907 resultados para Catchment Runoff
Resumo:
This is the River Taw Salmon Action Plan Final document produced by the Environment Agency in 2000. This final Salmon Action Plan (SAP) for the River Taw catchment has been produced after consideration of feedback from external consultation. The SAP provides a list of the issues and actions which were agreed for a five-year programme to maintain and improve the River Taw salmon stock. Some of these actions have already been delivered before finalising the SAP, but others have yet to be addressed. An attempt has been made to estimate the cost of the actions, identify possible sources of funding and the timescale under which they will be dealt with. The Taw salmon stock is currently failing to meet its spawning target. However, there was a period of compliance in the 1990s following a decade of failure through the 1980s. The freshwater environment of the Taw has improved in recent years. The actions presented in this SAP are perceived as those that are required to address, as far as possible, the important issues and factors currently limiting the salmon stock on the river. This SAP aims to promote long term collaboration between the Agency and other interested parties in managing the River Taw salmon stock and fisheries.
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This is the River Teign Salmon Action Plan Consultation document produced by the Environment Agency in 2003. The report pays attention on the external consultation of the River Teign Salmon Action Plan (SAP). This approach to salmon management within the England and Wales introduces the concept of river-specific Conservation Limits as a method of assessing the status of the salmon stock. The River Teign Salmon Action Plan follows the format of those completed for the Rivers Torridge, Taw and Dart. It is the fourth of eight action plans that will be produced for salmon rivers within the Devon Area Fisheries, Recreation and Biodiversity Team. The River Teign SAP contains a description of the river catchment and highlights particular features that are relevant to the salmon population and the associated fishery. The Teign salmon stock is currently failing to meet its conservation limit. This failure is largely attributed to the reduction in the survival rate during the marine phase of the salmon life cycle. This is likely to constrain stocks to lower levels than have existed historically. Still further catch controls may contribute to a reduction in exploitation rates and allow stocks to recover to meet their conservation limit. Other important actions include the continuation of habitat improvement works which aim to maximise spawning habitat utilisation, spawning success, and juvenile survival and production.
Resumo:
This is the River Teign Salmon Action Plan Final document produced by the Environment Agency in 2003. This final Salmon Action Plan (SAP) for the River Teign catchment has been produced after consideration of feedback from external consultation. This final plan provides a list of the agreed issues and actions for the next five years to maintain and improve the River Teign salmon stock. An attempt has been made to cost these actions, identify possible sources of funding, partners and the timescale under which they will be dealt with. It indicates how the plan will be managed, i.e., implemented and reviewed, and, summarises progress of on-going actions. The low marine survival (likely to be below 10%) is possibly the main cause for the River Teign salmon stock non-compliance with its conservation limit. Actions protecting smolts and maximising spawning activity of returning adults are seen as priorities to contribute to offset the low marine survival. This SAP aims also to promote long term collaboration between the Agency and other interested parties in managing the River Teign salmon stock and fisheries.
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This is the River Torridge Salmon Action Plan Final document produced by the Environment Agency in 2000. This final Salmon Action Plan (SAP) for the River Torridge catchment has been produced after consideration of feedback from external consultation. The SAP provides a list of the issues and actions which were agreed for a five-year programme to maintain and improve the River Torridge salmon stock. Some of these actions have already been delivered before finalising the SAP, but others have yet to be addressed. An attempt has been made to estimate the cost of the actions, identify possible sources of funding and the timescale under which they will be dealt with. The Torridge salmon stock has declined dramatically since the 1960s and is currently failing to meet the spawning target. The decline in the spring fish component has accounted largely for the overall decrease in stocks. The reasons for the decline are not fully understood, but the spring fish problem is recognised as a national issue. The rate of survival over the marine phase has reduced in recent years for both the grilse and multi-sea winter (MSW) components. This is undoubtedly a contributory factor, which may now constrain stocks to lower levels than have existed historically. Agricultural pollution is recognised as one of the main factors limiting freshwater production. This SAP aims to promote long term collaboration between the Agency and other interested parties in managing the River Torridge salmon stock and fisheries.
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This is the final presentation from the Moston Brook Evidence and Measures project which ran from September 2012 to March 2013. Moston Brook water body is part of the River Irwell Pilot Catchment and the objective of the project was to devise reliable measures (actions) which were based on existing evidence and that could be implemented in years 2 and 3 by the Environment Agency and its partner to help meet Water Framework Directive (WDF) requirements and community aspirations. The presentation summarises the main suspected causes of WDF failure, the evidence for this, the main causes for failure in the sub-catchments resulting from the evidence found, and identifies measures to carry out, which will address the WDF failures and improve the quality of the water. This presentation can be used to inform others on how to improve the water quality of Moston Brook, and also to support other similar initiatives.
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A perda de vegetação natural e o aumento das superfícies impermeáveis decorrentes da expansão urbana têm mostrado que os tradicionais sistemas de drenagem urbana são insuficientes e pouco adaptáveis às alterações de uso do solo. Uma das consequências disso é o aumento da velocidade do escoamento superficial (runoff) que favorece as inundações, com enormes prejuízos materiais e ambientais. As inundações ocorrem geralmente quando ha ocorrência de chuvas de alta intensidade. O objetivo deste trabalho foi estudar a contribuição dos telhados verdes modulares submetidos a chuvas de alta intensidade, 155mm/h com duração de 7,0 minutos para retenção e retardo do escoamento superficial. Além disso, foram determinados valores para parâmetros de modelos clássicos chuva-vazão: Método Racional (C) e CN (SCS), que poderá, futuramente, servir de modelagem hidrológica dos impactos da adoção de telhados verdes no controle das enchentes urbanas. A metodologia adotada foi de natureza experimental e envolveu a construção de bancadas com inclinação regulável para suporte dos módulos experimentais e um sistema para indução de chuvas com intensidade controlada. Foram estudados três modelos de sistema modular para telhado verde que permitem o armazenamento de água no fundo da bandeja que compõe os módulos, sendo 2 de 17,0 L (M-17 e F-17) e 1 de 4,0 L (M-4), nas condições de solo seco e solo úmido. Em cada módulo vegetado foram utilizadas 3 espécies de vegetação: Portulaca oleracea (Onze horas), Callisia repens (Dinheiro em penca) e Apnia cordfolia (Rosinha do sol). Os resultados demonstraram que os volumes retidos, calculados a partir da observação do runoff, nas diferentes situações, foram coerentes entre si e com dados relatados na literatura. Os módulos vegetados produziram os melhores resultados com solo seco e os piores resultados com solo úmido. O percentual médio de retenção, considerando todos os tipos de módulos, foi de 58% do volume total de água induzida, com retardo médio de 12 minutos no runoff. Os valores médios de C (Método Racional) foram 0,4, 0,48, 0,36, para os módulos M-17, M-4 e F-17, respectivamente e os de CN (SCS) foram 93, 95, 93, para os mesmos módulos. Conforme esperado, os maiores valores de CN foram para solos úmidos, mantendo a relação que quanto menor o volume retido, maior o runoff e o CN. O módulo F-17 foi o que apresentou melhor desempenho em todos os aspectos (redução do escoamento, retenção hídrica e retardo do runoff). Este estudo demonstra a boa contribuição que esse tipo de sistema pode proporcionar na retenção e retardo do escoamento superficial, mesmo para chuvas intensas de curta duração, principalmente após período de curta estiagem, situação comum em locais de clima tropical. Futuros estudos deverão avaliar o desempenho dos sistemas modulares de telhados verdes com outras características e intensidades de chuvas. A adoção de telhados verdes deve ser cautelosa, sobretudo pela carga extra que esse tipo de sistema representa.
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After an unusually strong and persistent pattern of atmospheric circulation over the United State[s] in Fall 1985, it became quite changeable (although high amplitude anomalies still prevailed). Following a fall that was cold in the West and warm in the East with heavy precipitation, a high pressure ridge set in over the West during December, with generally light precipitation over most of the country. Throughout the winter, the central North Pacific was very active, with large negative atmospheric pressure anomalies centered at about 45°N, l60°W. This activity may have been encouraged by an enhanced meridional eastern North Pacific sea surface temperature (SST) gradient, with positive SST anomalies in the subtropics and negative anomalies in midlatitudes. However, in January, the western high pressure ridge remained strong and temperatures were remarkably warm, increasing the threat of drought in California after the two previous dry winters. However, in February, storms from a greatly expanded and southerly displaced Aleutian Low broke into the West Coast. An unusual siege from February 11 to February 20 flooded central and northern California, with very heavy precipitation and record to near-record runoff. Upwards of 50 percent of annual average precipitation fell on locations from the upper San Joaquin to the Feather River drainage basins, and the largest flow since observations began in the early 1900's was recorded on the Sacramento River at Sacramento. The atmospheric pattern that was responsible for this remarkable stormy spell developed when the western high pressure retrograded to the northwest into the Aleutians, accompanied by the strengthened and southerly extended storm tract that moved into California. Although exact details vary from case to case, this episode displayed meteorological conditions similar to those in several other historical California winter flood events. These included a long duration of very strong westerly to southwesterly winds over a long subtropical fetch into California. Much of the precipitation during this series of storms was orographically induced by the moisture laden flow rising over the Sierra ranges. Due to the warm air mass, snow levels were relatively high (about 7500 feet) during the heaviest precipitation, resulting in copious runoff.
Resumo:
EXTRACT (SEE PDF FOR FULL ABSTRACT): There were many similarities between the February 1986 storm and that of December 1964 and also December 1955. The 1964 storm hit hardest a little further north and the North Coast took the brunt of that storm. December 1955 also produced higher north coastal area runoff. December 1955 produced greater peaks in the central part of the state than the 1964 flood and is perhaps more comparable south of the Lake Tahoe-American River area. But the real surprise this time was the volume. Four reservoirs, Folsom, Black Butte, Pardee, and Comanche, were filled completely and became surcharged (storing more water than the designed capacity). The 10 day total rainfall amounted to half the normal annual totals at many precipitation stations. The February 1986 flood is a vivid reminder of the extremes of California climate and the value of the extensive system of flood control works in the state. Before the storm, especially in January, there was much concern about the dryness of the water year. Then with the deluge, California's flood control systems were tested. By and large the system worked preventing untold damage and misery for most dwellers in the flat lands.
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EXTRACT (SEE PDF FOR FULL ABSTRACT): It seems that an average water year is a rare beast; 1987 was no exception. It turned out to be the ninth driest this century in Northern California's Sacramento River basin. I'd like to summarize for you some interesting facts about water year 1987 and how it affected rainfall, snowpack, runoff, and water storage in California.
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Linear regression models are constructed to predict seasonal runoff by fitting streamflow to temperature, precipitation, and snow water content across a range of elevations. The models are quite successful in capturing the differences in discharge between different elevation watersheds and their interannual variations. This exercise thus provides insight into seasonal changes in streamflow at different elevation watersheds that might occur under a changed climate.
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Marine mammals, such as dolphins, can serve as key indicator species in coastal areas by reflecting the effects of natural and anthropogenic stressors. As such they are often considered sentinels of environmental and ecosystem health (Bossart 2006; Wells et al. 2004; Fair and Becker 2000). The bottlenose dolphin is an apex predator and a key component of many estuarine environments in the southeastern United States (Woodward-Clyde Consultants 1994; SCDNR 2005). Health assessments of dolphins are especially critical in areas where populations are depleted, show signs of epidemic disease and/or high mortality and/or where habitat is being altered or impacted by human activities. Recent assessments of environmental conditions in the Indian River Lagoon, Florida (IRL) and the estuarine waters surrounding Charleston, South Carolina (CHS) highlight the need for studies of the health of local bottlenose dolphins. While the condition of southeastern estuaries was rated as fair in the National Coastal Condition Report (U.S. EPA 2001), it was noted that the IRL was characterized by poorer than expected benthic communities, significant sediment toxicity and increased nutrient concentrations. Similarly, portions of the CHS estuary have sediment concentrations of aliphatic aromatic hydrocarbons, select inorganic metals, and some persistent pesticides far in excess of reported bioeffect levels (Hyland et al. 1998). Long-term trends in water quality monitoring and recent scientific research suggest that waste load assimilation, non-point source runoff impacts, contaminated sediments, and toxic pollutants are key issues in the CHS estuary system. Several ‘hot spots’ with high levels of heavy metals and organic compounds have been identified (Van Dolah et al. 2004). High concentrations of anthropogenic trace metals, polychlorinated biphenyls (PCB’s) and pesticides have been found in the sediments of Charleston Harbor, as well as the Ashley and Cooper Rivers (Long et al. 1998). Two superfund sites are located within the CHS estuary and the key contaminants of concern associated with these sites are: polycyclic aromatic hydrocarbons (PAH), lead, chromium, copper, arsenic, zinc and dioxin. Concerns related to the overall health of IRL dolphins and dermatologic disease observed in many dolphins in the area (Bossart et al. 2003) initiated an investigation of potential factors which may have impacted dolphin health. From May-August 2001, 35 bottlenose dolphins died in the IRL during an unusual mortality event (MMC 2003). Many of these dolphins were diagnosed with a variety of skin lesions including proliferative ulcerative dermatitis due to protozoa and fungi, dolphin pox and a vesicular dermatopathy of unknown etiology (Bossart et al. 2003). Multiple species from fish to dolphins in the IRL system have exhibited skin lesions of various known and unknown etiologies (Kane et al. 2000; Bossart et al. 2003; Reif et al. 2006). On-going photo-identification (photo-ID) studies have documented skin diseases in IRL dolphins (Mazzoil et al. 2005). In addition, up to 70% of green sea turtles in the IRL exhibit fibropapillomas, with the highest rates of occurrence being seen in turtles from the southern IRL (Hirama 2001).
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Estuaries provide critical nursery habitat for many commercially and recreationally important fish and shellfish species. These productive, diverse ecosystems are particularly vulnerable to pollution because they serve as repositories for non–point-source contaminants from upland sources, such as pesticide runoff. Atrazine, among the most widely used pesticides in the United States, has also been one of the most extensively studied. There has not, however, been a specific assessment of atrazine in marine and estuarine ecosystems. This document characterizes the presence and transformation of atrazine in coastal waters, and the effects of atrazine on marine organisms. Review of marine and estuarine monitoring data indicate that atrazine is chronically present in U.S. coastal waters at relatively low concentrations. The concentrations detected have typically been below acute biological effects levels, and below the U.S. EPA proposed water quality criteria for atrazine. While direct risk of atrazine impacts are low, uncertainty remains regarding the effects of long-term low levels of atrazine in mixture with other contaminants. It is recommended that best management practices, such as the use of vegetative buffers and public education about pesticide use, be encouraged in the coastal zone to minimize runoff of atrazine into marine and estuarine waters.
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High salinity estuaries in the southeastern U.S. have experienced increased inputs of contaminants from nonpoint source (NPS) urban runoff and decreases in habitat due to filling of wetlands and dock/bulkhead construction. Urbanization may pose significant risks to estuarine fauna, particularly crustaceans. The grass shrimp of the genus Palaemonetes, is one of the dominant species found in estuarine tidal creeks, accounting for greater than 50% of all macropelagic fauna on an annual basis. Spatial analytical and geographic information system techniques were used to determine which factors influenced the Palaemonetes population structures in a South Carolina bar-built estuary surrounded by urban development. Impacts from land use practices were investigated using concentric circular buffers around study sites. Factors investigated included sediment-associated polycyclic aromatic hydrocarbons concentration, land use classification, percent impervious surfaces, and other selected urban factors. Geographic information system and statistical modeling showed quantitative relationships between land use class and impacts on Palaemonetes density. The study suggests that habitat loss is a major factor influencing grass shrimp densities. Multiple regression modeling suggests a significant relationship between habitat alterations and Palaemonetes densities.
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Over the past one hundred and fifty years, the landscape and ecosystems of the Pacific Northwest coastal region, already subject to many variable natural forces, have been profoundly affected by human activities. In virtually every coastal watershed from the Strait of Juan de Fuca to Cape Mendocino, settlement, exploitation and development of resou?-ces have altered natural ecosystems. Vast, complex forests that once covered the region have been largely replaced by tree plantations or converted to non-forest conditions. Narrow coastal valleys, once filled with wetlands and braided streams that tempered storm runoff and provided salmon habitat, were drained, filled, or have otherwise been altered to create land for agriculture and other uses. Tideflats and saltmarshes in both large and small estuaries were filled for industrial, commercial, and other urban uses. Many estuaries, including that of the Columbia River, have been channeled, deepened, and jettied to provide for safe, reliable navigation. The prodigious rainfall in the region, once buffered by dense vegetation and complex river and stream habitat, now surges down sirfiplified stream channels laden with increased burdens of sediment and debris. Although these and many other changes have occurred incrementally over time and in widely separated areas, their sum can now be seen to have significantly affected the natural productivity of the region and, as a consequence, changed the economic structure of its human communities. This activity has taken place in a region already shaped by many interacting and dynamic natural forces. Large-scale ocean circulation patterns, which vary over long time periods, determine the strength and location of currents along the coast, and thus affect conditions in the nearshore ocean and estuaries throughout the region. Periodic seasonal differences in the weather and ocean act on shorter time scales; winters are typically wet with storms from the southwest while summers tend to be dry with winds from the northwest. Some phenomena are episodic, such as El Nifio events, which alter weather, marine habitats, and the distribution and survival of marine organisms. Other oceanic and atmospheric changes operate more slowly; over time scales of decades, centuries, and longer. Episodic geologic events also punctuate the region, such as volcanic eruptions that discharge widespread blankets of ash, frequent minor earthquakes, and major subduction zone earthquakes each 300 to 500 years that release accumulated tectonic strain, dropping stretches of ocean shoreline, inundating estuaries and coastal valleys, and triggering landslides that reshape stream profiles. While these many natural processes have altered, sometimes dramatically, the Pacific Northwest coastal region, these same processes have formed productive marine and coastal ecosystems, and many of the species in these systems have adapted to the variable environmental conditions of the region to ensure their long-term survival.
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A significant fraction of the total nitrogen entering coastal and estuarine ecosystems along the eastern U.S. coast arises from atmospheric deposition; however, the exact role of atmospherically derived nitrogen in the decline of the health of coastal, estuarine, and inland waters is still uncertain. From the perspective of coastal ecosystem eutrophication, nitrogen compounds from the air, along with nitrogen from sewage, industrial effluent, and fertilizers, become a source of nutrients to the receiving ecosystem. Eutrophication, however, is only one of the detrimental impacts of the emission of nitrogen containing compounds to the atmosphere. Other adverse effects include the production of tropospheric ozone, acid deposition, and decreased visibility (photochemical smog). Assessments of the coastal eutrophication problem indicate that the atmospheric deposition loading is most important in the region extending from Albemarle/Parnlico Sounds to the Gulf of Maine; however, these assessments are based on model outputs supported by a meager amount of actual data. The data shortage is severe. The National Research Council specifically mentions the atmospheric role in its recent publication for the Committee on Environmental and Natural Resources, Priorities for Coastal Ecosystem Science (1994). It states that, "Problems associated with changes in the quantity and quality of inputs to coastal environments from runoff and atmospheric deposition are particularly important [to coastal ecosystem integrity]. These include nutrient loading from agriculture and fossil fuel combustion, habitat losses from eutrophication, widespread contamination by toxic materials, changes in riverborne sediment, and alteration of coastal hydrodynamics. "