The efficiency of detention reservoirs for flood control on the Jafar Abad River in Golestan province (Iran)

In order to investigate the effect of detention reservoirs on flood, the precipitation-runoff process as well as the reservoir routing was simulated with the HEC-HMS software. The model was run under four different scenarios (without a reservoir and with an empty, half-full, and full reservoir) and with different return periods of from 2 to 100 years in the Jafar Abad River basin, Golestan province, Iran. The statistical analysis of the results was based on one-way analysis of variance. To study the effect of reservoirs, two indices were used: the Flood Attenuation Rate (FAR) and Storage Ratio (SR). The results indicated that the construction of detention reservoirs leads to the decrease in peak discharge and the volume of flood that leaves the reservoir and postpones the incidence of the peak discharge. The influence of the reservoir diminishes with the prolongation of the return period. The maximum level of flood volume reduction for empty, half-full, and full reservoirs was 61.1, 33.2, and 0.8%, respectively, and for the peak discharge was 63.9, 32.8, and 6.6%, respectively. The maximum value of FAR for reservoirs under empty, half-full, and full conditions were 26, 19, and 7%, respectively. Similarly, the maximum SR for the empty and half-full reservoirs was 14 and 5%, respectively, thus showing the efficiency of reservoirs in flood control. Also, the results demonstrate that the efficiency of reservoirs in flood control not only depends on the reservoir volume and the amount of flood, but also on the geometric properties of the reservoir and weir.     

Origin of well-rounded gravels in glacial deposits from Brøggerhalvøya, northwest Spitsbergen: potential problems caused by sediment reworking in the glacial environment

Well-rounded gravels are described from moraine-mound complexes, diamicton forefields and modern englacial thrusts at the margins of four glaciers on the northern side of Brøggerhalvøya, northwest Spitsbergen. Their shape charcteristics are compared with modern and fossil glacigenic, modern beach and Early Weichselian beach gravels from this peninsula. The best discriminators of the well-rounded gravels have been found to be the percentage-frequency roundness histograms, the roundness mid-point and roundness range diagrams and the sphericity-roundness plots. It is concluded that the gravels have been derived by englacial thrusting from Early Weichselian or last interglacial beaches in the inner parts of the fjord and in the low level cirques when sea level reached at least 50m a.s.l. and deposited the beach gravels. The discrimination between gravel in basal diamictons, proglacial outwash and modern beaches is difficult as the reworking has resulted in little particle shape change. The potential major problem caused by reworking in the glacial environment is emphasised. especially when clast shape comparisons from modern environments to older sediments are used.     

Computer processing of LANDSAT-1 data and imagery generation

LANDSAT-1 (ERTS-1) data of the complete scene, 1218-04320, covering an area 185 Km x 185 Km in the Godavari Valley, India was computer processed in the Computer Division of the Oil and Natural Gas Commissíon to produce an imagery of readily recognizable land forms. Comparison with the original maps supplied by NASA showed an amazing agreement in quality. Computer oriented data enhancement techniques were developed and the data was reprocessed with the help of these techniques. The resulting imagery reveal an improvement over the originals. The computer software package developed to-date comprises nine different programmes to process the LANDSAT data on the IBM 360, 370 series.     

A Customization of the Arc Marine Data Model to Support Whale Tracking via Satellite Telemetry

The Arc Marine data model is a generalized template to guide the implementation of geographic information systems (GIS) projects in the marine environment. It developed out of a collaborative process involving research and industry shareholders in coastal and marine research. This template models and attempts to standardize common ocean and coastal data types to facilitate data sharing and analytical tool development. In this study, Arc Marine is extended from its core model to fit the research goals of the whale satellite-telemetry-tagging program of the Oregon State University Marine Mammal Institute (MMI). The study sought the best customization of the generic Arc Marine data model to enhance the key advantages of satellite telemetry for mapping the distribution and movement of endangered marine mammal species. It was found that three new groups of object classes were needed (Animal, Telemetry, and Operations). Further customization involved the development of a comprehensive framework for animal tracking with Argos satellite telemetry data. A new multidimensional data cube model was also devised, showing how this extension of Arc Marine serves as an appropriate target schema for the application of on-line analytical processing (OLAP) tools and spatial data mining of satellite telemetry tracking datasets.     

Characterization of beryl (aquamarine variety) from pegmatites of Minas Gerais,Brazil

Eight samples of the beryl variety aquamarine were selected from four pegmatites in the Governador Valadares and Araçuaí regions in northeastern Minas Gerais State, Brazil. These samples were fully characterized by chemical analysis, infrared and UV-visible spectroscopy, thermal analyses, and high-temperature X-ray diffraction (from room temperature up to 800 °C). Several physical and chemical properties of beryl were found to depend on the amount of water and ions residing in the structural channels. The thermal expansion coefficients from room temperature to about 800 °C are temperature-independent, with αa ? ?3.2 × 10^?6 ° C^?1 and αc ? ?8.7 × 10^?6 ° C^?1. The contraction of both a and c unit-cell parameters with increasing temperature and the shift of the infrared band centered at about 1200 cm^?1 were tentatively ascribed to interactions between channel water and the silicate rings.The color of beryl seems to be dictated by the relative proportions of Fe³⁺ in the octahedralsites and of fe²⁺ in the channels. Thus, deep-blue samples have little Fe³⁺, whereas greener samples have more Fe³⁺ or less channel Fe²⁺.     

Contrast in life histories of exploited fishes and ecosystem structures in coastal waters off west Canada and east Korea

By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by short-lived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late-1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.     

Wind sedimentation in the Jafurah sand sea, Saudi Arabia

The Jafurah sand sea of the Eastern Province of Saudi Arabia extends along the Arabian Gulf coastline from Kuwait in the north to the Rub Al Khali in the south, a distance of about 800 km. Sand drifts southward to south-eastward from regions of high wind energy in the north to low wind energy in the south. The aeolian landscape is zoned, with areas of deflation, transport and deposition from north to south. Drift rates in the zone of transport, near Abqaiq, range from 2 m³ m-w^-1 yr^-1 on sabkhas, to 29 m³ m-w^-1 yr^-1 on the crests of dunes. Average drift rates of approximately 18 m³ m-w^-1 yr^-1 observed during the study can cause about 1 m of accumulation per 5500 yr in a 100 km zone of deposition downwind, not including the bulk transport represented by the forward advance of dunes. Dune advance ranged from 23 m (2.9 m high dune) to 3 m (23 m high dune) during April-October 1980. The study area consists of dune, interdune, sand sheet and siliciclastic sabkha terrains, each of which is characterized by differing drift rates, and differing rates of erosion or deposition. Sedimentation occurs by lateral movement of dunes and interdunes, and vertical accretion by sand sheets and sabkhas.     

Spectral factorization technique for estimation of an ARMA operator for multichannel deconvolution of seismic data

A new spectral factorization method is presented for the estimation of a causal as well as a causally invertible ARMA operator from the correlation sequence of seismic traces. The method has been implemented for multichannel deconvolution of seismic traces with the aim of exploiting the trace-to-trace correlation that exists within seismograms. A layered earth model with a small reflectivity sequence has been considered, and the seismic traces have been considered as the output of a linear system driven by white noise reflection coefficient sequences. The present method is the concatenation of three algorithms, namely Kung's method for state variable ( F , G , H ) realization using a singular value decomposition (SVD) algorithm, Faurre's technique for computation of the strong spectral factor and Leverrier's algorithm for ARMA representation of the spectral factor. The inverted ARMA operator is used as a recursive filter for deconvolution of seismic traces. In the example shown, two traces with a covariance sequence of 160 ms length have been considered for multichannel deconvolution of stacked seismic traces. The results presented, when compared with those obtained from a conventional deconvolution algorithm, have shown encouraging prospects.