951 resultados para Subsurface drainage.


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Lake Nakuwa is one of the large lakes among the Kyoga drainage system lakes, located 132 km north east Off Jinja town, at 01° 091N 33° 21 1 E, an elevation 1037 m, surface area of 200 km2 and an average depth of 3.3 m. The lake is shared by the districts of Kamuli, Pallisa and the newly created district of Kaliro. howerever 80% of the landing sites are in Kaliro and less than 20% are shared between the districts of Kamuli and Pallisa. The lake is free of submerged and floating macrophytes, with lots of floating papyrus (sudds). Papyrus, hippo grass and reeds dominate the shoreline vegetation. Lake Nakuwa like the main lake Kyoga was stocked with the Nile perch and the tilapiine species namely Oreochromis niloticus, Oreochromis leucostictus and Tilapia zillii in the general stocking exercise of small lakes alild dams in the early 1970's.

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This study deals with seasonal variations, natural correlations and similarities of fouling assemblages on exposure panels in the Suez Bay during January 1992 to January 1993. Three main sources of pollutions flow into the bay; industrial waste products, domestic drainage of Suez city and ships' oil and refuse.The fouling assemblages on the test pan els after various periods (1, 2 and 3 months) belonged mainly to the algae (Ulva rigida), polychaetes (Hydroides elegans), Cirripedes (Balanus amphitrite) and amphipods. The fouling at the lst station was relatively more dense than at the 2nd station during the summer and autumn seasons. The lowest productivity was achieved at the 3rd station which was considered less polluted being offshore water. The overall paucity of fouling in the bay is because of the silt covering the submerged surfaces, particularly at the 2nd station, leading to the prevention of the settlements or establishment of fouling organisms. The seasonal changes in the intensity of fouling assemblages on submerged surfaces in seawater seems to be closely related to seasonal variations in water temperature. The great fouling communities on the buoys and long exposure panels showed a remarkable variety of species and density rather than on short term exposures, which were more dense during warmer months.

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The present paper investigates the occurrence and abundance of brachyuran larvae in the Manora Channel during August- December 1993. The fortnightly planktonic sampling was carried out in Manora Channel which is bordered by mangroves, during day time from surface and subsurface waters at shallow depth using Bongo net of 300 micron mesh size. Analysis of samples revealed presence of brachyuran larvae of 12 species belonging to 6 families. Of these 4 species are confirmed: Serenella indica, Dotilla blanfordi, Metopograpsus thukuhar and Clistocoeloma lanatum, 2 provisionally identified species are: Pilumnus ?karachiensis and Pinnotheres ?pisum, 2 species are identified upto generic level: Philyra sp. and Pinnotheres sp., and 1 Ocypodid species and 3 Xanthid species are identified upto family level. This study based on identification, occurrence and abundance of brachyuran larvae in the area, also gives percentage composition of brachyuran larvae collected during 1993, in the Manora Channel.

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The concentrations and distribution of particulate and dissolved heavy metals, viz: Cu, Zn, Pb, Cd, Fe and Mn have been determined seasonally during 2003 in water samples collected from the Suez Canal. The presented data clarifies that the metals exhibited clear differences in their distribution between particulate and dissolved forms. The concentration of particulate heavy metals ranged between 0.09-3.13, 0.57-15.02, 0.18-3.87, 0.02-0.73, 2.74-49.62 and 0.15-5.08 µg/L for Cu, Zn, Pb, Cd, Fe and Mn, respectively. In the same respect, these values for dissolved forms were 0.28-4.12, 0.57-9.08, 0.27-2.50, 0.02-1.24, 1.94-42.50 and 0.11-3.65 µg/L. The concentrations of particulate metals viz: Zn, Pb, Cd, Fe and Mn were high was compared to the dissolved forms. Dissolved copper, rather than particulate, showed the highest percentage of total copper. The particulate forms of Pb, Cd, Fe and Mn always had higher concentrations than the dissolved forms during the course of study except in the summer season. The northern part of the Suez Canal at Port Said showed mean concentrations of particulate and dissolved Cu=1.43 and 2.10, Zn=8.61 and 3.17, Pb=1.72 and 1.23, Cd=0.35 and 0.35, Fe= 23.49 and 15.83 and Mn=2.09 and 1.82 µg/L. These high concentrations may be attributed to the greater activities, particularly loading and unloading operations at Port Said harbour s industrial effluents and domestic drainage of Port Said city. In contrast, the Sinai side could be considered as reference site, as it was almost clean, i.e., without harmful outfalls, where Cu=0.16 and 0.56, Zn=2.14 and 0.94, Pb=6.29 and 3.44, Cd=0.055 and 0.088, Fe=6.29 and 3.44 and Mn=0.56 and 0.26 µg/L for particulate and dissolved metals respectively.

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A new species of cyprinid fish, Mekongina lancangensis, is described from the upper Mekong River drainage in Southern Yunnan, China. The new species is distinguished from the other species of Mekongina occurring in the lower Mekong River drainage by posse

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A new species of genus Microrasbora Annandale (1918), M. microphthalma, is described from the Nanwan River, a tributary of the Ruili River, Irrawaddy drainage, in southwest Yunnan province, China. This new species is the first record of the genus Microras

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Gymnodiptychus integrigymnatus is a critically endangered species endemic to the Gaoligongshan Mountains. It was thought to be only distributed in several headwater-streams of the Longchuanjiang River (west slope of the Gaoligongshan Mountains, belonging to the Irrawaddy River drainage). In recent years, dozens of G. integrigymnatus specimens have been collected in some streams on the east slope of the Gaoligongshan Mountains (the Salween drainage). We performed a morphological and genetic analyses (based on cytochrome b and D-loop) of the newly discovered populations of G. integrigymnatus to determine whether the degree of separation of these populations warrants species status. Our analysis from the cytochrome b gene revealed that nine individuals from the Irrawaddy drainage area and seven individuals from the Salween drainage area each have only one unique haplotype. The genetic distance between the two haplotypes is 1.97%. Our phylogenetic analysis revealed that G. integrigymnatus is closely related to highly specialized schizothoracine fishes. Analysis from the mitochondrial control region revealed that G. integrigymnatus has relatively high genetic diversity (pi was 0.00891 and h was 0.8714), and individuals from different river drainages do not share the same haplotypes. The AMOVA results indicated 87.27% genetic variability between the Salween and Irrawaddy populations. Phylogenetic trees show two major geographic groups corresponding to the river systems. We recommend that G. integrigymnatus should be considered as a high priority for protected species status in the Gaoligongshan Mountains National Nature Reserve, and that the area of the Gaoligongshan Mountains National Nature Reserve should be expanded to cover the entire distribution of G. integrigymnatus. Populations of G. integrigymnatus from different river systems should be treated as evolutionarily significant units.

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A new species of the genus Paracobitis, Paracobitis nanpanjiangensis is described from tributaries of the Nanpanjiang River drainage in China. It is distinguished from its congeners, except P. oligolepis and P. wujiangensis, by body scaleless or with rudimentary scales (caudal peduncle with several deeply embedded scales). It can be differentiated from P. wujiangensis by the complete lateral line (vs. incomplete), lower dorsal crest reaching the vertical of origin of anal fin (vs. shorter and higher dorsal crest not reaching the base of anal fin). It is distinguished from P. oligolepis by the following characters: branched dorsal fin with 81/2 (a few 91/2) rays (vs. 91/2), interspaces between bars in front of dorsal fin conspicuously thinner than those behind (vs. vermiform markings), dorsal head without vermiform markings or obscure (vs. clearly vermiform markings on dorsal head), vertebrae 4 + 36-38 (vs. 4 + 39-41).

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The Lake Victoria ecosystem has experienced changes associated fishing levels, arise in lake level of the 1960s, fish introductions and human activities in the drainage basin. Following the fish introductions of the 1950s and 1960s, niloticus has become the most abundant and commercially important species among the tilapiines. It appears to be the only species which has managed to co-exist with the Nile perch not only in Lake Victoria but also in Lake Kyoga where the two species were also introduced. There is, however, little published information on the biology and ecology of the species in the habitats. It has therefore been found necessary to initiate studies as have been developed for Lates niloticus, especially as the two species have assumed major role in the lake's fisheries.

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The Farm Pond, University of Ife, was impounded by the construction of a dam, below the confluence of two small streams, between March and July, 1967. The pond is located at an altitude of 122.4 m. 0.D., its outline is an indented trapezium occupying 445 dkrn' at maximum fill. Natural food is fed into the pond by its two inlets, and the pond is often coloured a darkish brown due to the abundance of plankton. In 1969, on the recommendation by the Fishery Division, Ministry of Agriculture and Natural Resources, Ibadan, about four standard head-pans of poultry droppings per 40 dkm2 per month were spread uniformly over the pond during 1969 and 1970. Also four pounds of triple superphosphate per acre per month were spread for a period of six months. The pond was drained a number of times in 1970. However, the lowest average level of 1.37 m was recorded in April, 1970, before drainage began; and the maximum depth of 5.7 m was recorded in September and October, 1970.

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This paper reports the application of Advanced Process Control (APC) techniques for improving the thermal energy efficiency of a paperboard-making process by regulating the Machine Direction (MD) profile of the basis weight and moisture content of the paper-board. A Model Predictive Controller (MPC) is designed so that the sheet moisture and basis weight tracking errors along with variations of the sheet moisture and basis weight are reduced. Also, the drainage is maximised through improved wet-end stability which can facilitate driving the sheet moisture set-point closer to its upper specification limit over time. It is shown that the proposed strategy can result in reducing steam usage by 8-10%. A simulation study based on a UK board machine is presented to show the effectiveness of the proposed technique. © 2011 Intl Journal of Adv Mechatr.

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This paper considers the taxonomy of most of the synodontis spp. present in the main drainage basins of West Africa. The first section consists of a key to the sixteen species known to occur in Lake Kainji. Nigeria. A second section considers species which are reputed to live in the area and therefore might occur in the lake. It is suggested that several of the latter group are synonymous with better known species.

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Over the last two or three years, the increasing costs of energy and worsening market conditions have focussed even greater attention within paper mills than before, on considering ways to improve efficiency and reduce the energy used in paper making. Arising from a multivariable understanding of paper machine operation, Advanced Process Control (APC) technology enables paper machine behaviour to be controlled in a more coherent way, using all the variables available for control. Furthermore, with the machine under better regulation and with more variables used in control, there is the opportunity to optimise machine operation, usually providing very striking multi-objective performance improvement benefits of a number of kinds. Traditional three term control technology does not offer this capability. The paper presents results from several different paper machine projects we have undertaken around the world. These projects have been aimed at improving machine stability, optimising chemicals usage and reducing energy use. On a brown paperboard machine in Australasia, APC has reduced specific steam usage by 10%, averaged across the grades; the controller has also provided a significant capacity to increase production. On a North American newsprint machine, the APC system has reduced steam usage by more than 10%, and it provides better control of colour and much improved wet end stability. The paper also outlines early results from two other performance improvement projects, each incorporating a different approach to reducing the energy used in paper making. The first of these two projects is focussed on optimising sheet drainage, aiming to present the dryer with a sheet having higher solids content than before. The second project aims to reduce specific steam usage by optimising the operation of the dryer hood.

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Soil liquefaction following large earthquakes is a major contributor to damage to infrastructure and economic loss, as borne out by the earthquakes in Japan and New Zealand in 2011. While extensive research has been conducted on soil liquefaction and our understanding of liquefaction has been advancing, several uncertainties remain. In this paper the basic premise that liquefaction is an 'undrained' event will be challenged. Evidence will be offered based on dynamic centrifuge tests to show that rapid settlements occur both in level ground and for shallow foundations. It will also be shown that the definition of liquefaction based on excess pore pressure generation and the subsequent classification of sites as liquefiable and non-liquefiable is not satisfactory, as centrifuge test data shows that both loose and dense sand sites produce significant excess pore pressure. Experimental evidence will be presented that shows that the permeability of sands increases rapidly at very low effective stresses to allow for rapid drainage to take place from liquefied soil. Based on these observations a micro-mechanical view of soil liquefaction that brings together the Critical State view of soil liquefaction and the importance of dynamic loading will be presented. © 2012 Indian Geotechnical Society.

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This paper considers how the provision of integrated household-level infrastructure – particularly water and environmental sanitation (including water supply, sewerage, roads, storm drainage and solid waste management) –can play a leading role in improving the conditions in slum settlements. Around 700 socio-economic interviews were carried out in India and South Africa to investigate an innovative approach called slum networking, which sees the strong correlation between slum locations and drainage paths as an opportunity for improving the wider urban environment. This recognition allows resources to be mobilised locally, thereby removing the need for external aid funding. The evidence from the 700 families shows that communities perceive water and sanitation inputs to be their top priority and are willing to contribute to the costs. If slum upgrading is led with access to integrated water and environmental sanitation at household level with community contributions to the cost of infrastructure, then slum communities subsequently invest considerably greater sums in improved housing and education, with longer term contributions to poverty alleviation, improvements in health and literacy and an increase in disposable incomes.