Tectonics and sedimentation of SW Sarawak basin,Malaysia, NW Borneo

Structurally SW Sarawak basin is a southward sloping basement characterized by passive margin tectonic that has undergone through varioius tectonic phases viz., Triassic extension, Cretaceous transpression and Oligo-Miocene compression. Rock types and sedimentation of deeper basin zone situated between Schwaner mountains block to the south and SW Sarawak basin to the north suggest progressive marine sedimentation. E-W trending Cretaceous carbonate platform (CCP) occurs in the SW Sarawak basin signify a shelf zone where shallow marine sedimentation progressed during Cretaceous transpression. Oligo-Miocene volcanics from subduction melts intercepted basin profusely forming northwest-southeast trending continental arc zone derived from partial melting of subducting slab underneath SW Sarawak basin. Back-arc extension prevailed during Oligo-Miocene and formed several extensional features. Oligo-Miocene subduction also resulted in closure and exhumation of Sri Aman marginal sea-basin to the east. SW Sarawak basin is further divided in two sub-basins viz., Senibong to the west and Kuching to the east separated by a northeast trending morphotectonic ridge that signify structural element formed due to shearing. Marine sedimentation progressed in these sub-basins mainly during Triassic–Jurassic while tidal and fluviatile sedimentation progressed during early to mid-Tertiary having total thickness of sediments about 9 km. Basin closure and exhumation is marked mainly by the formation of Cretaceous carbonate build-up that has been intruded and dissected by the Oligo-Miocene volcanics. Senibong and Kuching sub-basins are characterized by wide range of transpressive features, while, Sri Aman marginal sea-basin is characterized by oceanic assemblages, ophiolite, serpentinite and pillow basalt.     

The effects of orography in indochina on wind, cloud, and rainfall patterns during Typhoon Ketsana (2009)

The objective of this study is to i) investigate the effects of orography on the rainfall, wind, and cloud systems of the Typhoon Ketsana (2009) in Indochina, ii) determine rainfall distribution patterns and which parts of Indochina were most affected during Typhoon Ketsana, iii) identify trends in the cloud and rainfall distribution patterns and wind flow patterns in the synoptic scale on orographic effects during Typhoon Ketsana. Remote sensing techniques have been used to study the impacts of TCs. Using data from the remote sensing data such as Fengyun 2D (FY-2D) satellite, Global Digital Elevation Model (GDEM) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, wind information from the Navy Operational Global Atmospheric Prediction System (NOGAPS), and radiosonde data were applied in this study to determine the relationship of the typhoon with the orographic effect. This study provides examples of how the orographic effect is important to weather forecasters, as high mountain ranges were able to influence the distribution of the cloud, rainfall and even wind flow patterns during the typhoon season. This remote sensing technique allows tropical cyclones to be forecasted and their impacts to be defined, and it allows disaster zones to be determined.     

A study of gross alpha and beta measurements for thermal springs in Central Anatolia,Turkey

A screening of natural radioactivity content has been carried out in thermal water samples collected from surrounding of Central Anatolia, Turkey. The concentration levels of gross alpha and beta of 19 different samples has been determined using the low background gas-flow proportional counter. The measured gross alpha and beta activities in waters range from 0.11 to 16 Bq/L and 0.10 to 16.9 Bq/L, respectively. The measured values of gross alpha and beta concentrations are compared to previous studies in the literature and recommend WHO guideline activity concentration. The data resulting from the measurement have been statistically analyzed.     

Lithologic mapping of Aja granitic batholiths,Ha’il,Saudi Arabia,using remote sensing

In this study, remote sensing, field and petrographic investigation were integrated for lithological mapping of different granitic masses in Aja complex of Ha’il, Saudi Arabia. The Landsat-8 data were processed to spectrally discriminate variations within rock types using band combinations, band ratioing and principal component analysis (PCA) techniques. Results showed that band combination of the principal components could potentially distinguish the different rock units of Aja complex than any other transform. Field observations and petrographic identification were performed to validate remotely sensing data and to map different rock units. Alkali granites were accurately recorded on the peripheries of Aja Mountain. The present study demonstrates that remote sensing techniques could provide useful tools for mapping economic rock types, particularly in well-exposed arid regions.     

Engineering risk assessment on water structures under climate change effects

The increase in the average temperature in the lower atmosphere caused by climate change triggers changes in various elements of the hydrological cycle at different scales depending on location in the world. Although numerous published studies are concerned with the effect of climate change on hydrological elements such as temperature, precipitation, evaporation, wind, and runoff, unfortunately, the performance of water engineering structures is not taken into consideration. Nevertheless, as an integral part of the whole water resources systems, engineering structures such as dams, canals, culverts, and wells are also subject to climate change impacts. This examines the performance of engineering structures by taking into account how climate change impacts on the risk assessment formulation. For this purpose, the risk concept is redefined and the climate change impact is taken into account by a factor dependent on the positive or negative slope of the trend from the historical record. The risk levels are revised for 10-year, 50-year, and 100-year return periods. The application of the proposed methodology is given for precipitation records for three different meteorological stations in the southeastern European province of Turkey and for the same number of stations from central east-west belt over Saudi Arabia. It is observed that including the climate change factor in the risk calculation formulation generally leads to an increase in the return period and in the risk compared to conventional calculations. Therefore, it is recommended that rather than using the standard risk formulation, the simple, effective climate change risk approach, as suggested in this paper, be applied to future water engineering structure designs.     

Seismic hazard assessment and rheological implications: a case study selected for cities of Saudi Arabia along the eastern coast of Red Sea

A probabilistic approach is used to evaluate the seismic hazard for 12 strategic cities in Saudi Arabia along the eastern coast of Red Sea. The focal depth variations controlled by rheological characteristics are taken into account for hazard calculations, and its creditability is tested through sensitivity analysis for hazard results. This study presents a neo-probabilistic seismic hazard assessment methodology in which the focal depth distribution of earthquakes within seismogenic layer is divided into three depth slices. These depth slices are based upon rheological characteristic of seismogenic layer. The hazard results are obtained using this depth-slice methodology and conventional approach in which uniform distribution of seismicity within seismogenic layer is assumed. The sensitivity analysis culminated in underestimation of hazard values in higher frequencies for uniform distribution of seismicity within seismogenic layer. Foregoing the observations recorded above, it can be concluded that the exploitation of depth-slices biased by the rheology to calculate hazard is relatively preferable in the situations demanding safety measures.     

The importance of water in the ecosystem and marine crisis in the gulf region

Conclusions As developing countries expand both agricultural and industrial activities over the coming decade, sensitive management of the limited available freshwater resources will become increasingly important. If their supplies consist solely of ground water, then some water deficit countries could end up by mining a non-renewable resource as it takes many thousands of years to replenish deep fossil groundwater stocks. Conservation and careful husbandry of existing stocks must therefore be carried out if the growing human populations of arid lands are to be protected from famine and poverty.The arid zones may provide more than sufficient food in a sustainable system despite the harsh natural conditions. In arid areas rainfall is low, biological cycling is limited by low soil moisture and evapotranspiration is high. The absence of leaching by infiltration results in a large active pool of nutrients and the addition of water by irrigation allows this potential fertility to be realised. Given the high insolation of desert lands and a man-made continuous water supply it is possible to obtain 2–4 crop harvest a year. However, the success of any future development is ultimately in the hands of the governments who control the management of water resources.Until recently pollution of the sea was relatively localised. It has now become a problem globally around coasts and even affects the open ocean. Enclosed and semi-enclosed seas are most vulnerable to degradation of their ecosystems and the Golf region has proved to be no exception to this, sensitivity exacerbated by weak currents and political instability leading to increasing oil pollution.The pollution in the Gulf is at its most harmful in the biologically diverse and productive areas around coastlines where pollution tends to concentrate and where human welfare is also most at risk. The outbreak of cholera and other waterborne disease in Iraq immediately following the Gulf war highlights the exceptional reliance people throughout the Gulf States must place of fresh water supplies. Continuing political instability in the region and its associated environmental damage will not, therefore, only threaten wildlife or fisheries but may threaten human welfare as water supplies are limited or decline in quality and industry, agriculture and health all suffer the consequences.     

Alluvium thickness and stream order relationships in Wadi Al-Khanagah basin,Central Saudi Arabia

Conclusion This study represents a step forward in understanding the geomorphology of Wadi Al-Khanagah basin, especially the relationship between depositional landforms and drainage basin morphometry. Besides it has drawn the attention to the importance of establishing the relationships between landforms for rapid applied hydrogeomorphological studies in areas lacking systematic data base. To conclude, the established relationships between alluvium thickness and stream order in Wadi Al-Khanagah basin would give an adequate mean of predicting thickness of wadi alluvium and consequently the capacity of potential alluvium aquifers in the shield area of the Al-Quwayiyah region, in Central Saudi Arabia.