Study on Water Resources Regulation and Reservoir Operating Prediction for Suppression of Salt Water Intrusion in the Pearl River Estuary

Salt water intrusion occurred frequently during dry season in Modaomen waterway of the Pearl River Estuary. With the development of region's economy and urbanization, the salt tides affect the region's water supply more and more seriously in recent years. Regulation and allocation of freshwater resources of the upper rivers of the estuary to suppress the salt tides is becoming important measures for ensuring the water supply security of the region in dry season. The observation data analysis showed that the flow value at the Wuzhou hydrometric station on the upper Xijiang river had a good correlation with the salinity in Modaomen estuary. Thus the flow rate of Wuzhou has been used as a control variable for suppression of salt tides in Modaomen estuary. However, the runoff at Wuzhou mainly comes from the discharge of Longtan reservoir on the upper reaches of Xijiang river and the runoff in the interval open valley between Longtan and Wuzhou sections. As the long distance and many tributaries as well as the large non-controlled watershed between this two sections, the reservoir water scheduling has a need for reasonable considering of interaction between the reservoir regulating discharge and the runoff process of the interval open watershed while the deployment of suppression flow at Wuzhou requires longer lasting time and high precision for the salt tide cycles. For this purpose, this study established a runoff model for Longtan - Wuzhou interval drainage area and by model calculations and observation data analysis, helped to understand the response patterns of the flow rate at Wuzhou to the water discharge of Longtan under the interval water basin runoff participating conditions. On this basis, further discussions were taken on prediction methods of Longtan reservoir discharge scheduling scheme for saline intrusion suppression and provided scientific and typical implementation programs for effective suppression flow process at the Wuzhou section.

Modelling of saline intrusion in marine outfalls

Since their introduction in the 1950s, marine outfalls with diffusers have been prone to saline intrusion, a process in which seawater ingresses into the outfall. This can greatly reduce the dilution and subsequent dispersion of wastewater discharged, sometimes resulting in serious deterioration of coastal water quality. Although long aware of the difficulties posed by saline intrusion, engineers still lack satisfactory methods for its prediction and robust design methods for its alleviation. However, with recent developments in numerical methods and computer power, it has been suggested that commercially available computational fluid dynamics (CFD) software may be a useful aid in combating this phenomenon by improving understanding through synthesising likely behaviour. This document reviews current knowledge on saline intrusion and its implications and then outlines a model-scale investigation of the process undertaken at Queen's University Belfast, using both physical and CFD methods. Results are presented for a simple outfall configuration, incorporating several outlets. The features observed agree with general observations from full-scale marine outfalls, and quantify the intricate internal flow mechanisms associated with saline intrusion. The two-dimensional numerical model was found to represent saline intrusion, but in a qualitative manner, not yet adequate for design purposes. Specific areas requiring further development were identified. The ultimate aim is to provide a reliable, practical and cost effective means by which engineers can minimise saline intrusion through optimised outfall design.

Contribution à l'étude des modifications hydro-sédimentaires consécutives à la réouverture artificielle de l'embouchure du Comoé à Grand-Bassam

The Bassam artificial inlet was opened (in September 22, 1987) in order to revacuate offshore invasive aquatic plants. This has considerably modified the hydro-sedimentary environment of the lagoonal domain at Grand-Bassam. Tidal currents effect has confered the lagoonal waters an estuarine feature, the saline intrusion (25-35%o) increased beyond the Moossou bridges up to the confluence of the Comoe river. This has led to a cleaning of the river lower course and above all to the bottoms of the lagoon, which were previously confined. The remobilization of mud (from lagoonal bottoms around Bouet Island) evacuated offshore, has exposed lagoonal and oceanic sandy features. This new system remains fragile, with the seasonal (low river-flow) clogging.

A report on the strategic fisheries stock assessment survey of the River Winster 1995 together with a coarse fish survey in 1994 and reference to the 1995 drought

This is the report on the strategic fisheries stock assessment survey of the River Winster 1995 together with a coarse fish survey in 1994 and reference to the 1995 drought, produced by the Environment Agency North West in 1996. Salmonid production within the Winster catchment was dominated by trout although good densities of salmon juveniles were found on some main river sites. Despite suffering drought conditions for much of 1995, only salmon fry production appeared to have been affected. Coarse fish populations once found in the lower reaches of the Winster appear to have declined to very low levels with no fish sampled. This may be partly due to broken tidal gates allowing saline intrusion. It seems that the lower river was suited to the development of a recreational coarse fishery, now that the gates have been repaired. This report completes the strategic stock assessment surveys planned for the period 1992-1995. It represents the last major catchment that was surveyed to determine the current status of fisheries in the South and South West Cumbria areas.

Water quality impacts and palaeohydrogeology in the East Yorkshire Chalk Aquifer, UK

A large hydrochemical data-set for the East Yorkshire Chalk has been assessed. Controls on the distribution of water qualities within this aquifer reflect: water-rock interactions (affecting especially the carbonate system and associated geochemistry); effects of land-use change (especially where the aquifer is unconfined); saline intrusion and aquifer refreshening (including ion exchange effects); and aquifer overexploitation (in the semi-confined and confined zones of the aquifer). Both Sr and I prove useful indicators of groundwater ages, with I/Cl ratios characterising two sources of saline waters. The hydrochemical evidence clearly reveals the importance of both recent management decisions and palaeohydrogeology in determining the evolution and distribution of groundwater salinity within the artesian and confined zones of the aquifer. Waters currently encountered in the aquifer are identified as complex (and potentially dynamic) mixtures between modern recharge waters, modern seawater, and old seawaters which entered the aquifer many millennia ago.

Hidroquímica e qualidade das águas subterrâneas da Ilha de Santiago - Cabo Verde

A ilha de Santiago, Cabo Verde é uma ilha de origem vulcânica, constituída basicamente por lavas e piroclastos, localizada no Oceano Atlântico ao lado da costa ocidental de África. A ilha é caracterizada por três unidades hidrogeológicas, sendo estas a Formação de Base (semi-confinada), a Formação Intermédia (freática) e a Formação Recente (freática), que apresentam características geológicas e comportamentos hidráulicos que as diferenciam, recebendo recarga directa e/ ou diferida por infiltração das águas de chuva e descarregam ao mar, na rede hidrográfica ou, ainda, em outros níveis aquíferos subjacentes, desde que induzidos por gradientes hidráulicos favoráveis. O clima de Santiago é árido a semi-árido, com precipitações muito escassas e irregulares, condicionadas na sua distribuição pela altitude, ventos e orientação das vertentes, dando por vezes origem a períodos de seca prolongados. Em anos de ‘boa’ chuva, as precipitações propiciam a existência temporária de recursos hídricos superficiais e a recarga dos recursos de água subterrânea. Foi realizado um estudo hidrogeoquímico detalhado da ilha que incluiu a recolha de amostras em 133 pontos de água, entre furos, poços e nascentes. A composição química das águas analisadas na ilha de Santiago apresenta significativas variações em função da geologia e do tempo de residência. Na ausência de episódios de contaminação, as águas subterrâneas têm uma composição do tipo bicarbonatada-sódica (HCO3-Na) nas zonas mais altas da ilha, onde afloram as formações da Unidade Aquífera Intermédia. Nas zonas mais próximas da costa ocorrem águas de composição cloretada-magnesiana (Cl-Mg) ou cloretada-sódica (Cl-Na). Estas últimas predominam nas partes terminais das ribeiras, onde afloram materiais de elevada permeabilidade, e o excesso de bombagem para irrigação tem conduzido a um avanço da cunha de intrusão marinha. A ocorrência da fácies Cl-Na é neste caso o resultado de processos de intercâmbio catiónico que ocorrem durante o processo de intrusão e é concordante com os elevados teores de cloretos e de condutividade eléctrica observados. Os resultados das análises de isótopos estáveis de oxigénio-18 e deutério, realizadas em amostras recolhidas a distintas altitudes, revelam um gradiente negativo com a altitude, que já tinha sido verificado em outras ilhas com declives acentuados, permitindo assim determinar altitudes de recarga de água subterrânea. Os estudos hidrogeoquímicos até agora realizados permitiram caracterizar os principais níveis aquíferos da ilha de Santiago, colocando em evidência a limitada recarga do aquífero e o risco de gradual degradação dos recursos de água subterrânea por fenómenos de intrusão salina e contaminação agrícola. Estes resultados revelam a importância da gestão integrada da qualidade e quantidade dos parcos recursos de água subterrânea na ilha de Santiago.

Ecological interactions in populations facing environmental stress

O zooplâncton, particularmente os cladóceros, são organismos de água doce importantes na regulação da produção primária dos ecossistemas de água doce. No entanto, também podem adaptar-se a condições salobras. Tendo em conta as previsões no âmbito das alterações climáticas, a intrusão salina pode ocorrer a par com a subida de temperatura. As populações de água doce podem ficar vulneráveis aos efeitos interativos da salinidade e da temperatura, de acordo com os seus limites de tolerância e capacidade de adaptação ao stress ambiental. Assim, a presente tese analisou as interações resultantes das alterações destes agentes de stress em populações de cladóceros de água doce. Primeiro, comparou-se a halotolerância de diferentes genótipos de Simocephalus vetulus provenientes de populações de água doce e de água salobra de modo a avaliar a existência de uma componente genética de resistência à salinidade. A sensibilidade aguda dos genótipos variou na mesma gama de concentrações; todavia, todos os genótipos da população salobra, exceto um, foram mais tolerantes do que os de água doce, em termos de tempo à imobilização. Contudo, não foi possível estabelecer uma relação entre a performance reprodutiva em condições salobras e o contexto ambiental de origem destes genótipos. Mais, estes ensaios mostraram que as populações de água doce têm potencial para tolerar incrementos de salinidade. Como tal, pode-se concluir que a seleção a que os genótipos estão sujeitos no seu local de origem foi mais fraca do que o esperado. Segundo, investigou-se a capacidade de aclimatação de Daphnia galeata à salinidade e temperatura, de modo a avaliar a halotolerância de Daphnia a duas temperaturas num cenário de aclimatação multigeracional. O objetivo foi compreender se a pré-adaptação ao stress ambiental (20ºC e 25ºC versus 0 g/L e 1 g/L de NaCl) influenciou posteriormente as respostas a estes agentes de stress. Verificou-se uma tendência para um aumento de sensibilidade ao NaCl, a temperaturas mais elevadas. No entanto, este efeito foi anulado após nove gerações, mas apenas quando os organismos foram aclimatados aos dois agentes de stress em simultâneo (salinidade e temperatura elevada). Terceiro, demonstrou-se experimentalmente que a salinidade interferiu com a competição interespecífica, alterando a composição das comunidades zooplanctónicas. Este conjunto de evidências permitiu-nos refletir nos múltiplos impactos de agentes de stress, particularmente os relacionados com as previsões de alterações climáticas. Em paralelo aos estudos de natureza experimental, e numa perspetiva de Educação para o Desenvolvimento Sustentável (EDS), importa também promover o desenvolvimento de competências necessárias à compreensão de mudanças ambientais globais (e.g., o impacto da salinidade e da temperatura) para implementar estratégias de mitigação e adaptação. Neste contexto, foi realizada uma atividade com estudantes do ensino secundário, que se tornou uma boa oportunidade para a sua aprendizagem e aquisição de competências de interpretação de dados experimentais, assim como de sensibilização para as questões ambientais.

Effetti della Salinizzazione sugli Invertebrati del suolo

Lo scopo di questa tesi è quello di valutare l'effetto della salinizzazione dei suoli sugli invertebrati edafici. Nell'ambito di questo obiettivo generale sono state effettuate due distinte attività di ricerca: una indagine sul campo e una serie di esperimenti di laboratorio. Lo studio sul campo è stato condotto nella Pineta di San Vitale (Ravenna, Italia). L'obiettivo specifico è stato quello di valutare la qualità biologica dei suoli attraverso l'analisi del popolamento dei microartropodi edafici, in relazione alla diversità del suolo e in particolare alla salinizzazione. La qualità biologica dei suoli è stata valutata mediante l'indice QBS-ar. La Pineta è stata campionata nella zona Est, più colpita da intrusione salina e nella zona Ovest dove questo fenomeno è meno evidente. I campionamenti sono stati effettuati in primavera ed estate. I risultati confermano che le caratteristiche chimico-fisiche si modificano in base al gradiente sommità dunali-depressioni interdunali. Per quanto riguarda il popolamento dei microartropodi alcune caratteristiche sono comuni alla maggior parte delle stazioni con lo stesso pedotipo. Non è stato evidenziato alcuno stress sui popolamenti attribuibule alla salinizzazione. Nel complesso, i valori di QBS-ar sono piuttosto elevati. Gli esperimenti di laboratorio sono stati finalizzata alla valutazione degli effetti combinati della salinità del suolo e della contaminazione da pesticidi (chlorpyrifos) sul lombrico Eisenia andrei. Nel complesso, i risultati indicano che effetti avversi sui lombrichi sono possibili a livelli di salinizzazione dei suoli ancora compatibili a concentrazioni di chlorpyrifos che sono piuttosto alte in confronto con i tipici risultati di campo, ma ancora compatibili con l'uso consigliato.

Isotope Study of Moisture Sources, Recharge Areas and Groundwater Flowpaths within the Eastern Batinah Coastal Plain, Sultanate of Oman

Oxygen and hydrogen isotope analyses of rainfall samples collected on the eastern Batinah coastal plain of northern Oman between 1995 and 1998 indicate two different principal water vapor sources for precipitation in the area: a northern, Mediterranean source and a southern, Indian Ocean source. As a result, two new local meteoric water lines were defined for the study area. Isotopic analyses of groundwater samples from over 200 springs and wells indicate that the main source of water to the Batinah coastal alluvial aquifer is high-altitude rainfall from the adjacent Jabal Akhdar Mountains, originating from a combination of northern and southern moisture sources. The groundwater recharged at high-altitude forms two plumes of water which is depleted in the heavy isotopes 18O and 2H and stretches from the mountains across the coastal plain to the sea, thereby retaining a chemical homogeneity horizontally and vertically down to a depth exceeding 300 m. In contrast, in areas adjacent to these two plumes the alluvial aquifer is geochemically stratified. Near the coast, saline intrusion results in abrupt changes in chloride concentrations and isotope values.

Changing use and hydromorphological adjustment in a coastal lagoon–estuarine system, the Ria de Aveiro, Portugal

Today the Ria de Aveiro of northern Portugal has a hydromorphological regime in which river influence is limited to periods of flood. For most of the annual cycle, tidal currents and wind waves are the major forcing agents in this complex coastal lagoon–estuarine system. The system has evolved over two centuries from one that was naturally fluvially dominant to one that is today tidally dominant. Human influence was a trigger for these changes, starting in 1808 when its natural evolution was halted by the construction of a new inlet/outlet channel through the mobile sand spit that isolates it from the Atlantic Ocean. In consequence, tidal ranges in the lagoon increased rapidly from ~0.1 m to >1 m and continued to increase, as a result of continued engineering works and dredging, today reaching ~3 m on spring tides. Hydromorphological adjustments that have taken place include the deepening of channels, an increase in the area of inter-tidal flats, regression of salt marsh, increased tidal propagation and increased saline intrusion. Loss of once abundant submerged aquatic vegetation (SAV), due to increased tidal flows, exacerbated by increased recreational activities, has been accompanied by a change from fine cohesive sediments to coarser, mobile sediments with reduced biological activity.

Saline water intrusion from deep artesian sources in McGregor Isles area of Lee County, Florida

Upward leakage of saline water from an artesian aquifer below 1,500 feet has caused an increase in chloride concentration in the lower Hawthorn aquifer from less than 1,000 mg/1 (milligrams per liter) to values ranging from about 1,300 to 15,000 mg/1. Similarly the higher temperatures of the intruding water has caused an increase in water temperatures in the aquifer from 82"F to values ranging from 83 to 93"F. The intruding water moves upward either through the open bore hole of deep wells or test holes, or along a fault or fracture system, which has been identified in the area. From these points of entry into the lower Hawthorn aquifer, the saline water spreads laterally toward the south and southeast, but is generally confined to components of the fault system. The saline water moves upward from the lower Hawthorn aquifer into the upper Hawthorn aquifer through the open bore hole of wells, which connect the aquifers. This movement has resulted in an increase in chloride from less than 200 mg/1 in the unaffected parts of the upper Hawthorn aquifer to values commonly ranging from about 300 to more than 3,000 mg/1 in parts of the aquifer affected by upward leakage. The upper Hawthorn aquifer is the principal source of ground-water supply for public water-supply systems in western Lee County. Similar effects have been noted in the water-table aquifer, where chloride increased from less than 100 to concentrations ranging from about 500 to more than 5,000 mg/1. This was caused by the downward infiltration of water discharged at land surface from wells tapping the lower Hawthorn aquifer. The spread of saline water throughout most of the McGregor Isles area is continuing as of 1971. (40 page document)

Salinity Intrusion and Seasonal Water Quality Variations in the Tidal Canals of Cochin

The study conducted on the salinity intrusion and seasonal water quality variations in the tidal canals of cochin. The main objectives are, salinity intrusion profile, water quality variation of the surface water of the canals,hierarchical utility of the water bodies and to understand the non-conservative components in the water body. The parameters monitored werepH,temperature,alkalinity,conductivity,DO(dissolvedoxygen),COD(chemical oxygen demand),BOD(biochemical oxygen demand0,chloride, total hardness, calcium hardness, dissolved phosphate, nitrate, total iron, sulphate, turbidity, total coliform and SUVA at 254nm. The tidal canals of GCDA were found to be creeks extending to the interior, canals inter connecting parts of the estuary or canals with seasonally broken segments. Based on utility the canals could be classified as: canals heavely polluted and very saline,canals polluted by urban waste , canals having fresh water for most part of the year and not much polluted, fresh water bodies heavily polluted. During the rainy months carbon fixation by plankton is nonexistent,and during the dry months Chitrapuzha becomes a sink of phosphate. The study indicated abiotic subrouts for dissolved phosphate and revealed the potential pitfalls in LOICZ modeling exercise on sewage ladentidal canals. It was also found that all canals except for the canals of West cochin and chittoorpuzha have fresh water for some part of the year. The water quality index in the durable fresh water stretches was found to be of below average category.

Subchronic effects of fluoxetine on conditioned suppression produced by a hot air blast

Conditioned suppression is an animal model of anxiety disorders that has been broadly used to investigate the behavioral effects of different drugs. However, various methodological variables (e.g., the type of aversive stimulus) that supposedly interfere with the acquisition of conditioned suppression may also contribute to conflicting results among the studied drugs. Additionally, few studies have sought to investigate the effects of selective serotonin reuptake inhibitors (SSRIs). The present study investigated the effect of subchronic 5-day administration of 5 mg/kg fluoxetine in the retention of conditioned suppression produced by a hot air blast (HAB). The subjects were 12 albino Wistar rats distributed into an Experimental Group (EG) and Control Group (CG). After sessions were conducted to pair two stimuli, a sound and HAB, fluoxetine (EG) or saline (CG) was administered. Twentyfour hours after the last injection, a test session was conducted. The results showed no difference between groups. Fluoxetine (5 mg/kg) did not exert anxiolytic effects in this model of conditioned suppression produced by a HAB. Keywords: conditioned suppression; fluoxetine; subchronic; hot air blast.