The analysis of using satellite soil moisture observations for flood detection,evaluating over the Thailand’s Great Flood of 2011

Natural Hazards - A flood monitoring and warning system provides critical information that can protect property and save lives. A basin-scale flood monitoring system requires an effective...     

Simulation of tornado over Orissa (India) on March 31, 2009, using WRF–NMM model

A severe thunderstorm produced a tornado (F3 on the Fujita-Pearson scale), which affected Rajkanika block of Kendrapara district of Orissa in the afternoon of March 31, 2009. The devastation caused by the tornado consumed 15 lives and left several injured with huge loss of property. The meteorological conditions that led to this tornado have been analyzed. An attempt is also made to simulate this rare event using Non-hydrostatic Mesoscale Model (NMM) core of the Weather Research and Forecasting (WRF) system with a spatial resolution of 4 km for a period of 24 h, starting at 0000 UTC of March 31, 2009. The atmospheric settings resulted from synoptic, surface, upper air, satellite and radar echo studies were favorable for the occurrence of a severe thunderstorm activity over Rajkanika. The model-simulated meteorological parameters are consistent with each other, and all are in good agreement with the observation in terms of the region of occurrence of the intense convective activity. The model has well captured the vertical motion. The core of the strongest winds is shown to be very close to the site of actual occurrence of the event. The wind speed is not in good agreement with the observation as it has shown the strongest wind of only 20 ms⁻¹, against the estimated wind speed of 70 ms⁻¹. The spatial distributions as well as intensity of rainfall rates are in good agreement with the observation as model simulated 35.4 mm against the observed rainfall of 41 mm over Chandbali. The results of these analyses demonstrated the capability of high-resolution WRF–NMM model in simulation of severe thunderstorm events.     

Study of subsurface structures using seismic reflection data for Kalar–Khanaqin area/Kurdistan region,Iraq

The study is carried out to detect the subsurface structures that have geological and economic importance by interpreting the available seismic reflection data of an area estimated to be about 1,752 km². The study comprises of the Kalar–Khanaqin and surrounding area, which is located at Zagros folded zone. Twenty-five seismic sections had been interpreted. The total length of all the seismic lines is about 650.4 km. Interpretation of the seismic data is focused on two reflectors, lower Fars and Jeribe formation. The lower Fars reflector picked at the two-way time ranging from 0.1 to 2.6 second, while the Jeribe reflector picked at the two-way time ranging from 1.0 to 2.7 second. The constructed maps denote to the existence of many closed and nose structures, in addition, to numerous fault types. All these features were detected in the area having the NW–SE trend. The depth of the lower Fars formation is ranging from 100.0 to 4,800.0 m, while the depth of the Jeribe formation is ranging from 1,700.0 to 5,000.0 m. The depth maps for the two formations also refer to the similarity of the major geological structures. These structures appear in both formations with existence of slight variation in dimensions. The closed structure no. (1) is located at the north of the study area. The nose structure no. (2) is located at the south of the area. At the west of the area, the elongated structure no. (3). The longitudinal reveres fault intersects the SW limb of the structure. The SW limb of elongated structure no. (4), intersect by longitudinal reveres fault, is located at the east of the area. There is also the semi-closed structure no. (5), which appears at the west of the area around the Qr-1 well. Most of detected faults are of reverse and thrust types having a variable amount of throws and horizontal displacements. Some seismic sections explained the existence of the decollement surface within lower Fars formation, which caused the thrusting and faulting of the overlaying beds.     

Application of spectrum–area fractal model to identify of geochemical anomalies based on soil data in Kahang porphyry-type Cu deposit,Iran

The aim of this study is to identify geochemical anomalies using power spectrum–area (S–A) method based on the grade values of Cu, Mo and Au in 2709 soil samples collected from Kahang porphyry-type Cu deposit, Central Iran. S–A log–log plots indicated that there are three stages of Cu, Mo and Au enrichment. The third enrichment was considered as the main stage for the presence of Cu, Mo and Au at the concentrations above 416 ppm, 23 ppm and 71 ppb, respectively. Elemental anomalies are positively associated with monzo–granite–diorite and breccias units which are in the central and western parts of the deposit. The anomalies are located within the potassic, phyllic and argillic alteration types and also there is the positive correlation between the anomalies and nearing faults in the studied area. The results obtained via fractal model were interpreted accordingly to incorporate the information for the mineralized areas including detailed geological map, structural analysis and alterations. The results show that S–A multifractal modeling is applicable for anomalies delineation based on soil data.     

Analysis of urban growth using Landsat TM/ETM data and GIS—a case study of Hyderabad, India

Hyderabad is one of the fastest growing mega cities in India and it is facing many economic, social and environmental problems due to rapid urban growth. For the better planning of resources and to provide basic amenities to its residents, it is necessary to have sufficient knowledge about its urban growth activities. Also, it is necessary to monitor the changes in land use over time and to detect growth activities in different parts of the city. To accomplish these tasks with greater accuracy and easiest way, remote sensing and geographic information system (GIS) tools proved to be very advantageous. This study makes an attempt towards the mapping of land use classes for different time periods and analysis of apparent changes in land use using the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) data for the urban agglomeration of Hyderabad, India. In this study, three different time periods viz. 1989–2000, 2000–2005 and 2005–2011 are chosen for the analysis. The results have shown that high-density urban area had grown during 1989–2011 by encroaching into other land use classes. The urban growth has also affected water resources both, qualitatively and quantitatively in the region. The transformation of other land use types into urban area dynamically continued in the North-East and Southern parts of the city. In the North-East direction, the urban growth was mostly due to growth in industrial and residential area and in Southern part, mostly due to residential growth.     

Real-time prediction of a severe cyclone ��Jal�� over Bay of Bengal using a high-resolution mesoscale model WRF (ARW)

Real-time predictions for the JAL severe cyclone formed in November 2010 over Bay of Bengal using a high-resolution Weather Research and Forecasting (WRF ARW) mesoscale model are presented. The predictions are evaluated with different initial conditions and assimilation of observations. The model is configured with two-way interactive nested domains and with fine resolution of 9?km for the region covering the Bay of Bengal. Simulations are performed with NCEP GFS 0.5° analysis and forecasts for initial/boundary conditions. To examine the impact of initial conditions on the forecasts, eleven real-time numerical experiments are conducted with model integration starting at 00, 06, 12, 18 UTC 4 Nov, 5?Nov and 00, 06, 12 UTC 6 Nov and all ending at 00 UTC 8 Nov. Results indicated that experiments starting prior to 18 UTC 04 Nov produced faster moving cyclones with higher intensity relative to the IMD estimates. The experiments with initial time at 18 UTC 04 Nov, 00 UTC 05 Nov and with integration length of 78?h and 72?h produced best prediction comparable with IMD estimates of the cyclone track and intensity parameters. To study the impact of observational assimilation on the model predictions FDDA, grid nudging is performed separately using (1) land-based automated weather stations (FDDAAWS), (2) MODIS temperature and humidity profiles (FDDAMODIS), and (3) ASCAT and OCEANSAT wind vectors (FDDAASCAT). These experiments reduced the pre-deepening period of the storm by 12?h and produced an early intensification. While the assimilation of AWS data has shown meagre impact on intensity, the assimilation of scatterometer winds produced an intermittent drop in intensity in the peak stage. The experiments FDDAMODIS and FDDAQSCAT produced minimum error in track and intensity estimates for a 90-h prediction of the storm.     

Impact of data assimilation in simulation of thunderstorm (squall line) event over Bangladesh using WRF model,during SAARC–STORM Pilot Field Experiment 2011

Natural Hazards - A widespread thunderstorm (squall line or multicell line) occurred over Bangladesh on 11 May 2011 during 0300 UTC to 1300 UTC. A north–south oriented well-established squall...     

Interpretation of aero-magnetic data and satellite imagery to delineate structure — a case study for uranium exploration from Gwalior Basin,India

The Paleo-Meso Proterozoic Gwalior basin (E - W), lying to NW fringe of Bundelkhand massif is represented by litho-package of lower arenaceous Par Formation and upper chemogenic Morar Formation. It is bounded by Indo-Gangetic alluvium in north and east, Kaimur sediments in west and Bundelkhand granitoids in south. Gwalior Basin has been the exploration target for uranium mineralization right from early 60’s. Surface radioactivity anomalies due to uranium has been reported in both Par and Morar Formations of Gwalior Group and Vindhyan sediments. Besides presence of syngenetic uranium in the system, presence of post-depositional faults and fractures are the favorable factors. Aeromagnetic survey was carried out by AMD in 2002 with N-S lines of 500 m interval covering 9406 line km. The data with sampling interval of 0.1 sec was corrected for spikes, diurnal variation, IGRF, heading and lag. Final processed images are prepared after suitable leveling and gridding. First vertical derivative of TMI-RTP and tilt-angle derivative images are used to map the litho-contacts, lineaments and structural features. Numerous NE-SW trending low amplitude and NW-SE trending high amplitude magnetic linears corroborate with quartz reefs and basic dykes respectively. Besides, E-W to WNW-ESE and ENE-WSW trending fractures are also evident from the processed image maps. Further, the Euler’s depth solution of gridded aeromagnetic data calculated for structural indices of 0 and 1 are very consistent in locating the position of the causative sources. Based on the amplitude and textural character of processed aeromagnetic data, alteration zone is delineated well within the Morar Formation. Enhanced Thematic Mapper (ETM+) image with 30m resolution was merged with IRS PAN 1D (5.8 m resolution) for better spatial/radiometric resolution to extract litho-contacts and lineament patterns. Merged PAN band-4 after linear contrast and edge enhancement techniques deciphered detailed lineament pattern, which corroborate the magnetic data. Merged ETM+ (RGB 751) and PC (PC1-PC2-PC5) images depict litho-logical contrast. Integration of aeromagnetic and satellite imagery data helped in understanding the structural fabric of the Gwalior Basin and to identify favorable loci of uranium mineralization.     

The measurement of soil gases and shallow temperature for determination of active faults in a geothermal area: a case study from Ömer–Gecek,Afyonkarahisar (West Anatolia)

Afyonkarahisar is a very important geothermal province of western Anatolia and has low and medium enthalpy geothermal areas. This study has been carried out for the preparation of distribution maps of soil gases (radon and carbon dioxide) and shallow soil temperature and the exploration of permeable tectonic regions associated with geothermal systems and reveal the origins of radon and carbon dioxide gases. The western district of the study area is characterized by the high radon concentration (168.30 kBq/m³), carbon dioxide ratio (0.30%), and soil temperature (21.0 °C) values. Fethibey and Demirçevre faults, which allow the circulation of geothermal fluids, have been detected in the distribution maps of radon, carbon dioxide, and shallow depth temperature and the directions of the curves in these maps correspond to the strikes of Demirçevre faults. The effect of the fault plays an important role in the change of carbon dioxide concentration along the W-E directional geological section prepared to determine the change of soil gas and shallow depth temperature values depending on lithological differences, fault existence, and geothermal reservoir depth. On the other hand, it was determined that Rn²²² concentration and soil temperature changed as a function of geothermal reservoir depth or lithological difference. Tuffs in Köprülü volcano-sedimentary units are the main source of radon due to their higher uranium contents. Besides, the carbon dioxide in Ömer–Gecek soils has geothermal origin because of the highest carbon dioxide content (99.3%) in non-condense gas. The similarities in patterns of soil temperature, radon, and carbon dioxide indicate that the variation in soil temperatures is related to radon and carbon dioxide emissions. It is concluded that soil gas and temperature measurements can be used to determine the active faults in the initial stage of geothermal exploration successfully.     

Demarcation of inland vessels’ limit off Mormugao port region,India: a pilot study for the safety of inland vessels using wave modelling

The Ministry of Shipping desires to revise the inland vessels’ limit (IVL) notification based on scientific rationale to improve the safety of vessels and onboard personnel. The Mormugao port region extending up to the Panaji was considered for this pilot study. Measured winds and wave parameters (AWS and moored buoy) as well as NCEP re-analysis and NCMRWF winds were used for the analysis and input to regional and local models. The results of wave model were validated with measured significant wave heights (SWHs) and the comparison shows a good match. The analysis indicates that SWHs do not exceed 2.0 m during non-monsoon months, and in monsoon months exceed 5.0 m, and even 7.0 m, especially during extreme events. In order to draw IVL contours for Goa coastal region, local model was set up and nearshore waves were simulated for the period May 2004–May 2005. Based on the nearshore SWH distribution, IVL contours have been fixed for the Mormugao port and Panaji coastal regions.     

Accuracy analysis of the 2014–2015 Global Shuttle Radar Topography Mission (SRTM) 1 arc-sec C-Band height model using International Global Navigation Satellite System Service (IGS) Network

Global Shuttle Radar Topography Mission (SRTM) data products have been widely used in Earth Sciences without an estimation of their accuracy and reliability even though large outliers exist in them. The global 1 arc-sec, 30 m resolution, SRTM C-Band (C-30) data collected in February 2000 has been recently released (2014–2015) outside North America. We present the first global assessment of the vertical accuracy of C-30 data using Ground Control Points (GCPs) from the International GNSS Service (IGS) Network of high-precision static fiducial stations that define the International Terrestrial Reference Frame (ITRF). Large outliers (height error ranging from –1285 to 2306 m) were present in the C-30 dataset and 14% of the data were removed to reduce the root mean square error (RMSE) of the dataset from ～187 to 10.3 m which is close to the SRTM goal of an absolute vertical accuracy of RMSE ～10 m. Globally, for outlier-filtered data from 287 GCPs, the error or difference between IGS and SRTM heights exhibited a non-normal distribution with a mean and standard error of 6.5 ± 0.5 m. Continent-wise, only Australia, North and South America complied with the SRTM goal. At stations where all the X- and C-Band SRTM data were present, the RMSE of the outlier-filtered C-30 data was 11.7 m. However, the RMSE of outlier-included dataset where C- and X-Band data were present was ～233 m. The results suggest that the SRTM data must only be used after regional accuracy analysis and removal of outliers. If used raw, they may produce results that are statistically insignificant with RMSE in 100s of meters.     

A distributed water–heat coupled model for mountainous watershed of an inland river basin in Northwest China (II) using meteorological and hydrological data

A distributed water–heat coupled model (DWHC) is calibrated by using daily precipitation data from 26 hydrological and meteorological stations: daily averaged air temperature data from the 11 stations and daily pan evaporation data (E601) from the 15 stations in 2000. Six tests by using different spatial interpolation methods to calculate the above daily meteorological data in each 1 km × 1 km grid, are designed to simulate the mean daily runoff generated from the research Heihe mountainous watershed in 2000. Due to spatial sparseness and asymmetry of the hydrological and meteorological stations, the results of the six tests have little differences. The interpolation method in 3-D mode considering altitude is not better than those taking no account of altitude, nor are the model results when the daily meteorological data at the two stations far from the research watershed are complemented. At last, a nearest neighbor interpolation method in 2-D mode is used to calibrate the DWHC model, in which the revised Nash-Sutcliffe Efficiency NSE, balance error B, determinate coefficient R ², root mean square error RMSE and average absolute error MAE is about 0.61, 0.08%, 0.73, 25.0 and 15.8 m³s⁻¹, respectively. However, by using the daily data in 1999 to validate the model, the NSE, B, R ², RMSE and MAE are, respectively, 0.63, −2.98%, 0.77, 34.9 and 20.3 m³s⁻¹. The reason that the model result is not favorable is mainly because of the lack of detailed soil information, meteorological data and vegetation data; even worse, the basic equations for runoff generation processes are mainly derived from the research results in other regions and meanwhile, its flow concentration method should be improved too. The water balance of the research watershed in 2000 is also discussed in this paper. Though the runoff simulation results are not favorable, the estimated evapotranspiration and runoff components are in accordance with the usual knowledge qualitatively, parts of which meet with the field measurements. According to the model results, the runoff is mainly generated from the land surfaces and shallow soil layers in this cold mountainous watershed. The alpine meadow has evident water conservation function based on the model results, field investigation and field observation results. The DWHC model also reproduces the formation processes of the thick-layered ground ice to some extent, though it is suppositional due to lack of detailed soil, vegetation and meteorological information.     

Ferric/ferrous ratio in silicate melts: a new model for 1 atm data with special emphasis on the effects of melt composition

The effect of MgO and total FeO on ferric/ferrous ratio in model multicomponent silicate melts was investigated experimentally in the temperature range 1300–1500 °C at 1 atm total pressure in air. We demonstrate that the addition of these weak network modifier cations results in an increase of Fe³⁺/Fe²⁺ ratio in both mafic and silicic melts. Based on present and published experimental data, a new empirical equation is proposed to predict the ferric/ferrous ratio as a function of oxygen fugacity, temperature and melt composition. In contrast to previous equations, the compositional effect of melts on the Fe³⁺/Fe²⁺ ratio is not only modeled by the sum of the molar fraction of the individual oxide components. Additional interactions terms have also been incorporated. The main advantage of the proposed model is its applicability for a wide compositional range. However, its application to felsic melts (>?68 wt% SiO₂) is not recommended. Other advantages of this equation and differences when compared with previous models are discussed.     

Assessment of WRF numerical model forecasts using different lead time initializations during extreme precipitation events over Macaé city,Rio de Janeiro (Brazil)

Natural Hazards - The ability to forecast extreme precipitation events has become increasingly important over the last decades due to their significant impacts on society and properties. In this...     

Is Efate (Vanuatu, SW Pacific) a result of subaerial or submarine eruption? An alternative model for the 1 Ma Efate Pumice Formation

The Efate Pumice Formation (EPF) is a trachydacitic volcaniclastic succession widespread in the central part of Efate Island and also present on Hat and Lelepa islands to the north. The volcanic succession has been inferred to result from a major, entirely subaqueous explosive event north of Efate Island. The accumulated pumice-rich units were previously interpreted to be subaqueous pyroclastic density current deposits on the basis of their bedding, componentry and stratigraphic characteristics. Here we suggest an alternative eruptive scenario for this widespread succession. The major part of the EPF is distributed in central Efate, where pumiceous pyroclastic rock units several hundred meters thick are found within fault scarp cliffs elevated about 800 m above sea level. The basal 200 m of the pumiceous succession is composed of massive to weakly bedded pumiceous lapilli units, each 2-3 m thick. This succession is interbedded with wavy, undulatory and dune bedded pumiceous ash and fine lapilli units with characteristics of co-ignimbrite surges and ground surges. The presence of the surge beds implies that the intervening units comprise a subaerial ignimbrite-dominated succession. There are no sedimentary indicators in the basal units examined that are consistent with water-supported transportation and/or deposition. The subaerial ignimbrite sequence of the EPF is overlain by a shallow marine volcaniclastic Rentanbau Tuffs. The EPF is topped by reef limestone, which presumably preserved the underlying EPF from erosion. We here propose that the EPF was formed by a combination of initial subaerial ignimbrite-forming eruptions, followed by caldera subsidence. The upper volcaniclastic successions in our model represent intra-caldera pumiceous volcaniclastic deposits accumulated in a shallow marine environment in the resultant caldera. The present day elevated position of the succession is a result of a combination of possible caldera resurgence and ongoing arc-related uplift in the region.     

2D geological–geophysical model of the Timok Complex (Serbia,SE Europe): a new perspective from aeromagnetic and gravity data

The study reports new aeromagnetic and gravity data for the northern part of the Timok Magmatic Complex (TMC), East Serbia. The TMC is part of the Tethyan Eurasian metallogenic zone well known for hosting large copper and gold deposits. The complex formed by continuous volcanic activity 90–78 Ma ago, that developed in roughly three phases: Turonian andesites, Santonian–Campanian andesites/basaltic andesites (both mostly volcanic) and Campanian latites/monzonites (mostly shallow intrusive). The aeromagnetic measurements included acquiring total magnetic intensity data that were corrected for diurnal variations, leveling, microleveling, calculated normal field values, calculated anomaly values of total magnetic field intensity and reduction to the pole. The gravity measurements were carried out in an irregular grid with relative gravity values obtained using a Worden gravity meter. 2D modeling reveals that the subsurface extension of the Campanian Valja Str? pluton is ten times larger than it is indicated by its surface outcrops. This implies that the area south and southeast from the pluton can be interesting in terms of finding new porphyry systems. The model indicates that this intrusive body should not be considered as a deeply dissected pluton. This sheds new light onto its potential with respect to epithermal gold mineralization, as well. The model also suggests that there are larger non-exposed bodies of Santonian–Campanian volcanics and near-surface hydrothermally altered rocks than it is inferred from geological maps. The results of our study suggest that further interdisciplinary investigations in the TMC, in particular those integrating geophysics and geology, may have potential of advancing the existing exploration models.     

Detachment folding in a Lower Cambrian–Upper Permian karst reservoir: 3D model of the Yubei 3D area (eastern Markit Slope,Tarim Basin,Northwest China)

A three-dimensional (3D) structural modeling of the Lower Cambrian–Upper Permian Yubei 3D area was performed to understand its structural evolution. This model reproduces the present-day structure of the basin and comprises 11 horizons within Lower Cambrian to Upper Permian rocks. The analysis is based on 3D depth views and faults. The results image salt movements due to tectonics and/or burial. From these observations, this paper deduces that salt structures are correlated to the main faults and tectonic events. From the model analysis, we interpret the timing and geometry of Tarim Basin tectonics. The fault geometry can be resolved based on the strike of the fault, the morphology of hanging wall strata, and the stratigraphic distribution. Emphasis is placed on gypsum rock detachment, considering its movements during the Middle Caledonian event and decoupling effects during tectonic evolution. Moreover, we point to the structural control of the Paleozoic basement and the crustal architecture (Yubei 3D Zone) on the geometry of the Tarim Basin.