résumé Dans le bassin de la rivière du Cèdre, au nord-est de l'Iowa (États-Unis), la qualité de l'eau de 17 puits particuliers sur 20 montre que l'eau souterraine est contaminée par des nitrates provenant de lessivages agricoles. Dans 9 de ces puits, la concentration en nitrates dépasse la concentration maximale recommandée par l'Agence américaine de protection de l'environnement (EPA), fixée à 45umguNO3/L pour l'eau potable. Des études sur le transport de solutés ont montré que les sédiments détritiques (loamy) superficiels, les dépôts quaternaires de sables et de graviers et les dépôts morainiques constituent une formation hétérogène litée sous la surface. Le contraste de conductivité résultant constitue une barrière capillaire qui modifie les mécanismes réglant le mouvement vertical du traceur. Le traçage de l'eau d'une averse par du bromure de potassium, un engrais du maïs et de la fluorescéine indique que l'écoulement dans les macropores se produit uniquement dans les premiers 90ucm des sédiments détritiques (loamy). Une concentration moyenne de la restitution de 204umg/L de bromure à 30ucm de profondeur le troisième jour après l'averse va dans le sens de l'hypothèse d'un écoulement dans les macropores des sols superficiels. La restitution de la fluorescéine s'est produite à 30ucm de profondeur par un pic à une concentration de 650u7g/L environ 5ujours après l'averse. La couche de sédiments détritiques est recouverte par la couche de galets de l'Iowa, un niveau postglaciaire de galets mêlés à du sable. Au cours des expériences de terrain, un écoulement préférentiel des traceurs a été verticalement prédominant dans les sédiments détritiques (loamy), mais s'est rapidement changé en un écoulement matriciel horizontal en entrant dans les matériaux à plus forte conductivité hydraulique saturée dans la couche de galets de l'Iowa. Cette couche de galets est recouverte (underlain) par des dépôts à faible conductivité de la moraine pré-illinoyenne. Même si la partie supérieure oxydée de la moraine paraît posséder des macropores, la couche à galets empêche l'infiltration de l'eau de l'averse en introduisant une forte composante dans le gradient hydraulique horizontal. Les données chimiques montrent que la couche à galets se présente comme une limite de conductivité hydraulique qui change brutalement le mécanisme d'écoulement non saturé d'un écoulement en macropore en un écoulement matriciel. Resumen Se ha detectado una contaminación por lixiviados de nitrato de origen agrícola en 17 de los 20 pozos particulares muestreados en la cuenca del río Cedar, al Nordeste de Iowa (EEUU). En nueve de los pozos, el contenido en nitrato es superior a la concentración máxima admitida para agua potable (45umg/L), de acuerdo con los criterios de la Agencia Medioambiental de los Estados Unidos (USEPA). Mediante investigaciones de transporte de solutos, se ha podido caracterizar la heterogeneidad del subsuelo debido al contraste de conductividad hidráulica entre las tres capas identificadas: sedimentos margosos superficiales, depósitos Cuaternarios de arena y grava, y depósitos de till glacial. El contraste de materiales origina una barrera capilar que altera los mecanismos del desplazamiento vertical de trazador. Se ha utilizado bromuro de potasio, fertilizante de maíz y fluoresceína como trazadores del agua de tormenta. De esta forma se ha observado que el flujo a través de macroporos es significativo únicamente en la capa superior margosa de 0.9um. Prueba de ello es que se registró una concentración promedio de 204umg/L de bromuro, a una profundidad de 0.3um, tres días después del episodio de lluvia. Se midió asimismo un pico de fluoresceína de 650u7g/L, también a 0.3um, al cabo de cinco días. Bajo las margas se encuentra el nivel de cantos rodados de Iowa (Iowan Pebble Band), desarrollado en un período post-glacial, que consiste en cantos rodados mezclados con arena. Gracias a los experimentos de campo se pudo comprobar que hay un flujo vertical preferente de trazador en el estrato superior margoso, el cual se convierte de inmediato en horizontal (en la matriz) al encontrar el nivel de cantos rodados, cuya conductividad hidráulica saturada es mayor. Por debajo de los cantos hay depósitos de tillita pre-Illinoiense de baja conductividad. Aunque se han identificado macroporos en la parte superior oxidada de los depósitos glaciales, la existencia de un marcado gradiente horizontal en el nivel de cantos rodados actúa impidiendo la infiltración del agua de tormenta. Los datos químicos indican que el nivel de cantos rodados se comporta como un contorno de conductividad hidráulica que altera abruptamente el mecanismo de flujo no saturado, inicialmente a través de los macroporos del suelo, para convertirlo en flujo en medio poroso.     

Forecasting flood risk in the Indus River system using hydrological parameters and its damage assessment

Hydrological parameters are among the widely used parameters in assessing flood risk. On the other hand, anticipated flood damages, in case of flooding, are estimated with the help of expected losses in areas nearer to the watercourse. The major source of almost every-year flooding in Pakistan is the Indus River system that comprises the major rivers of Pakistan. We first use observed data to construct simulated data models based on various probability distributions namely normal, lognormal, Weibull, largest extreme value, gamma-3, and log-Pearson type-3 distributions and thereby compute probable maximum flood. Secondly, we perform log-Pearson type-3 analysis with and without historic adjustment on the observed data series of 17 years to forecast floods with return periods T of 2, 5, 10, 25, 50, 100, and 200 years. We also categorize the river structures based on the risk of flooding. Lastly, we estimate risk of flood damages in terms of expected losses based on observed data. The present study reveals that the log-Pearson type-3 distribution is relatively better for estimating probable maximum flood. We use exceedence probability to assess the risk of flooding in the various structures of the said rivers. The analysis shows that flood damages in Pakistan may be reduced by increasing the design capacity of the structures and also by giving awareness to people about the flood-generating factors.     

GIS-based DRASTIC model for groundwater vulnerability and pollution risk assessment in the Peshawar District,Pakistan

Groundwater is the most economic natural source of drinking in urban and rural areas which are degraded due to high population growth and increased industrial development. We applied a GIS-based DRASTIC model in a populated urban area of Pakistan (Peshawar) to assess groundwater vulnerability to pollution. Six input parameters—depth to phreatic/groundwater level, groundwater recharge, aquifer material, soil type, slope, and hydraulic conductivity—were used in the model to generate the groundwater vulnerable zones. Each parameter was divided into different ranges or media types, and ratings R?=?1?–?10 were assigned to each factor where 1 represented the very low impact on pollution potential and 10 represented very high impact. Weight multipliers W?=?1?–?5 were also used to balance and enhance the importance of each factor. The DRASTIC model scores obtained varied from 47 to 147, which were divided into three different zones: low, moderate, and high vulnerability to pollution. The final results indicate that about 31.22, 39.50, and 29.27% of the total area are under low, moderate, and high vulnerable zones, respectively. Our method presents a very simple and robust way to assess groundwater vulnerability to pollution and helps the decision-makers to select appropriate landfill sites for waste disposals, and manage groundwater pollution problems efficiently.     

Number Counts,Confusion, Mapping Issues,and Sky Coverage Analysis for Radio Continuum Surveys through Emu Early Science,EMU-ASKAP,and WODAN Especially for Cosmology Science Goals

In this study, we discuss the challenges radio astronomers face while observing radio continuum sources. We consider issues related to rms noise, confusion, position accuracy, shot noise and how these issues affect observation results, data analysis and the science goals we are trying to achieve. We mainly focus on the Evolutionary Map of the Universe (EMU-ASKAP) sky survey, EMU Early science survey and Westerbork Observations of the Deep APERTIF Northern sky (WODAN). The study will also be useful for future surveys like with possible continuum surveys through MeerKAT (e.g., MIGHTEE) and SKA-1. The late time Integrated Sachs-Wolfe (ISW) effect detection is one of the major areas of research related to dark energy cosmology. We will particularly discuss how technical, data analysis and mapping issues, affect galaxy over/under density dependent science goals like the detection of the late time Integrated Sachs-Wolfe (ISW) effect through wide-field radio continuum surveys.

     

Snowmelt runoff assessment and prediction under variable climate and glacier cover scenarios in Astore River Basin,Western Himalayas

Climate change is expected to have a significant impact on the Himalayan region, which may ultimately affect the water security and agriculture productivity in the region. Investigations of hydrologic regimes and their linkage to climatic trends are therefore gaining importance to reduce vulnerability of growing implications in the region. In the present study, the eWater source software implementation of GR4JSG snow melt model was used for snow melt runoff modeling of the Astore river basin, western Himalayas. The model calibration and validation indicated a close agreement between the simulated and observed discharge data. The scenario of 0.9 °C increase in temperature indicated 33% rise in the river discharge, while an increase of 10% in precipitation may exaggerate the river flows by 15%. The scenario of 100% increase in glaciated area showed 41% increase in the Astore river discharge. On the other hand, reduction of 50% glacier cover may result in 34% decline in the river discharge, while 0% glacier coverage may reduce the river discharges by 49% from that of the base year 2014. It is essential to develop a long-term water resource monitoring process and adapt water management systems taking into account the socio-economic and ecological complexities of the region.     

Comparative study of body composition of four fish species in relation to pond depth

Fish specimen of Labeo rohita, Cirrhinus mrigala, Hypophthalmicthys molitrix and Catla catla were sampled from three ponds of different depths (152 cm, 122 cm and 76 cm) to compare the body composition of these species in relation to pond depth. There was significant (P < 0.001) effect of pond depth on water, ash, organic, fat and protein contents (all % wet and dry body weight). It was observed that pond depth has significant effect (P < 0.01) on condition factor in pond B (122 cm depth) and no effect in pond A and C. Maximum mean values of body composition were observed in Labeo rohita in all the three ponds. Present study demonstrates that fish cultured in ponds of different depths have different values of protein which can help guide the farmers to select best pond depths to produce protein rich fish.     

Debris flow susceptibility analysis based on the combined impacts of antecedent earthquakes and droughts: a case study for cascade hydropower stations in the upper Yangtze River,China

The upper Yangtze River region is one of the most frequent debris flow areas in China. The study area contains a cascade of six large hydropower stations located along the river with total capacity of more than 70 million kilowatts. The purpose of the study was to determine potential and dynamic differences in debris flow susceptibility and intensity with regard to seasonal monsoon events. We analyzed this region’s debris flow history by examining the effective peak acceleration of antecedent earthquakes, the impacts of antecedent droughts, the combined effects of earthquakes and droughts, with regard to topography, precipitation, and loose solid material conditions. Based on these factors, we developed a debris flow susceptibility map. Results indicate that the entire debris flow susceptibility area is 167,500 km², of which 26,800 km² falls within the high susceptibility area, with 60,900 km² in medium and 79,800 km² are in low susceptibility areas. Three of the six large hydropower stations are located within the areas with high risk of debris flows. The synthetic zonation map of debris flow susceptibility for the study area corresponds with both the investigation data and actual distribution of debris flows. The results of debris flow susceptibility provide base-line data for mitigating, assessing, controlling and monitoring of debris flows hazards.