Studies on siltation in cochin harbour dynamics of suspensate

The present study is an attempt to elucidate the sedimentation regime of the harbour and its environment. These investigations include detailed studies on the hydrography' of the harbour region of the estuary, estuarine circulation, spatial and temporal variations of the amount and texture of bottom sediments. A note on the dredging is also given in the Annexure .The thesis is presented in six chapters

Macrobenthos And Its Relation To Ecosystem Dynamics In The Cochin Estuary

Cochin estuary is a shallow brackish water body situated on the south west coast of India. It is a tropical positive estuary extending between 90 40’ and 100 12’ N and 760 10’and 760 30’ E with its northern boundary at Azhikode and southern boundary at Thannermukkom bund.The abundance of benthic fauna in an ecosystem shows the close relationship to its environment and reflects the characteristics of an ecological niche. Seasonal and monthly variations in the distribution of macrobenthos in relation to sediment characteristics were conducted in Cochin estuary from 2009-10 periods. Oxidation-reduction potential showed reducing trends that affected the distribution and diversity of fauna. Seasonal variations in water quality and river discharge pattern affected the faunal composition in the different stations. Sewage mixing was the principal source of organic pollution in the Cochin estuary. The sediment pH was generally on the alkaline side ranging from 4.99 at St.9 and 8.33 at St.1.The Eh ranged from -11mV at St.3 to -625mV at St.2.The temperature varied from 260C to 320C in the estuary. The moisture content ranged from 1.63 to 12.155%, that of organic carbon from 0 09 at St. 6 to 4.29% at St.9 and that of organic matter from 0.16 to 7.39%. Seasonally, the average of Eh was highest during the monsoon (156.22 mV) and in the pre monsoon (140.94 mV). The average pH for the 9 study stations was 7.68 during monsoon period and 7.08 during post monsoon. Based on group wise seasonal analysis, the average mean abundance was maximum for polychaetes (43.47) followed by nematodes (33.62), crustaceans (21.62), molluscs (11.94) and Pisces (0.05) in the estuary. Monsoon season was most favourable for benthic faunal abundance followed by the post monsoon period in the study. The series of human interventions like dredging, discharge of industrial effluents, urbanisation and related aspects had a strong influence on the distribution, abundance of benthic macrofauna in the wetland.

Estudio de la competitividad e internacionalización de la navegabilidad del río Magdalena

La infraestructura colombiana es uno de los mayores problemas a los cuales se enfrenta el comercio en el país, debido a la situación en que se encuentran las carreteras, la falta de vías fluviales, férreas y las condiciones geográficas que se presentan. Es por esto que el gobierno plantea dentro del Plan Nacional de Desarrollo (PND), inversiones en infraestructura para mejorar las condiciones de esta, permitiendo atender las demandas de comercio. Uno de los mayores proyectos a los que se enfrenta el país es la “recuperación de la navegabilidad del río Magdalena” con el cual se pretenden ahorrar costos de transporte, optimizar las cantidades trasladadas y hacer efectivo y eficiente el comercio en Colombia. El presente trabajo, destaca la importancia que tiene esta vía fluvial, las ventajas que se obtendrán al recuperar el río y las obras a realizar para mejorar sus condiciones actuales.

Limnological characteristics and zooplankton community structure of Mediterranean coastal lagoons undergoing restoration

Entre 1999 i 2003 es va desenvolupar un projecte Life de restauració a la maresma de La Pletera, afectada per un pla urbanització, i a la llacuna del Ter Vell, amb un elevat grau d'eutròfia (aiguamolls del Baix Ter, NE Península Ibèrica). L'objectiu d'aquesta tesi és establir el funcionament d'ambdós ecosistemes, analitzar-ne la problemàtica ambiental i avaluar els efectes de la restauració. A la maresma de la Pletera, es va analitzar el paper de la hidrologia en la composició i dinàmica dels nutrients i del zooplàncton en cinc llacunes, tres de les quals havien estat creades dins el projecte de restauració com a nous refugis per una espècie de peix amenaçada (Aphanius iberus). La hidrologia es va caracteritzar per un llarg període de confinament sense entrades d'aigua, interromput de manera irregular per inundacions puntuals. La dinàmica del nitrogen inorgànic es va relacionar amb les entrades d'aigua, mentre que la del fòsfor, del nitrogen total i de la matèria orgànica es va relacionar amb els processos d'acumulació i reciclatge intern durant el confinament. El zooplàncton es va analitzar mitjançant la combinació d'aproximacions taxonòmiques i de mides. L'estructura de mides de la comunitat es va veure més afectada per les interaccions tròfiques (depredació i competència) mentre que l'estructura taxonòmica va ser més sensible a factors abiòtics (nutrients). El ràpid creixement de la població A. iberus en les noves llacunes va suggerir que aquestes havien proporcionat l'hàbitat adequat per a l'espècie, almenys a curt termini. Les actuacions de restauració a la llacuna del Ter Vell es van centrar en la millora de la qualitat de l'aigua mitjançant (1) la construcció d'uns aiguamolls per depurar l'aigua d'entrada i (2) el dragat del sediment en diversos punts. Simultàniament a la restauració, però de forma independent, la gestió agrícola de l'aigua va reduir dràsticament el cabal d'entrada d'aigua dolça a la llacuna, provocant un canvi en el règim hídric. Es van analitzar els efectes a curt termini d'aquest canvi sobre la limnologia i el zooplàncton de la llacuna. Abans del canvi, la hidrologia era artificial ja que s'havia prolongat l'entrada d'aigua dolça d'acord amb la demanda agrícola, i per tant la llacuna presentava una elevada taxa de renovació de l'aigua i majors concentracions de nutrients. Després del canvi, la hidrologia va dependre més del clima, es van reduir les entrades d'aigua i es va allargar el període de confinament. La composició y dinàmica dels nutrients va tendir a assemblar-se a l'observada a les llacunes de la maresma, mentre que la comunitat del zooplàncton no ho va fer. L'estat ecològic de la llacuna va millorar després del canvi en el règim hídric.

Terrestrial implications for the maritime geoarchaeological resource: A view from the Lower Palaeolithic

Stone tools and faunal remains have been recovered from the English Channel and the North Sea through trawling, dredging for aggregates, channel clearance, and coring. These finds highlight the potential for a maritime Lower Palaeolithic archaeological resource. It is proposed here that any Lower Palaeolithic artefacts, faunal remains, and sediments deposited in the maritime zone during dry, low-stand phases were once (and may still be) contextually similar to their counterparts in the terrestrial Lower Palaeolithic records of north-western Europe. Given these similarities, can interpretive models and analytical frameworks developed for terrestrial archaeology be profitably applied to an assessment of the potential value of any maritime resource? The terrestrial geoarchaeological resource for the Lower Palaeolithic is dominated by artefacts and ecofacts that have been fluvially reworked. The spatio-temporal resolution of these data varies from entire river valleys and marine isotope stages to river channel gravel bar surfaces and decadal timescales, thus supporting a variety of questions and approaches. However, the structure of the terrestrial resource also highlights two fundamental limitations in current maritime knowledge that can restrict the application of terrestrial approaches to any potential maritime resource: (i) how have the repetitive transgressions and regressions of the Middle and Late Pleistocene modified the terrace landforms and sediments associated with the river systems of the English Channel and southern North Sea basins?; and (ii) do the surviving submerged terrace landforms and fluvial sedimentary deposits support robust geochronological models, as is the case with the classical terrestrial terrace sequences? This paper highlights potential approaches to these questions, and concludes that the fluvial palaeogeography, Pleistocene fossils, and potential Lower Palaeolithic artefacts of the maritime geoarchaeological resource can be profitably investigated in future as derived, low-resolution data sets, facilitating questions of colonisation, occupation, demography, and material culture.

Evaluation of field wetlands for mitigation of diffuse pollution from agriculture: sediment retention, cost and effectiveness

Diffuse pollution, and the contribution from agriculture in particular, has become increasingly important as pollution from point sources has been addressed by wastewater treatment. Land management approaches, such as construction of field wetlands, provide one group of mitigation options available to farmers. Although field wetlands are widely used for diffuse pollution control in temperate environments worldwide, there is a shortage of evidence for the effectiveness and viability of these mitigation options in the UK. The Mitigation Options for Phosphorus and Sediment Project aims to make recommendations regarding the design and effectiveness of field wetlands for diffuse pollution control in UK landscapes. Ten wetlands have been built on four farms in Cumbria and Leicestershire. This paper focuses on sediment retention within the wetlands, estimated from annual sediment surveys in the first two years, and discusses establishment costs. It is clear that the wetlands are effective in trapping a substantial amount of sediment. Estimates of annual sediment retention suggest higher trapping rates at sandy sites (0.5–6 t ha�1 yr�1), compared to silty sites (0.02–0.4 t ha�1 yr�1) and clay sites (0.01–0.07 t ha�1 yr�1). Establishment costs for the wetlands ranged from £280 to £3100 and depended more on site specific factors, such as fencing and gateways on livestock farms, rather than on wetland size or design. Wetlands with lower trapping rates would also have lower maintenance costs, as dredging would be required less frequently. The results indicate that field wetlands show promise for inclusion in agri-environment schemes, particularly if capital payments can be provided for establishment, to encourage uptake of these multi-functional features.

Hydrology and geomorphology of the Upper White Nile lakes and their relevance for water resources management in the Nile basin

Remote sensing data and digital elevation models were utilized to extract the catchment hydrological parameters and to delineate storage areas for the Ugandan Equatorial Lakes region. Available rainfall/discharge data are integrated with these morphometric data to construct a hydrological model that simulates the water balance of the different interconnected basins and enables the impact of potential management options to be examined. The total annual discharges of the basins are generally very low (less than 7% of the total annual rainfall). The basin of the shallow (5 m deep) Lake Kioga makes only a minor hydrological contribution compared with other Equatorial Lakes, because most of the overflow from Lake Victoria basin into Lake Kioga is lost by evaporation and evapotranspiration. The discharge from Lake Kioga could be significantly increased by draining the swamps through dredging and deepening certain channel reaches. Development of hydropower dams on the Equatorial Lakes will have an adverse impact on the annual water discharge downstream, including the occasional reduction of flow required for filling up to designed storage capacities and permanently increasing the surface areas of water that is exposed to evaporation. On the basis of modelling studies, alternative sites are proposed for hydropower development and water storage schemes

Simulation Of Shoreline Changes Along Muthalapozhy Harbour, India

A study of Muthalapozhy fishing harbour, located in south India, was conducted for simulating shoreline changes using LITPACK modelling tool. The analysis shows that the estimated advancement in shoreline is of the order of 45 m/year initially, which gradually reduces to 25 m/year. It was also found that the coastline advances more during the south-west monsoon (i.e. June to September) season. Simulation of breakwaters shows that the length of the breakwater should be increased by 200 m for south breakwater and 70 m for north breakwater to keep the channel operational without dredging till 2016. The results of the simulated shoreline will help the port managers for maintaining the channel round the year.

Ecotoxicological assessment of sediments from the Port of Santos and the disposal sites of dredged material

A dragagem dos sedimentos do Canal de Santos é necessária para permitir o trânsito de navios que operam no Porto de Santos. As áreas de disposição do material dragado estão situadas na zona costeira, em frente à Baía de Santos. Este estudo visou avaliar a qualidade dos sedimentos do Canal de Santos e das áreas de disposição atuais e antigas, utilizando testes de toxicidade de sedimento integral com anfípodos e de toxicidade de elutriatos com embriões de ouriço do mar. As amostras do Canal de Santos foram consideradas as mais tóxicas: todas as amostras dessa área foram consideradas significativamente tóxicas. Além disso, algumas amostras das áreas de disposição exibiram toxicidade. Os resultados mostraram, portanto, que os sedimentos apresentam evidências de degradação em sua qualidade, porém novos estudos devem ser conduzidos visando determinar as relações entre contaminação e toxicidade. Os resultados sugerem ainda que a disposição dos sedimentos dragados deva ser reavaliada.

Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil

Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecem) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. (C) 2012 Elsevier Ltd. All rights reserved.

Harmonised framework for ecological risk assessment of sediments from ports and estuarine zones of North and South Atlantic

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Batimetria fluvial estimada com dados orbitais: Estudo de caso no alto curso do rio Paraguai com o sensor ASTER

The Paraguay River is the main tributary of the Paraná River and has an extension of 1.693 km in Brazilian territory. The navigability conditions are very important for the regional economy because most of the central-west Brazilian agricultural and mineral production is transported by the Paraguay waterway. Increased sedimentation along the channel requires continuous dredging to waterway maintenance. Systematic bathymetric surveys are periodically carried out in order to check depth condition along the channel using echo-sounding devices. In this paper, digital image processing and geostatistical analysis methods were used to analyze the applicability of the ASTER sensor to estimate channel depths in a segment of the upper Paraguay River. The results were compared with field data in order to choose the band with better adjustment and to evaluate the standard deviation. Comparing the VNIR bands, the best fit was presented by the red wavelength (band 2; 0,63 - 0,69 μm), showing a good representation of the channel depths shallow than 1,7 m. Applying geostatistical methods, the model accuracy was enhanced from 43 cm to 36 cm and undesired components were slacked. It was concluded that the digital number of band 2, converted to bathymetry information allows a good estimation of river depths and channel morphology.

Integrated quality assessment of sediments from harbour areas in Santos-São Vicente Estuarine System, Southern Brazil

Santos-São Vicente Estuarine System is a highly populated coastal zone in Brazil and where it is located the major port of Latin America. Historically, port activities, industrial and domestic effluents discharges have constituted the main sources of contaminants to estuarine system. This study aimed to assess the recent status of sediment quality from 5 zones of Port of Santos by applying a lines-of-evidence approach through integrating results of: (1) acute toxicity of whole sediment and chronic toxicity of liquid phases; (2) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes and butyltins; (3) benthic community descriptors. Results revealed a gradient of increasing contamination for metals and organic compounds, alongside with their geochemical carriers. Sediment liquid phases were more toxic compared to whole sediment. Low number of species and individuals indicated the impoverishment of benthic community. The use of site-specific sediment quality guidelines was more appropriate to predict sediment toxicity. The integration of results through Sediment Quality Triad approach and principal component analysis allowed observing the effects of natural stressors and dredging on sediment quality and benthic distribution. Even with recent governmental efforts to control, pollution is still relevant in Port of Santos and a threat to local ecosystems. © 2013 Elsevier Ltd.

Influência dos elementos de liga no encruamento proveniente do processo de aplainamento nos aços hadfield

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estanho na Amazônia: o apogeu e o caso da produção

No Brasil, na Região Amazônica, o minério de estanho (cassiterita) é obtido por dragagem em depósitos aluvionares, extração de minério primário e lavra de pequeno porte. O concentrado de estanho obtido (Sn02, contendo 60% de estanho), sendo transformado, via redução, nos fornos elétricos, transformando-o em lingotes de estanho. O metal é primeiramente usado para a produção de folhas de flandres – chapas de aço recobertas com estanho e utilizadas para fabricação de latas para alimentos, bebidas e produtos químicos, bem como na produção de soldas e outras ligas para a indústria em geral (particularmente em segmentos elétricos e eletrônicos). A mina mais importante é a de Pitinga (pureza de 55,3%), localizada a 300 km ao norte de Manaus (AM) e proprietária da Paranapenema. Pitinga dispõe de reservas provadas de columbita-tantalita, criolita e zirconita, contendo terras raras e itrium, cuja viabilidade econômica ainda está sendo estudada. Há inda veios mineralizados no estado de Rondônia, incluindo a mina de Bom Futuro (pureza de 58%), no município de Ariquemes, onde operam os mineradores de pequeno porte. O Brasil é o quinto maior produtor do metal, após Indonésia, China e Peru.