Conditional stochastic simulation model for spatial downscaling for assessing the effects of climate change on hydro-meteorological variables

The current study examines the recently proposed “bias correction and stochastic analogues” (BCSA) statistical spatial downscaling technique and attempts to improve it by conditioning coarse resolution data when generating replicates. While the BCSA method reproduces the statistical features of the observed fine data, this existing model does not replicate the observed coarse spatial pattern, and subsequently, the cross-correlation between the observed coarse data and downscaled fine data with the model cannot be preserved. To address the dissimilarity between the BCSA downscaled data and observed fine data, a new statistical spatial downscaling method, “conditional stochastic simulation with bias correction” (BCCS), which employs the conditional multivariate distribution and principal component analysis, is proposed. Gridded observed climate data of mean daily precipitation (mm/day) covering a month at 1/8° for a fine resolution and at 1° for a coarse resolution over Florida for the current and future periods were used to verify and cross-validate the proposed technique. The observed coarse and fine data cover the 50-year period from 1950 to1999, and the future RCP4.5 and RCP8.5 climate scenarios cover the 100-year period from 2000 to 2099. The verification and cross-validation results show that the proposed BCCS downscaling method serves as an effective alternative means of downscaling monthly precipitation levels to assess climate change effects on hydrological variables. The RCP4.5 and RCP8.5 GCM scenarios are successfully downscaled.     

Salt response of the freshwater microalga Scenedesmus obliquus (Turp.) Kutz is modulated by the algal growth phase

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of growth. The alga was cultured on BG11 growth medium and subjected to 0, 30, 100, and 200 mmol/L NaCl for a period of 20 d, during which algal cultures were harvested at 4-d intervals. The salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth phases. The sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to salinity. The concentrations of chlorophylls a and b, soluble sugars, proteins as well as those of K+ and Na+ in the alga exhibited peaks at the initiation of the exponential phase of growth, with increasing magnitude in proportion to the increase in the level of salinity. Nevertheless, whereas soluble sugars of the alga peaked at initiation of the exponential phase, starch concentration progressively increased with culture age, reaching saturation towards the stationary phase. Whereas the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for starch. The present results point to fast acclimation of S. obliquus to salt stress post a brief salt shock, utilizing soluble sugars, K+ and Na+ for osmotic adjustment. Increasing salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars, proteins, K + and Na + concentrations of the algal cells, particularly at the early stages of growth. However, the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.     

Tectonic evolution of an intraplate basin: the Lower Tagus Cenozoic Basin,Portugal

This article focuses on the reinterpretation of well, seismic reflection, magnetic, gravimetric, surface wave and geological surface data, together with the acquisition of seismic noise data to study the Lower Tagus Cenozoic Basin tectono‐sedimentary evolution. For the first time, the structure of the base of the basin in its distal and intermediate sectors is unravelled, which was previously only known in the areas covered by seismic reflection data (distal and small part of intermediate sectors). A complex geometry was found, with three subbasins delimited by NNE‐SSW faults and separated by WNW‐ESE to NW‐SE oriented horsts. In the area covered by seismic reflection data, four horizons were studied: top of the Upper Miocene, Lower to Middle Miocene top, the top of the Palaeogene and the base of Cenozoic. Seismic data show that the major filling of the basin occurred during Upper Miocene. The fault pattern affecting Neogene and Palaeogene units derived here points to that of a polyphasic basin. In the Palaeogene, the Vila Franca de Xira (VFX) and a NNE‐SSW trending previously unknown structure (ABC fault zone) probably acted as the major strike‐slip fault zones of the releasing bend of a pull‐apart basin, which produced a WNW‐ESE to NW‐SE fault system with transtensional kinematic. During the Neogene, as the stress regime rotated anticlockwise to the present NW‐SE to WNW‐ESE orientation, the VFX and Azambuja fault zones acted as the major transpressive fault zones and Mesozoic rocks overthrusted Miocene sediments. The reactivation of WNW‐ESE to NW‐SE fault systems with a dextral strike‐slip component generated a series of horsts and grabens and the partitioning of the basin into several subbasins. Therefore, we propose a polyphasic model for the area, with the formation of an early pull‐apart basin during the Palaeogene caused by an Iberia–Eurasia plates collision that later evolved into an incipient foreland basin along the Neogene due to a NW‐SE to WNE‐ESE oriented Iberia–Nubia convergence. This convergence is producing uplift in the area since the Quaternary except for the Tagus estuary subbasin around the VFX fault, where subsidence is observed. This may be due to the locking or the development of a larger component of strike‐slip movement of the NNE‐SSW to N‐S thrust fault system with the exception of the VFX fault, which is more favourably oriented to the maximum compressive stress.     

"Biostratigraphy and Paleoecology of Paleocene/Eocene (P/E) interval of some geological sections in Central Egypt"

The Paleocene/Eocene boundary intervals were studied in three outcrops along the Nile Valley: Gabal Taramsa, Gabal Qreiya, and Gabal Nag El Quda in Qena and Esna regions. The planktonic and benthic foraminifera have been examined. The qualitative study of planktonic foraminifera distinguishes eight planktonic biozones from (P4 and P5) Paleocene age to (E1, E2, E3, E4, E5, and E6) Early Eocene age. The analysis of quantitative distribution patterns of benthic foraminifera allows the reconstruction of the paleoenvironmental settings in the studied area. The disappearance or scarce appearance of deeper-water benthic foraminifera (Angulogavelinella avnimelechi and Gavelinella rubiginosus) and increasing dominance of shallow-marine taxa (Buliminides, Loxostomoides applinae) indicate deposition in shallow water environments. The benthic foraminiferal assemblages which dominated by Loxostomoides applinae, Buliminids, and Lenticulina indicate Dysoxic conditions and maximum food levels. The species of mid-way type fauna dominate the assemblages of the studied area; the species of Velasco-type fauna are very rare.     

Stochastic differential dynamic programming for multi-reservoir system control

: As with all dynamic programming formulations, differential dynamic programming (DDP) successfully exploits the sequential decision structure of multi-reservoir optimization problems, overcomes difficulties with the nonconvexity of energy production functions for hydropower systems, and provides optimal feedback release policies. DDP is particularly well suited to optimizing large-scale multi-reservoir systems due to its relative insensitivity to state-space dimensionality. This advantage of DDP encourages expansion of the state vector to include additional multi-lag hydrologic information and/or future inflow forecasts in developing optimal reservoir release policies. Unfortunately, attempts at extending DDP to the stochastic case have not been entirely successful. A modified stochastic DDP algorithm is presented which overcomes difficulties in previous formulations. Application of the algorithm to a four-reservoir hydropower system demonstrates its capabilities as an efficient approach to solving stochastic multi-reservoir optimization problems. The algorithm is also applied to a single reservoir problem with inclusion of multi-lag hydrologic information in the state vector. Results provide evidence of significant benefits in direct inclusion of expanded hydrologic state information in optimal feedback release policies.     

Tropical residual soil as compacted soil liners

A series of laboratory tests was conducted on a tropical residual soil, which is widespread and readily available over a considerable part of Peninsular Malaysia, to assess whether it could be compacted as hydraulic barriers in waste disposal landfills. Index properties, swelling potential, cation exchange capacity (CEC), compaction characteristics, and hydraulic conductivity of the soil indicate that it is inorganic, very plastic, inactive (activity <0.75), moderately expansive (modified free swell index is about 3.06), and of fair attenuation capacity (for inorganic contaminants). For hydraulic conductivity measurement, the soil was compacted in rigid-wall permeameter moulds at a variety of water contents and compactive efforts and then permeated with de-aired tap water. The results of hydraulic conductivity tests illustrate that hydraulic conductivity lower than 1×10^–7 cm/s can be achieved using a broad range of water contents and compactive efforts, including water contents dry of optimum. Its shrinkage and strength properties show that it has minimal potential to shrinkage and has adequate strength to support the overburden pressure imposes by the waste body. These findings suggest that the residual soil can be potentially utilized as compacted soil liner material.     

A generalized conditional heteroscedastic model for temperature downscaling

This study describes a method for deriving the time varying second order moment, or heteroscedasticity, of local daily temperature and its association to large Coupled Canadian General Circulation Models predictors. This is carried out by applying a multivariate generalized autoregressive conditional heteroscedasticity (MGARCH) approach to construct the conditional variance–covariance structure between General Circulation Models (GCMs) predictors and maximum and minimum temperature time series during 1980–2000. Two MGARCH specifications namely diagonal VECH and dynamic conditional correlation (DCC) are applied and 25 GCM predictors were selected for a bivariate temperature heteroscedastic modeling. It is observed that the conditional covariance between predictors and temperature is not very strong and mostly depends on the interaction between the random process governing temporal variation of predictors and predictants. The DCC model reveals a time varying conditional correlation between GCM predictors and temperature time series. No remarkable increasing or decreasing change is observed for correlation coefficients between GCM predictors and observed temperature during 1980–2000 while weak winter–summer seasonality is clear for both conditional covariance and correlation. Furthermore, the stationarity and nonlinearity Kwiatkowski–Phillips–Schmidt–Shin (KPSS) and Brock–Dechert–Scheinkman (BDS) tests showed that GCM predictors, temperature and their conditional correlation time series are nonlinear but stationary during 1980–2000 according to BDS and KPSS test results. However, the degree of nonlinearity of temperature time series is higher than most of the GCM predictors.     

Magneto-seismic studies of the eastern Qattara Depression,Northwestern desert,Egypt

The potential field data are considered the main supporting factor in the geophysical exploration process for detecting and evaluating the subsurface structures. Therefore, a detailed land magnetic survey was performed in an area subjected to seismic investigations. The main target of this study was to detect the deeper subsurface structures and to investigate their possible relationships with earthquake activity.The RTP aeromagnetic map was used to detect the regional extension of the structures interpreted from the land magnetic survey. The RTP land and aeromagnetic maps were interpreted by the filtering technique, least-squares separations, tectonic trend analysis, spectral analysis, Werner method, Euler method, and 2D techniques. The results show that the main tectonic trends are 35° N–45° W, 45° N–65° E, E–W, and Aqaba.Moreover, two seismic lines, WQ85-31B and 127, were interpreted, and their location was matched with the deduced tectonic map. The results show great matching between the location of the faults deduced from both the geomagnetic and seismic data. They agree completely with the well logging data.Furthermore, these structures are correlated with the earthquake activities recorded by the Egyptian National Seismological Network (ENSN). The correlation implies that the studied area is more stable than other adjacent areas in the northern parts of Egypt close to the Mediterranean Sea and the Nile River Delta.     

Strong earthquakes associated with high amplitude daily geomagnetic variations

In this work, we attempt to quantify forces that result from the interaction between the induced Sq-variation currents in the Earth’s lithosphere and the regional Earth’s magnetic field, in order to assess its influence on the tectonic stress field and on seismic activity. The study area is the Sinai Peninsula, a seismically active region where both seismic and magnetic data are available. We show that both short-term and long-term magnetic changes correlate with the seismic activity extending to this area in other previous studies. We also analyze a set of large earthquakes and magnetic data from observatories around the world to deduce a relationship between earthquake magnitude and maximum distance up to which precursory variations of the magnetic field are observed.