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Elaboration of a modern Earth system model (ESM) requires incorporation of ice sheet dynamics. Coupling of an ice sheet model (ICM) to an AOGCM is complicated by essential differences in spatial and temporal scales of cryospheric, atmospheric and oceanic components. To overcome this difficulty, we apply two different approaches for the incorporation of ice sheets into an ESM. Coupling of the Antarctic ice sheet model (AISM) to the AOGCM is accomplished via using procedures of resampling, interpolation and assigning to the AISM grid points annually averaged meanings of air surface temperature and precipitation fields generated by the AOGCM. Surface melting, which takes place mainly on the margins of the Antarctic peninsula and on ice shelves fringing the continent, is currently ignored. AISM returns anomalies of surface topography back to the AOGCM. To couple the Greenland ice sheet model (GrISM) to the AOGCM, we use a simple buffer energy- and water-balance model (EWBM-G) to account for orographically-driven precipitation and other sub-grid AOGCM-generated quantities. The output of the EWBM-G consists of surface mass balance and air surface temperature to force the GrISM, and freshwater run-off to force thermohaline circulation in the oceanic block of the AOGCM. Because of a rather complex coupling procedure of GrIS compared to AIS, the paper mostly focuses on Greenland.

For well over 300 years, the monsoon has been considered to be a gigantic land–sea breeze driven by the land–ocean contrast in surface temperature. In this paper, this hypothesis and its implications for the variability of the monsoon are discussed and it is shown that the observations of monsoon variability do not support this popular theory of the monsoon. An alternative hypothesis (whose origins can be traced to Blanford’s (1886) remarkably perceptive analysis) in which the basic system responsible for the Indian summer monsoon is considered to be the Intertropical Convergence Zone (ITCZ) or the equatorial trough, is then examined and shown to be consistent with the observations. The implications of considering the monsoon as a manifestation of the seasonal migration of the ITCZ for the variability of the Indian summer monsoon and for identification of the monsoonal regions of the world are briefly discussed.

The Bundelkhand massif, located in the northern part of the Indian shield, is a poly-deformed and poly-metamorphic terrain. This paper reports a new shear system developed throughout the massif in the form of N–S trending quartz veins that are sometimes quartzo-feldspathic and rarely granitic in composition. The veins are vertical and commonly occur in conjugate sets. This tectono-magmatic event appears to represent the youngest shear system of the massif as it cross-cuts all the earlier shear systems (E–W, NE–SE and NW–SE). Emplacement of this N–S vein system may have taken place due to extensional processes that developed some cracks along which siliceous magma was vertically emplaced. The complete absence of signature of the N–S event from the surrounding sedimentary cover of Vindhyan Supergroup, Bijawar and Gwalior Groups suggests that this shear system is pre-tectonic to the nearly E–W trending passive basins developed at the margins of the Bundelkhand craton. Further, several workers have considered the Bundelkhand massif as a part of the Aravalli craton. However, due to the absence of N–S, as well as the other (i.e., E–W, NW–SE and NW–SE), tectonic fabrics of the Bundelkhand massif in other cratons of the Peninsular India, and vice versa, makes the Bundelkhand block a separate and unique craton of its own and is not part of the Aravalli craton.

Urbanization has resulted in many critical issues like increase in pollution levels, sudden climatic changes and the rise of temperature in the urban area, that is the formation of Urban Heat Islands (UHI). As the density of population rises, most of the land areas are being converted into cities and cities grows very rapidly. Due to the UHI effect, the cities are becoming hotter day by day. In India, all the metropolitan cities are victims of UHI effect and the severity of heat formation, necessitates research in this area. The present paper evaluates the trends of UHI studies in Indian cities and its out reach till 2018. Heat Island classification, methods of studying UHI in India and their limitation are discussed. Eventually a comparison of new trends of UHI studies in the world and where India lacks its growth in UHI research are included in this paper. One of the findings is that numerical modelling studies are very limited in India in this field and more focus in this area is required.

Assessing sustainability of coastal groundwater is significant for groundwater management as coastal groundwater is vulnerable to over-exploitation and contamination. To address the issues of serious groundwater level drawdown and potential seawater intrusion risk of a multi-layered coastal aquifer system in Zhanjiang, China, this paper presents a numerical modelling study to research groundwater sustainability of this aquifer system. The transient modelling results show that the groundwater budget was negative ($$-3826\times 10^{4}$$ -3826×104 to $$-4502\times 10^{4 }\,\hbox {m}^{3}/\hbox {a}$$ -4502×104m3/a ) during the years 2008–2011, revealing that this aquifer system was over-exploited. Meanwhile, the groundwater sustainability was assessed by evaluating the negative hydraulic pressure area (NHPA) of the unconfined aquifer and the groundwater level dynamic and flow velocity of the offshore boundaries of the confined aquifers. The results demonstrate that the Nansan Island is most influenced by NHPA and that the local groundwater should not be exploited. The results also suggest that, with the current groundwater exploitation scheme, the sustainable yield should be $$1.784\times 10^{8}\, \hbox {m}^{3}/\hbox {a}$$ 1.784×108m3/a (i.e., decreased by 20% from the current exploitation amount). To satisfy public water demands, the 20% decrease of the exploitation amount can be offset by the groundwater sourced from the Taiping groundwater resource field. These results provide valuable guidance for groundwater management of Zhanjiang.

The effects of climate change and overexploitation are being strongly perceived in the studied area and the springs discharge is obviously affected. In this paper, Ras El Ain spring discharge and precipitation were analyzed by normalized methods on an yearly timescale. The deficit of Ras El Ain spring discharge due to overexploitation factors and drought effects was estimated. Cumulative drought analyses were carried out using SPI10 and SQI10. Finally, the decreasing trends of the spring discharge due to the deficiency in rainfall were analyzed. The main results reveal that the annual mean deficit of Ras El Ain spring discharge due to overpumping was between 32 and 45%, whereas, annual mean deficit related to drought was between 22 and 35% on average, during the last 30 years (post-1984). The moving averages of SPI and SQI delineate very well the drought periods during last three decades. The cumulative droughts using SPI10 and SQI10 reveal that wet period (pre-1984) with positive values was characterized by high precipitation and spring discharge. Overexploitation period (1984–1989) is distinguished by decreasing SQI10 values whereas, SPI10 is almost stable. The response of the karst system to the precipitation signal has been changed, during the drought period (1990–2000), and the spring behaviour has been modified due to the first overexploitation period. Finally, overexploitation period (2001–2008) is related to the second phase of groundwater intensive pumping for irrigation purposes. Consequently, this period is completely catastrophic causing the drying up of the spring. The decreasing trends analyzed using DPI and DQI showed annual decreasing rates relative to the mean values of −0.268% and −0.105%, respectively. Thus, the results of theoretical model reveal that precipitation will decrease by about $$\hbox {DPI} = -20.7$$ DPI=-20.7 % and the discharge will decline by about −9.2% by 2050. Consequently, the declining discharge due to climatic variation under natural conditions as pre-1984 was about 10%. Whereas, the catastrophic drying up of the spring was probably the consequence of the anthropogenic effects. Accordingly, it requires the development of sustainable water resources management program to reduce long-term drought risks, restore the groundwater reservoir and minimize the overexploitation effects on spring discharge.

Dislocation modelling of an earthquake fault is of great importance due to the fact that ground surface response may be predicted by the model. However, geological features of a fault cannot be measured exactly, and therefore these features and data involve uncertainties. This paper presents a Monte Carlo based random model of faults with finite element method incorporating split node technique to impose the effects of discontinuities. Length and orientation of the fault are selected as random parameters in the domain model, and hence geometrical uncertainties are encountered. Mean and standard deviation values, as well as probability density function of ground surface responses due to the dislocation are computed. Based on analytical and numerical calculation of dislocation, two approaches of Monte Carlo simulations are proposed. Various comparisons are examined to illustrate the capability of both methods for random simulation of faults.

The Gafsa and Chotts intracratonic basins in south-central Tunisia are transitional zones between the Atlasic domain to the north and the Saharan platform to the south. The principal aim of this paper is to unravel the geodynamic evolution of these basins following an integrated approach including seismic, well log and gravity data. These data are used to highlight the tectonic control on the deposition of Jurassic and Lower Cretaceous series and to discuss the role of the main faults that controlled the basin architecture and Cretaceous–Tertiary inversion. The horizontal gravity gradient map of the study area highlights the pattern of discontinuities within the two basins and reveals the presence of deep E–W basement faults. Primary attention is given to the role played by the E–W faults system and that of the NW–SE Gafsa fault which was previously considered active since the Jurassic. Facies and thickness analyses based on new seismic interpretation and well data suggest that the E–W-oriented faults controlled the subsidence distribution especially during the Jurassic. The NW–SE faults seem to be key structures that controlled the basins paleogeography during Late Cretaceous–Cenozoic time. The upper Triassic evaporite bodies, which locally outline the main NW–SE Gafsa fault, are regarded as intrusive salt bodies rather than early diapiric extrusions as previously interpreted since they are rare and occurred only along main strike-slip faults. In addition, seismic lines show that Triassic rocks are deep and do not exhibit true diapiric features.

Amount of available net energy and its partitioning into sensible, latent and soil heat fluxes over an agricultural landscape are critical to improve estimation of evapotranspiration and modelling parse (ecosystem modelling, hydrological and meteorological modelling). Scintillometry is a peculiar and robust methodology to provide structure parameter of refractive index and energy balance. Scintillometer has proven for assessment of sensible and latent heat flux, which is based on the principle of Monin–Obukhov similarity theory. Scintillometer has been installed in the agricultural experimental farm of ICAR-Indian Agricultural Research Institute, New Delhi, with a spatial covering path length of 990 m of irrigated and cultivable agricultural landscape. This paper discusses the patterns of energy flux as diurnal and seasonal basis at scintillometer path which was mainly covered by maize in Kharif and wheat in Rabi season during a crop growing seasons of 2014–2015. The biophysical parameters (leaf area, soil moisture, crop height) were recorded at a temporal resolution of fortnight basis along the path length at usual sampling distance. The Bowen ratio value for both Kharif and Rabi season was 0.76 and 0.88, respectively by scintillometer. Leaf area index had a significantly positive correlation with latent heat flux ($$R^{2} =0.80$$ R2=0.80 ) while a significantly negative correlation with sensible heat flux ($$R^{2}{=}-0.79$$ R2=-0.79 ). Soil moisture had a significant negative correlation with sensible heat flux ($$R^{2}{=}-0.68$$ R2=-0.68 ). The average evapotranspiration from crop land was $$1.58 ~\hbox {mm d}^{-1}$$ 1.58mmd-1 and total evapotranspiration was 543 mm over the 12 months study period. This study defines that large aperture scintillometer is robust instrument which can evaluate energy flux over a large area with a long term series time domain. Moreover, further studied should be conducted to use in crop simulation modelling, developing of new model with calibration and validation of remote sensing energy balance algorithm, etc.

This paper has developed a general Ts-NDVI triangle space with vegetation index time-series data from AVHRR and MODIS to monitor soil moisture in the Mongolian Plateau during 1981–2012, and studied the spatio-temporal variations of drought based on the temperature vegetation dryness index (TVDI). The results indicated that (1) the developed general Ts-NDVI space extracted from the AVHRR and MODIS remote sensing data would be an effective method to monitor regional drought, moreover, it would be more meaningful if the single time Ts-NDVI space showed an unstable condition; (2) the inverted TVDI was expected to reflect the water deficit in the study area. It was found to be in close negative agreement with precipitation and 10 cm soil moisture; (3) in the Mongolian Plateau, TVDI presented a zonal distribution with changes in land use/land cover types, vegetation cover and latitude. The soil moisture is low in bare land, construction land and grassland. During 1981–2012, drought was widely spread throughout the plateau, and aridification was obvious in the study period. Vegetation degradation, overgrazing, and climate warming could be considered as the main reasons.

Given the significant worldwide human and economic losses caused due to floods annually, reducing the negative consequences of these hazards is a major concern in development strategies at different spatial scales. A basic step in flood risk management is identifying areas susceptible to flood occurrences. This paper proposes a methodology allowing the identification of areas with high potential of accelerated surface run-off and consequently, of flash-flood occurrences. The methodology involves assessment and mapping in GIS environment of flash flood potential index (FFPI), by integrating two statistical methods: frequency ratio and weights-of-evidence. The methodology was applied for Bâsca Chiojdului River catchment (340 $$\hbox {km}^{2}$$ km2 ), located in the Carpathians Curvature region (Romania). Firstly, the areas with torrential phenomena were identified and the main factors controlling the surface run-off were selected (in this study nine geographical factors were considered). Based on the features of the considered factors, many classes were set for each of them. In the next step, the weights of each class/category of the considered factors were determined, by identifying their spatial relationships with the presence or absence of torrential phenomena. Finally, the weights for each class/category of geographical factors were summarized in GIS, resulting the FFPI values for each of the two statistical methods. These values were divided into five classes of intensity and were mapped. The final results were used to estimate the flash-flood potential and also to identify the most susceptible areas to this phenomenon. Thus, the high and very high values of FFPI characterize more than one-third of the study catchment. The result validation was performed by (i) quantifying the rate of the number of pixels corresponding to the torrential phenomena considered for the study (training area) and for the results’ testing (validating area) and (ii) plotting the ROC (receiver operating characteristics) curve.

Reservoir characterization of sand-shale sequences has always challenged geoscientists due to the presence of anisotropy in the form of shale lenses or shale layers. Water saturation and volume of shale are among the fundamental reservoir properties of interest for sand-shale intervals, and relate to the amount of fluid content and accumulating potentials of such media. This paper suggests an integrated workflow using synthetic data for the characterization of shaley-sand media based on anisotropic rock physics (T-matrix approximation) and seismic reflectivity modelling. A Bayesian inversion scheme for estimating reservoir parameters from amplitude vs.offset (AVO) data was used to obtain the information about uncertainties as well as their most likely values. The results from our workflow give reliable estimates of water saturation from AVO data at small uncertainties, provided background sand porosity values and isotropic overburden properties are known. For volume of shale, the proposed workflow provides reasonable estimates even when larger uncertainties are present in AVO data.

Present paper uses powerful technique of interval neural network (INN) to simulate and estimate structural response of multi-storey shear buildings subject to earthquake motion. The INN is first trained for a real earthquake data, viz., the ground acceleration as input and the numerically generated responses of different floors of multi-storey buildings as output. Till date, no model exists to handle positive and negative data in the INN. As such here, the bipolar data in [ −1, 1] are converted first to unipolar form, i.e., to [0, 1] by means of a novel transformation for the first time to handle the above training patterns in normalized form. Once the training is done, again the unipolar data are converted back to its bipolar form by using the inverse transformation. The trained INN architecture is then used to simulate and test the structural response of different floors for various intensity earthquake data and it is found that the predicted responses given by INN model are good for practical purposes.

A number of models have been established to simulate the behaviour of solute transport due to chemical pollution, both in croplands and groundwater systems. An approximate polynomial solution to convection–dispersion equation (CDE) based on boundary layer theory has been verified for the use to describe solute transport in semi-infinite systems such as soil column. However, previous studies have only proposed low order polynomial solutions such as parabolic and cubic polynomials. This paper presents a general polynomial boundary layer solution to CDE. Comparison with exact solution suggests the prediction accuracy of the boundary layer solution varies with the order of polynomial expression and soil transport parameters. The results show that prediction accuracy increases with increasing order up to parabolic or cubic polynomial function and with no distinct relationship between accuracy and order for higher order polynomials ( n⩾3 $n\geqslant 3$). Comparison of two critical solute transport parameters (i.e., dispersion coefficient and retardation factor), estimated by the boundary layer solution and obtained by CXTFIT curve-fitting, shows a good agreement. The study shows that the general solution can determine the appropriate orders of polynomials for approximate CDE solutions that best describe solute concentration profiles and optimal solute transport parameters. Furthermore, the general polynomial solution to CDE provides a simple approach to solute transport problems, a criterion for choosing the right orders of polynomials for soils with different transport parameters. It is also a potential approach for estimating solute transport parameters of soils in the field.

In this paper, numerical simulations of regional-scale groundwater flow of North Bengal Plain have been carried out with special emphasis on the arsenic (As)-rich alluvium filled gap between the Rajmahal hills on the west and the Garo hills on the east. The proposed concern of this modelling arose from development that has led to large water table declines in the urban area of English Bazar block, Malda district, West Bengal and possible transport of As in the near future from the adjacent As-polluted aquifer. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternary alluvial sediments. Modelling indicates that current pumping has significantly changed the groundwater flowpaths from pre-development condition. At the present pumping rate, the pumping wells of the urban area may remain uncontaminated till the next 25 yrs, considering only pure advection of water but some water from the As-polluted zone may enter wells by 50 yrs. But geochemical and other processes such as adsorption, precipitation, redox reaction and microbial activity may significantly retard the predicted rate by advective transport. In the rural areas, majority of the water pumped from the aquifer is for irrigation, which is continuously re-applied on the surface. The near-vertical nature of the flowpaths indicates that, where As is present or released at shallow depths, it will continue to occur in pumping wells. Modelling also indicates that placing all the pumping wells at depths below 100 m may not provide As-free water permanently.

In this paper, analytical methods, artificial neural network (ANN) and multivariate adaptive regression splines (MARS) techniques were utilised to estimate the discharge capacity of compound open channels (COC). To this end, related datasets were collected from literature. The results showed that the divided channel method with a coefficient of determination (R2) value of 0.76 and root mean square error (RMSE) value of 0.162 has the best performance, among the various analytical methods tested. The performance of applied soft computing models with R2=0.97 and RMSE = 0.03 was found to be more accurate than analytical approaches. Comparison of MARS with the ANN model, in terms of developed discrepancy ratio (DDR) index, showed that the accuracy of MARS model was better than that of MLP model. Reviewing the structure of the derived MARS model showed that the longitudinal slope of the channel (S), relative flow depth (Hr) and relative area (Ar) have a high impact on modelling and forecasting the discharge capacity of COCs.

An approach for extracting angle-domain common-image gathers (ADCIGs) from anisotropic Gaussian beam prestack depth migration (GB-PSDM) is presented in this paper. The propagation angle is calculated in the process of migration using the real-value traveltime information of Gaussian beam. Based on the above, we further investigate the effects of anisotropy on GB-PSDM, where the corresponding ADCIGs are extracted to assess the quality of migration images. The test results of the VTI syncline model and the TTI thrust sheet model show that anisotropic parameters ε, δ, and tilt angle 𝜃, have a great influence on the accuracy of the migrated image in anisotropic media, and ignoring any one of them will cause obvious imaging errors. The anisotropic GB-PSDM with the true anisotropic parameters can obtain more accurate seismic images of subsurface structures in anisotropic media.

This paper aims to discuss the depositional settings and provenances for the Jurassic in Jiyuan basin, North China, based on the rare earth element (REE) and trace element features of 16 Jurassic argillaceous rock samples from the Anyao, Yangshuzhuang and Ma’ao Formations, respectively. Generally, geochemical analysis results show that chondrite-normalised REE distribution patterns of all the three formations are characterised by light-REE (LREE) enrichment, moderately negative Eu anomalies, slightly negative Ce anomalies, and strong fractionation between LREE and heavy-REE (HREE). Trace element proxies V/(V + Ni), Ce anomindex, Ce/La, Sr/Ba, and Sr/Cu indicate a weak oxidation–reduction environment, progressively decreasing reducibility and water depth from the bottom up during Jurassic in Jiyuan basin. Palaeoclimate varied from humid in the Early Jurassic to arid in the Middle Jurassic, corresponding with the variations of palaeoredox and palaeosalinity. The provenances of Jurassic rocks in Jiyuan basin are mainly from felsic sources related to active continental margin and continental island arc. The Early–Middle Jurassic (Anyao and Yangshuzhuang Formations) provenances are mainly derived from North Qinling and partially from the eroded recycled felsic sedimentary covers of Taihang Mountain. In the late stage of Middle Jurassic (Ma’ao Formation), Taihang Mountain has been the primary source to Jiyuan basin. We conclude that the Jurassic rocks of Jiyuan basin reveal the progressive uplift and denudation processes of the Taihang Mountain.

Abstract: The heavy mineral assemblage (HMA) of sandstones belonging to Mesoproterozoic Kaimur Group in the eastern Son valley, Central India, was investigated. The present communication is aimed at assessing mineralogical maturity, quantifying the contribution of heavy fraction to the bulk rock and its REE budget, sediment recycling and provenance. The transparent heavies record a relative decreasing trend upwards from 63 to 36.4% and on the contrary, opaque heavies show gradual increasing trend upwards from 36.4 to 65.4%. Tourmaline in the transparent heavy fraction reveals an overall decreasing trend of 59–22.8%. Whereas, zircon registers an increasing trend of 3.3–9.5% stratigraphically upwards. The contribution of opaque detrital clasts of ferruginous material composed of hematite and magnetite increases in the Upper Kaimur Sandstone. Tourmaline and zircon grains are characterised by etched, pitted and grooved surfaces. Zircon is also present as tiny inclusion within tourmaline and zircon itself. Heavy fraction of Upper Kaimur sandstone from the lower stratigraphic horizon exhibit lower ∑REE as compared to higher levels. The heavy fraction exhibit LREE/HREE < 1 as compared to bulk rock which has 8–10 times higher ratio. Heavy fraction exhibits enrichment in HREE and [Gd/Yb]N= 0.36–0.43, stratigraphically upwards, which is consistent with increasing Zr values suggesting zircon to be the major contributor to the REE budget of Upper Kaimur Sandstones. The percentage contribution of the zircon to the REE budget of bulk rock could have been ~50–60%. ZTR index (99–100) reveals mineralogically mature nature of Kaimur sandstones. Dominance of zircon amongst the heavies and Th/Sc vs.Zr/Sc plot shows the effect of zircon addition and sediment recycling. The plausible explanation for dominance of opaque minerals in HMA in the Upper Kaimur reflects their contribution from Paleoproterozoic metasedimentary rocks of Mahakoshal Group. HMA of Kaimur sandstones suggests derivation from granitic source. Nb/Yb vs.U/Yb diagram indicates that zircon was derived from magmatic arc source, which is in conformity with inference that Bundelkhand Granite Complex and Chhotanagpur Granite complex dominantly contributed to the Lower and Upper Kaimur Groups, respectively. Research highlights:

The paper deals with the study of heavy mineral assemblage of the Kaimur Group sandstones, Vindhyan Supergroup, Son Valley, Central India. Provenance, sorting and recycling of the sediments were inferred. The ferruginous clasts found in the Dhandraul Quartzite/Sandstone also have been studied to understand their mineralogy and texture.

Tourmaline and zircon dominate the Lower and Upper Kaimur Sandstones, respectively. The provenance of the Lower Kaimur sandstones is Bundelkhand granite, and Upper Kaimur sandstone is Chhotanagpur Gneissic Complex. The dominance of zircon in HMA and Th/Sc vs. Zr/Sc plot shows the significant effect of zircon addition and sediment recycling. The occurrence of ferruginous detrital clasts in Upper Kaimur sandstones can be attributed to increasing detrital input from adjoining Mahakoshal Group that has the presence of BIFs/BHQ/BHJ in the Agori Formation.

The heavy fractions from sandstones of Mangesar Formation and Dhandraul Quartzite from different horizons exhibit an increase in Zr and HREE stratigraphically upwards. This suggests remarkable enrichment of HREE, low LREE/HREE, [La/Yb]N<1 and [Gd/Yb]N<1. HREE enrichment is proportional to the Zr concentration signifying the dominant role of zircon amongst the heavies in managing the ΣREE budget of the bulk rock. The percentage contribution of the zircon is calculated to be ~50–60%.

Coalbed Methane (CBM) reservoirs demonstrate sensitivity to in-situstress conditions. The depletion of reservoir pressure due to production leads to changing stress conditions within the reservoir. The matrix shrinkage phenomenon due to the coal matrix gas desorption results in altering the pore volume of the cleat network. Consequently, the porosity and permeability of the coal cleat system change as pressure depletes. This phenomenon contradicts the assumption made in the derivation of the diffusivity equation. The inherent assumption of reservoir properties produces inaccurate results for CBM reservoirs during conventional pressure transient analysis under the stress-driven permeability effects. This study deals with the issues related to pressure-dependent diffusivity in dry CBM reservoirs. In this paper, the authors attempt to present a new equation that incorporates pressure-dependent cleat porosity and permeability in the transient state flow equation for dry CBM reservoirs. The concept of stress-dependent pseudo pressure (SDPP) and pseudo-time has been leveraged to derive a new solution to the diffusivity equation under transient flow conditions. The outcome of this study finds its application in accurately estimating the cleat permeability and skin in a dry CBM well that flows with reservoir conditions of pressure-dependent permeability.

The purpose of this paper is to analyse the trends and variability in extreme temperature indices. We examined climatological distribution of heat and cold waves of two important agro-climatic zones (South Bihar Alluvial Zone-IIIA and B), which is part of the middle Indo-Gangetic Basin and comprising 17 densely populated (1108 persons/km 2) districts of Bihar state. We used series of daily maximum and minimum temperature data from 1969 to 2013 of seven stations to calculate temperature indices, from which the trend, occurrence, duration and severity of heat and cold waves were estimated. Results revealed that, in a period of 45 years, zone-IIIA and B has experienced 251/182 and 337/140 average number of heat and cold events, respectively. Although the zone-IIIA on average is experiencing ≥8 heat and cold wave days per season, both these high frequency temperature extremes are decreasing at the rate 0.15 and 0.17 per year, respectively, with significance at 95% confidence level. Zone-IIIB on average is experiencing ≤5 heat and cold days per season, but heat waves have been found increasing at the rate 0.11 per year, whereas, a non-significant decreasing rate of 0.04/year was observed in cold waves. The study also inferred that heat waves of the month of May in zone-IIIA and of June in zone-IIIB are more frequent, hotter and longer than other months of hot weather period under study, whereas, the cold waves of month January are more frequent and longer, in both zones.

The present paper deals with pre-seismic soil radon-222 recorded at two different locations 200 m apart, at Jadavpur University main campus, Kolkata, India. Solid state nuclear track detector method is used for detection of the radioactive radon gas. Two simultaneous 4-month long time series data have been analysed. Anomalous fluctuations in the radon datasets have been observed prior to recent earthquakes in Nepal and eastern India during the monitoring period, mainly, the massive 25th April 7.8 M Nepal earthquake. The simultaneous measurements assist in identifying seismogenic radon precursor efficiently.

A coastline is a random fractal object in a geographical system whose length is uncertain. To determine the coastline length of a country or a region, the scaling region and fractal dimension of the coastline is first calculated, and then, the length of the coastline is measured using the scale at the lower limit or near the limit of the scaling region. For this study, the scaling region of the continental coastline of China is determined. The box-counting dimension was calculated with ArcGIS software using 33 scales and a map scale of 1:500,000, and the divider dimension calculated by a C language program. Moreover, the reliability of the Chinese coastline length value, which is widely used currently, is discussed in this paper. The results show that the scaling region of the continental coastline of China is from 0.1 to 400 km. In the scaling region, the box-counting dimension and the divider dimension of the coastline are 1.2004 and 1.0929, respectively. According to fractal theory, the divider dimension more accurately represents the irregularity of a coastline. The length of the continental coastline of China is approximately 21,900 km when the measurement scale is 0.1 km; however, the length is 18,214 km when the scale is 0.25 km, and this value approaches the continental length of China (18,400 km) in popular use today. Although the coastline length is shorter than 21,900 km, the length is acceptable because the measurement scale (0.25 km) is close to the lower limit of the scaling region.

Through a multidisciplinary approach based on geological mapping, field observations, paleostress analysis and some seismic data, this paper is aimed to better constrain the Upper Cretaceous–Quaternary structural evolution of the NW–SE trending el Kef and Sers grabens (north-central Tunisia), and to explain the coexistence of extensional and compressional structures in this region. We suggest that grabens are mechanically linked by the Boulifa E–W trending dextral shear zone. Results reveal a major NE–SW extensional phase during the Upper Cretaceous–Paleocene time, as proved by NW–SE and E–W trending synsedimentary normal faults. The examination of the geological cross-section along the salt structures (e.g., Jebel Debadib) enables us to notice that several zones of the el Kef area have been marked by bald areas. These highs have been formed after Triassic vertical movement and they were responsible for the absence of some series of the Upper Cretaceous and Paleocene. On the other hand, results document a NW–SE trending compressional phase, during early Eocene, that affected the study area. Extension with main NE–SW direction took place during the early-middle Miocene, giving raise the el Kef and Sers grabens opening. However, from late Miocene until Quaternary, the study area was affected by two major contractional events with NW–SE to NNW–SSE directed shortening. The first one gave rise to the reactivation of the pre-existing normal faults and NE–SW trending folds and thrust structures. The compression event still remains active during the Quaternary (post-Villafranchian). During both Neogene shortening events, the paleostress analysis reveals a NE–SW trending extension in regional compressional phase. We interpret this extensional tectonic event as a local effect due to the perturbation of the principal stress axis, guided by the continental collision between the African and Eurasian plates.

In this paper, we discuss the necessity of mapping of characterisation of unapproachable underground mine workings by electrical resistivity tomography (ERT). Initially, numerical forward modelling is conducted for considering the possibilities of water fill and air fill void in old workings using Wenner–Schlumberger (WS), dipole–dipole (DD) and inversion of joint of both arrays (WS+DD). Considerable accuracy of cavities dimension, depth and extensions could be recovered from data inversion of joint of both arrays (WS+DD). In field, 2D ERT survey was conducted along three parallel profiles using said configurations over Jharia coalfield, India. Inversion of joint of both arrays was introduced during data analysis for propensities of better demarcation of underground mine workings characterisations under complex geological formations. Furthers, pseudo-3D model was also done by merging 2D ERT parallel profile data for improved visualisation of 3D resistivity distributions of surveyed area. High resistivity contrast in 2D ERT model and 3D volumetric iso-resistivity model provided comfortable guidance in the investigation of possible continuity of barrier between caved panels of XVIA seam. Moderately low resistivity indicated anticipation of XVII seam working filled with water and also validated through the existing mine plan. Thus, interpretation of 3D data eventually helped in convincing outcomes.

The present paper attempts to quantify the amount of soil loss occurring in the Mayurakshi River basin of eastern India with the help of the empirical Revised Universal Soil Equation (RUSLE) Model. The areas of high erosion were identified and their spatial and temporal patterns and trends were monitored for the years 2008 and 2018. It was observed that the average soil loss increased by about 6% from 2008 to 2018. Among a variety of causal factors, the Shannon’s Entropy Index used in this study has identified the slope length and steepness factor (LS factor) as the most significant causal factor of erosion in the studied river basin. One of the novel approaches used in this study is the application of landscape ecological metrics in the domain of temporal erosion monitoring. An important conclusion drawn from the analysis is that the patches of high and moderate erosion are increasing significantly in terms of areal extent, whereas the extent of the patches of low erosion is decreasing with time. Therefore, appropriate management strategies prioritised on the high and moderate erosion patches are the need of the hour.

Abstract: The region between the southern tip of the Indian subcontinent and the equator links the Arabian Sea and the Bay of Bengal. A significant exchange of mass, heat and salt occurs in the region via two major current systems: the monsoon current (dominant annual cycle) and the equatorial current (dominant semi-annual cycle). This paper presents observations from deep-sea mooring programmes and describes the rationale for maintaining a mooring array along 77.4${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}E to monitor both current systems. Analysis shows that the semi-annual to annual cycle transition occurs at 2–2.5${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}N, with the winter monsoon current peaking at 5${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}N, the summer monsoon current at 3–6${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}N, and the equatorial current at 0–1${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}N. Research highlights:

Ocean current observations are shown in the monsoon and equatorial currents regime at 77.4${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}E.

The transition between monsoon and equatorial current occurs at 2-2.5${}^{\circ }$\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ $$\end{document}N.

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Minor expansion of existing mooring programmes to monitor two major current systems in the North Indian Ocean is proposed.

Central Tibet constitutes part of the central part of the Qinghai–Tibetan Plateau, which is one of the highest seismically active areas in China. This paper discusses the regularity of seismic activity in this area. Based on a stratified viscoelastic earth model, we calculated the Coulomb stress changes imparted from four strong earthquakes (M≥ 6.3) along the Bengco–southeastern piedmont of the Nyainqentanglha mountain fault zone in this region. The result shows that the study area may be entering a new active period from 2020. There was a trigger between the strong earthquakes (M≥ 6.3) on the Bengco fault zone. The post-seismic viscous relaxation effect of a strong earthquake had a significant impact on subsequent earthquakes (M≥ 6.3). In the next 100 years, the Coulomb stress loading is more than 1.0 MPa in the northwest section of the Bengco fault and the central part of Nimu segment of the southeastern piedmont of the Nyainqentanglha mountain fault. Thence, strong earthquakes may occur along these fault segments. The maximum magnitude of the earthquake could be M6.7 in the next 100 years.

The magmatism in Kachchh is associated with the northwestern Deccan Continental Flood Basalt Province (CFB) (~65–68 Ma). They form the base of the local Deccan stratigraphy, and their volcanological context is poorly understood. Apart from the flow, there are isolated hills of volcanic rocks, which have stood against the erosional processes that occurred in the basin. This paper provides an overview of features indicative of the interaction between water and lava and/or magma in Kachchh and their suitability as analogue for Mars. We have surveyed <22 craters/cones within the basin for their relevancy as planetary analogue. Evaluated during field investigations and satellite imagery for structures, physiography, and geologic setting concerning climate change from its evolution. The weathering profile and altered aqueous minerals are also proven analogues from the basin. We propose the Dhinodhar, Varar, and other basaltic vents as an analogue for the Ceraunius, Hecates Tholus, and Volcanic Rootless Constructs (VRCs) of Mars.

In this paper, the performance of a multi-satellite hybrid satellite-terrestrial relay network (HSTRN) is investigated, where a relay is adopted using either amplify-and-forward (AF) or decode-and-forward (DF) protocol to assist the transmission, considering Shadowed-Rician fading for satellites links and Rayleigh fading for terrestrial link. To evaluate the performance of the considered network, the accurate analytical expression for the outage probability (OP) is derived. In order to get further insights into the achievable diversity order of the system, the asymptotic behaviour of OP expression at high signal-to-noise ratio (SNR) regime is deduced. The throughput of the system is also discussed to evaluate the network performance. Finally, the theoretical results are validated through comparison with simulations and show: (1) The performance of the considered network gets better with the increase of the satellite number and with the decreasing severity of the channel fading scenario. (2) The performance of the DF relaying system is better than AF at low SNR region, while they will get increasingly consistent at high SNR region.

The Central Water Commission (CWC) revised its estimates of water resources availability (WRA) for river basins of India in June 2019 (CWC19). Despite more than six years of modelling effort, several major drawbacks remain – the model needs extensive inputs on water management and seasonal crop growth; model calibration is cumbersome and not very effective; and, it cannot be easily extended to other years or ungauged basins. This paper proposes a conceptually equivalent, but simpler, alternative to estimate WRAusing evapotranspiration (ET) products based on remote sensing or land surface models (ETRS). In this approach, WRAis formulated in terms of ETand necessary assumptions are made to account for ETfrom irrigated areas. The proposed alternative does not involve any modelling, does not require any inputs on water management or crop growth, and is applicable even in ungauged basins. The analysis presented here has two main parts. In the first part, since ETRSproducts are prone to systematic biases they are evaluated for their validity against basin-scale proxy observations of ET. In the second part, the validated ETRSproducts are used to estimate WRAusing the proposed approach. Over Godavari and Krishna river basins of peninsular India, and also 15 sub-basins within these two basins, five state-of-the-art ETRSproducts (ERA5-Land, GLEAM, NTSG/MOD16, NTSG/PLSH and FEWS/SSEBop) are evaluated. At a basin-scale two of these products, ERA5 and SSEBop, are found to have limited bias and reasonably captured annual basin-scale ET. Using these two products, WRAis estimated for the two basins and their 15 sub-basins. Resulting WRAestimates are found to be similar to, and highly consistent with, those from CWC19. Potential causes of discrepancies in WRAbetween CWC19 and this study are discussed, drawbacks of this approach and potential improvements, and next steps in expanding this work to other river basins of India are also discussed.

Numerical oil spill trajectory modelling aims at predicting and forecasting the movement of the oil spill. This paper discusses trajectory oil spill modelling for the hypothetical oil spills in the Bay of Bengal, off the Odisha coast. The models have been simulated in different locations of Odisha offshore for various weather conditions. The result showed that the northeast monsoon drives the slick faster than the southwest monsoon. A spill from 85 to 110 km away from the beach reached the coastline with higher speed in the cyclonic period. At the same time, the spill location at 70 km away from the coast could not reach the coast; this implies direction and speed of the wind and current play a critical role in spill movement. The fate budget of spill oil shows about 36% of evaporation happened in each case which shows that the period of spill and distance are not impacting the fate of oil. The direction of oil slick movement and speed are essential to understand the beaching of the oil pollutant at the shore. The study concluded that wind and ocean currents significantly influence oil spill movement.

This paper conducts a petrogeochemical analysis of the Lower Cretaceous Laiyang Group’s sandstones, compares the results with the Neoproterozoic and Mesozoic intrusive rocks in the southern Sulu Orogen (also called the Jiaonan Orogen), and performs an LA-ICP-MS zircon geochronology analysis of the granitic gneisses in the conglomerates of the Laiyang Group and the intrusive rocks in the Jiaonan Orogen. The results show that the major element proportions of the Longwangzhuang Formation (LWZ Fm) and Qugezhuang Formation (QGZ Fm) of the Laiyang Group in the Zhucheng Basin are similar. The values of various indices for the LWZ Fm are similar to the average sandstone content of active continental margins, whereas, the values for the QGZ Fm are similar to those of continental island arcs. The comparison shows that the REE characteristics of the LWZ Fm and QGZ Fm of Laiyang Group are similar to those of the Neoproterozoic granitic gneisses in the Jiaonan Orogen but obviously different from those of the Early Cretaceous intrusive rocks. A tectonic setting discrimination diagram reveals that the provenance of the Laiyang Group includes features of active continental margins and continental island arcs. A number of indicators, e.g., the sandstone type, the Chemical Index of Alteration, the Chemical Index of Weathering, the Plagioclase Index of Alteration and the Index of Chemical Constituent Variation, indicated that the sandstones did not undergo intense weathering and were deposited near the source area. The zircon ages of the granitic gneiss material in the conglomerates at the base of the Laiyang Group are 790 ± 8.4 Ma, close to the ages of the Neoproterozoic granitic gneiss in the Jiaonan Orogen (739–819 Ma), and very different from the ages of the Early Cretaceous intrusive rocks. Combining with paleocurrent directions, geochemical character, the Neoproterozoic granitic gneisses in the Jiaonan Orogen may represent the primary provenance of the Laiyang Group in the Zhucheng Basin. During the depositional period of the Laiyang Group, the source rocks did not experience intense weathering, which indicated the Jiaonan Orogen experienced rapid uplift during this time, and coincided with the high exhumed rate of 2.0 km Ma −1from before ca. 128 to 123 Ma in Jiaonan Orogen. The rapid subsidence during the formation of the Laiyang Group in the Zhucheng Basin and the rapid uplift of the Jiaonan Orogen are the result of a single regional extensional event associated with the lithospheric thinning and destruction of North China and peripheral cratons.

This paper presents results of a study of long term trends in the characteristics of the within-season temporal profile of southwest monsoon rainfall over western India during the last five decades in relation to global warming induced regional climate change. In contrast to recent climate change analyses and projections, no significant long-term trends have been observed in this study. Slow decadal scale variations observed are analysed in relation to Pacific Decadal Oscillations (PDO). Daily variations in rainfall anomaly show opposite characteristics during negative and positive phases of PDO. The above-normal rainfall (>25%) is found during the starting phase of monsoon in negative PDO. Over the last decade, i.e., during 2000–2007, the seasonal rainfall amount, as well as seasonal span of southwest monsoon over western India is indicative of a gradual increase.

The Abor volcanics of the continental flood basalt affinity are extensively exposed in different parts of the Siang valley. These are associated with Yinkiong Group of rocks of Paleocene–Eocene age and represent syn-sedimentary volcanism in a rift setting. Subsequent folding and thrusting of the Siyom and Rikor sequences above the Yinkiong Group of rocks represent changes from syn-to-post collisional brittle-ductile tectonic episodes. Mylonitic Abor volcanics in the thrust contacts are studied at several locations in the north and south of Puging in the Siang valley. Both the Abor volcanics and associated Rikor and Yinkiong Group of rocks preserve meso to micro-scale fabric asymmetries indicating that the thrust contacts are shear zones of brittle-ductile nature containing mylonitic textures of high shear strain. Two distinct hitherto unrecognised shear zones in the north and south of Puging are named as North Puging Shear Zone (NPSZ) and South Puging Shear Zone (SPSZ). The kinematic indicators along the thrust contact indicate oblique slip thrusting of the Rikor and Siyom thrust sheets above the Yinkiong Group of rocks. This paper provides field evidence proving that the compression due the Burmese plate made oblique slip thrusting and zones of mylonitised volcanics possible and associated metasediments were formed. The kinematic indicators in the NPSZ and SPSZ respectively indicate top-to-SSE and top-to-NNW sense of shears.

Due to rapid economic growth of the country in the last 25 years, particulate matter (PM) has become a topic of great interest in China. The rapid development of industry has led to an increase in the haze created by pollution, as well as by high levels of urbanization. In 2012, the Chinese National Ambient Air Quality Standard (NAAQS) imposed ‘more strict’ regulation on the PM concentrations, i.e., 35 and 70 μg/m3for annual PM2.5and PM10in average, respectively (Grade-II, GB3095-2012). The Pearson’s correlation coefficient was used to determine the linear relationship of pollution between pollution levels and weather conditions as well as the temporal and spatial variability among neighbouring cities. The goal of this paper was to investigate hourly mass concentration of PM2.5and PM10from June 1 to August 31, 2015 collected in the 11 largest cities of Gansu Province. This study has shown that the overall average concentrations of PM2.5and PM10in the study area were 26 and 66 μg/m3. In PM2.5episode days (when concentration was more than 75 μg/m3for 24 hrs), the average concentrations of PM2.5was 2–3 times higher as compared to non-episode days. There were no observed clear differences during the weekday/weekend PM and other air pollutants (SO2, NO2, CO and O3) in all the investigated cities.

The present paper examines hydroclimatic dynamics in southwestern Romania drylands, which is one of the country’s most heavily affected regions by climate change. The analysis focuses on two of the region’s representative catchments (Drincea and Desnatui), covers the past five decades (1961–2009), and is based on climate data (mean monthly and annual climatic water balance values – CWB, expressed in mm) and hydrological data (mean monthly and annual streamflow rate values – SFR, expressed in m3/s). The data were provided by five regional weather stations, i.e., by five gauging stations located within the two catchments. The analysis was conducted on three temporal scales (annual, seasonal and monthly), and used statistical methods, such as Mann–Kendall test/Sen’s slope method for trend analysis, and Spearman/Student test for the statistical association between climatic and hydrological parameters. The results indicated an overall increase in climatic water deficit, with direct effects on streamflow reduction. Statistically significant trends (climatic water deficit increase and streamflow decrease) were identified especially in spring (with maximum rate values of (−1.66 mm/yr)/(−81.3 mm/49 yrs), for the CWB, and (−0.02 m3/s/yr)/(−0.9 m3/s/49 yrs), for the SFR). In some cases (mainly in the autumn months) it was found that, while climatic water deficit has decreased, the streamflow rate has increased. Statistical correlations revealed the relationship between the considered hydroclimatic parameters, with a particularly high statistical significance in spring and summer. Weak and inverse correlations between climatic and hydrological parameters can be explained by the role of other factors controlling the streamflow, both natural (soil and lithology) and anthropogenic (wetland drainage, water body conversion, dam and reservoirs building).

This paper investigated the geotechnical properties of smectite-rich shale, and its implications as foundation material. Ten expansive shale samples were collected from foundation materials at Akpugo in Nkanu West L.G.A. of Enugu State, southeast Nigeria. Samples were subjected to grading, Atterberg limits-cum-compaction tests, slake durability, specific gravity, permeability, undrained triaxial tests and x-ray diffraction scan. Fines and sand contents of the soil samples range from 51–97% and 3–49% respectively. Liquid limit, plastic limit and plasticity index have average values of 60.7, 19.1 and 43.3% respectively. Linear shrinkage and free swell showed average of 16.3% and 76%. These results are indicative of predominant clay soil with high plasticity, compressibility and water holding capacity. XRD scan established presence of smectite and illite clay minerals, confirming soil high plasticity, capable of causing instability in foundation soil. The shale achieved maximum dry density range between 1.79 and 1.94 kg/m3at optimum moisture content range of 6.9–12.8%, indicating poor to fair foundation materials. The shale cohesion ranges from 15 to 30 kPa while the angle of friction ranges between 10° and 18°, signifying an average strength soil material. Samples slake durability index and specific gravity fall within 24–55% and 2.50–2.58 respectively, suggesting non-durable and weak soil. Permeability of the samples ranges between 7.36 ×10−6and 4.77 ×10−8cm/s which suggested low drainage capable of causing water-log at sites. Therefore, the shale could be generally classified as poor to fair foundation material, which on moisture influx experience reduction in strength due to deterioration of its constituent minerals, especially clay and cement materials during the lifespan of engineering structures. Authors therefore recommend modification of foundation soil, appropriate foundation design and good drainage control as ways of improving stability of engineering structures underlain by expansive shale.

The northwestern Guizhou in the Yangtze Craton of south China has a tremendous potential of shale gas resource. In this paper, we present results from major and trace elements, total organic carbon, mineralogical composition analysis and petrophysical parameters to characterise shale weathering features. Further, the differences of black shale between underground and outcrops have also been presented to examine the changes of black shale after weathering. Our results show that the trace elements of shale have varying degrees of loss in the weathering leaching process, both in Niutitang shale and Longmaxi shale, the loss of B, V, Ni, Cu, Zn and Ba is obvious, but the element migration quantity in the former is greater than in the latter. Decomposition of minerals such as pyrite, feldspar and calcite result in the leaching of Na, Ca, Mg and Fe. The loss rate of total organic carbon (TOC) in black shales ranges from 18% to 70% with an average of 43%; moreover, the loss of organic carbon in samples with high TOC content is larger than in those samples with low TOC content. Results following the testing of porosity and permeability show that porosity increases significantly after weathering but permeability changes little. Furthermore, the increment of porosity is greater in the Niutitang shale (with more sulphide minerals) than in the Longmaxi shale, suggesting that the oxidation of sulphide minerals may have led to the formation of an acidic environment, causing the other minerals in the black shale to weather more quickly, thus resulting in increased porosity. The content of clay minerals in the core samples is slightly lesser than the outcrop samples, but the TOC content in the core samples is greater and has a larger specific surface area. This suggest that the TOC content played a decisive role on the specific surface area of shale. In addition, changes in the black shale caused by the weathering process mainly depend on the mineral composition and the TOC content in shale. In this study, we try to establish relations between outcrop samples and core samples, in order to better understand the underground characteristics of shale reservoir.

In this paper, multivariate adaptive regression splines (MARS) was developed as a novel soft-computing technique for predicting longitudinal dispersion coefficient (DL) in rivers. As mentioned in the literature, experimental dataset related to DLwas collected and used for preparing MARS model. Results of MARS model were compared with multi-layer neural network model and empirical formulas. To define the most effective parameters on DL, the Gamma test was used. Performance of MARS model was assessed by calculation of standard error indices. Error indices showed that MARS model has suitable performance and is more accurate compared to multi-layer neural network model and empirical formulas. Results of the Gamma test and MARS model showed that flow depth (H) and ratio of the mean velocity to shear velocity (u/u∗) were the most effective parameters on the DL.

This paper presents a new algorithm to classify convective clouds and determine their intensity, based on cloud physical properties retrieved from the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The convective rainfall events at 15 min, 4 × 5 km spatial resolution from 2006 to 2012 are analysed over northern Algeria. The convective rain classification methodology makes use of the relationship between cloud spectral characteristics and cloud physical properties such as cloud water path (CWP), cloud phase (CP) and cloud top height (CTH). For this classification, a statistical method based on ‘naive Bayes classifier’ is applied. This is a simple probabilistic classifier based on applying ‘Bayes’ theorem with strong (naive) independent assumptions. For a 9-month period, the ability of SEVIRI to classify the rainfall intensity in the convective clouds is evaluated using weather radar over the northern Algeria. The results indicate an encouraging performance of the new algorithm for intensity differentiation of convective clouds using SEVIRI data.

The Eastern Mediterranean region has been exposed to drought episodes, which have been occurring more frequently during the last decades. The objective of the present paper is to study the precipitation regime of the Damascus (Mazzeh) meteoric station by analysing drought characteristics using the Standardized Precipitation Index (SPI) and comparing this with the drought in Cyprus. The cumulative drought conceptis proposed to characterize long-term hydrologic drought, which affects the shallow groundwater productivity in terms of quantity and quality. Gamma probability distribution was fitted to the long-term annual precipitation in Damascus from 1918–1919 to 2007–2008 (n= 90 years). Generally, a decreasing trend of 17% to the mean annual rainfall of Damascus and 13% to the mean annual rainfall of Cyprus was estimated between 1970 and 2000. The SPI identifies three major extended drought periods: (1) 9 years of severe drought (1954–1963) with an average 20% precipitation deficit per year compared to the mean. (2) 8 years of severe drought (1983–1991) with a 27% deficit per year on average. (3) 9 years of extreme drought (1993–2002) with a 31% deficit per year on average. The cumulative standardized precipitation index (SPI 30) demonstrates positive values for the first period and is indicative of having no effect on the global water balance. SPI 30 exhibits sensitive equilibrium with near zero values / a near zero value (±1.5) for the second period. For the third period, however, the SPI 30 decreases below −10 indicating an extreme hydrological drought that has negative consequences on the recent groundwater recharge. It is required to develop and implement a sustainable groundwater management strategy to reduce long-terms drought risks. Generally, the SPI 30 in Cyprus is parallel to that in Damascus with a 3–5 year delay. Thus, the central zone of the Eastern Mediterranean region is facing big challenges and has been suffering from three decades of moderate to severe hydrological drought (SPI 30=−5 to −10) causing a severe decrease in springs discharges of the region. Therefore, in order to reduce the climate change effects on water resources, it is necessary to adopt a sustainable proactive management plan during the frequent severe droughts.

Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagnetic storms on Earth. In this paper, we discuss the development of an artificial neural network-based model to study the precursor leading to intense and moderate geomagnetic storms, following halo coronal mass ejection (CME) and related interplanetary (IP) events. IP inputs were considered within a 5-day time window after the commencement of storm. The artificial neural network (ANN) model training, testing and validation datasets were constructed based on 110 halo CMEs (both full and partial halo and their properties) observed during the ascending phase of the 24th solar cycle between 2009 and 2014. The geomagnetic storm occurrence rate from halo CMEs is estimated at a probability of 79%, by this model.

This paper presents a comparison of ionospheric characteristic parameters obtained by a GPS network and three ionosondes at Mohe (122.4∘E, 53.5∘N, dip angle 70.983∘N), Zuolingzhen (114.6∘E, 30.5∘N, dip angle 46.350∘N), and Fuke (109.1∘E, 19.5∘N, dip angle 27.083∘N) located in China with an IRI model in the year 2011. Observed NmF2 and hmF2 values at the three stations are compared with IRI2007 and IRI2012 predictions, respectively. The results show that there are clear linear correlations between the observed values and the IRI model predicted values. The IRI model gives overestimations at the three stations mostly in 2011. For the NmF2 and hmF2 values, most of the results show that the IRI2012 predicted values are closer to the observed values compared with those of IRI2007. Additionally, the GPS TEC values derived from the Crustal Movement Observation Network of China (CMONOC) are compared with the IRI2012 predictions. From the results, it is evident that the IRI2012 model predictions follow the normal trend of diurnal variation of GPS measured TEC monthly means but do not reproduce the measured data well. The IRI2012 model overestimates electron density in the latter part of spring as well as the first half of autumn and winter and underestimates electron density in early spring and the latter part of autumn. Referring to GPS TEC, the precision of the IRI2012 model predicted TEC values is ∼5 TECU over China. It may also be noted that there are two discontinuities of IRI-TEC monthly means appearing in November and December of the year 2011. This brings a bias of ∼3 TECU of TEC values between two adjacent months.

Identification of sharp and discontinuous lithological boundaries from well log signal stemming from heterogeneous subsurface structures assumes a special significance in geo-exploration studies. Well log data acquired from various geological settings generally display nonstationary/nonlinear characteristics with varying wavelengths and frequencies. Modelling of such complex well-log signals using the conventional signal processing techniques either fails to catch-up abrupt boundaries or at the best, do not provide precise information on insidious lithological discontinuities. In this paper, we have proposed a new wavelet transform-based algorithm to model the abrupt discontinuous changes from well log data by taking care of nonstationary characteristics of the signal. Prior to applying the algorithm on the geophysical well data, we analyzed the distribution of wavelet coefficients using synthetic signal generated by the first order nonstationary auto-regressive model and then applied the method on actual well log dataset obtained from the KTB bore hole, Germany. Besides identifying the formation of layered boundaries, the underlying method also maps some additional formation boundaries, which were hitherto undetected at the KTB site. The results match well with known geological lithostratigraphy and will be useful for constraining the future model of KTB bore hole data.

The present paper is concerned with the propagation of torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half-space. We assume the quadratic inhomogeneity in rigidity and density in the lower half-space and irregularity is taken in the form of rectangle at the interface separating the layer from the lower half-space. The dispersion equation for torsional waves has been obtained in a closed form. Velocity equation is also obtained in the absence of irregularity. The study reveals that the presence of irregularity, initial stress, porosity, inhomogeneity and anisotropy factor in the dispersion equation approves the significant effect of these parameters in the propagation of torsional waves in porous medium. It has also been observed that for a uniform media, the velocity equation reduces to the classical result of Love wave.

This paper discusses an experimental approach to examine uranium exploration avenue over the geologically extended parts of Mahadek basin in Meghalaya, amid some of the environmental constraints. Study comprises periodic measurements of prevailing ambient gamma levels across 320 georeference points, in relation to the major litho units of Mahadek basin, covering 673 line km of Khasi Hills. Acquired sample data points were then analysed in geostatistical software (SurferTM) to develop analytical model of sample variogram having bearing on the uranium exploration in the area. Study findings have given encouraging surface indicators with mostly elevated gamma levels over the parts of West Khasi Hills. Delineated gamma anomalous zones are lithologically well correlated including to that of existing uranium occurrences in the basin. Identified anomalous zones over the parts of West Khasi Hills by this study work, are mainly associated with the Mahadek sandstone (Upper and Lower Mahadek) and Precambrian basement granites. Lower Mahadek sandstone is host rock for uranium mineralisation in the basin. Initial findings suggest with the closer spatial resolution (∼1 km) of sample data points, the approach adopted by the study work holds promising application in locating potential uranium exploration targets especially to the extended and inaccessible parts of the basin.

The Mogou syenite intruded into the Mesoproterozoic Xiong’er Group is the main lithostratigraphic unit, along the southern margin of the North China Craton (NCC). This paper reports zircon LA-ICP-MS data, whole-rock major and trace element compositions of late Triassic magmatic rocks in the Mogou syenite, in order to constrain the formation age of the Mogou syenite, research the origin and evolution of the magma and analyse the geodynamic setting of the Qinling Orogen (QO) in Late Triassic. These rocks consist of medium- to coarse-grained syenite and fine-grained quartz syenite. Zircon U–Pb dating yields a crystallization age of 226.5±2.7 Ma. The syenites are characterized by high SiO2(63.49–72.17%), alkali (K2O+Na2O of 11.18–15.38%) and potassium (K2O/Na2O of 2.88–28.11), are peralkaline or metaluminous (molar A/CNK of 0.87–1.02) and belong to shoshonite series. The syenites have ΣREE of 33.01–191.30 ppm, LREE/HREE of 14–20, (La/Yb)Nof 11–24, with LREE-rich distribution pattern and obvious differentiation between HREE and LREE. Eu anomalies are positive for the medium- to coarse-grained syenite and weakly negative for the fine-grained quartz syenite. In addition, the syenites are enriched in large-ion lithophile elements (Ba, K, Sr, and Pb) but depleted in high strength field elements (Ti, Ta, Nb, Zr, and Hf), and have high differentiation indices of 91.69–97.06. These geochemical features indicate that the primary magma of the Mogou syenite most likely originated from a mantle source with minor crustal component, and underwent a fractional crystallization process during its emplacement. The late Triassic A-type Moguo syenite along the southern margin of the NCC was generated in the late stage of the syn-collision event of QO, recording a transition period from compression to extension at around 227 Ma.